Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0016887 ATP hydrolysis activity	IBA GO_REF:0000033	ACCEPT	Summary: DnaK has intrinsic ATPase activity that is central to its chaperone cycle. The ATP hydrolysis rate is stimulated by substrates and DnaJ (PMID:7776367). IBA annotation is well-supported phylogenetically across the HSP70 family and experimentally validated for DnaK. Reason: Core enzymatic activity of DnaK. ATP hydrolysis drives the conformational cycle essential for chaperone function. Well-documented experimentally (PMID:7776367, PMID:7937953). Supporting Evidence: PMID:7776367 DnaK ATPase was stimulated by substrates (ninefold) and DnaJ (13-fold) through stimulation of the rate limiting step, gamma-phosphate cleavage PMID:7937953 upon interaction with luciferase-DnaJ, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable luciferase-DnaK-DnaJ complex
GO:0031072 heat shock protein binding	IBA GO_REF:0000033	ACCEPT	Summary: DnaK directly binds its co-chaperones DnaJ (Hsp40) and GrpE, as well as HtpG (Hsp90) and ClpB (Hsp100). The IBA annotation reflects conserved interactions across the HSP70 family. Multiple experimental studies confirm these interactions in E. coli (PMID:9103205, PMID:2522091, PMID:21525416). Reason: DnaK forms functional complexes with multiple heat shock proteins including DnaJ, GrpE, HtpG, and ClpB. This is a well-established feature of the HSP70 chaperone system. Supporting Evidence: PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bound to the ATPase domain of the molecular chaperone DnaK PMID:21525416 Results indicate that E. coli Hsp90 and DnaK interact in vivo and in vitro
GO:0044183 protein folding chaperone	IBA GO_REF:0000033	ACCEPT	Summary: DnaK is the canonical bacterial protein folding chaperone (foldase). It assists protein folding through iterative ATP-driven binding-and-release cycles (PMID:7937953). The IBA annotation is well-supported and represents a core function of the HSP70 family. Reason: Core molecular function of DnaK. The IBA captures the foldase activity at the correct level of specificity. DnaK has both GO:0044183 (general foldase) and GO:0140662 (ATP-dependent foldase) annotations; both are appropriate with GO:0140662 being more specific. Supporting Evidence: PMID:7937953 Several rounds of ATP-dependent interaction with DnaK and DnaJ are required for fully efficient folding
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: DnaK is predominantly a cytosolic protein. This is supported by multiple proteomic studies (PMID:15911532, PMID:18304323) and IBA phylogenetic inference. Reason: Well-established localization for DnaK, confirmed by both IDA and IBA evidence.
GO:0042026 protein refolding	IBA GO_REF:0000033	ACCEPT	Summary: DnaK is directly involved in refolding heat-damaged proteins. Schroder et al. (1993) showed that DnaK, DnaJ, and GrpE are essential for reactivation of heat-inactivated luciferase both in vivo and in vitro (PMID:7900997). Skowyra et al. (1990) demonstrated DnaK reactivates heat-inactivated RNA polymerase in an ATP-dependent manner (PMID:2203539). Reason: Core biological process for DnaK. Protein refolding (repair of heat-damaged proteins) is one of the best-characterized functions of the DnaK/DnaJ/GrpE system. Supporting Evidence: PMID:7900997 DnaK, DnaJ and GrpE did not prevent luciferase inactivation, but were essential for its reactivation PMID:2203539 heat-inactivated and aggregated RNA polymerase is both disaggregated and reactivated following simultaneous incubation with DnaK protein and hydrolyzable ATP
GO:0045892 negative regulation of DNA-templated transcription	IEA GO_REF:0000108	ACCEPT	Summary: This IEA annotation is inferred from GO:0016989 (sigma factor antagonist activity) via logical inference. DnaK binds and inactivates sigma32, which represses heat shock gene transcription (PMID:8599944). The inference is sound since antagonizing sigma32 leads to negative regulation of sigma32-dependent transcription. Reason: Logically sound inference from the experimentally validated sigma factor antagonist activity (GO:0016989). DnaK-mediated sequestration of sigma32 represses heat shock gene transcription. Supporting Evidence: PMID:8599944 DnaK and DnaJ cooperatively inhibit sigma32 activity in heat shock gene transcription
GO:0000166 nucleotide binding	IEA GO_REF:0000043	ACCEPT	Summary: IEA annotation from UniProt keyword mapping. DnaK binds both ATP and ADP, which is well-established experimentally (PMID:7776367, PMID:19439666). This is a broader parent of the more specific ATP binding annotation. Reason: Correct but very general. Subsumed by more specific ATP binding (GO:0005524) and ADP binding (GO:0043531) annotations which are experimentally validated. Acceptable as an IEA annotation.
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for ATP binding, which is also supported by direct IDA evidence (PMID:9103205, PMID:7776367). DnaK has a well-characterized N-terminal ATPase domain. Reason: Correct annotation. ATP binding is a core feature of DnaK's N-terminal nucleotide-binding domain. Redundant with IDA-supported annotations but acceptable.
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: IEA annotation from UniProt subcellular location mapping. DnaK is predominantly cytoplasmic, confirmed by HDA (PMID:16858726) and IDA (PMID:15911532, PMID:18304323) evidence as well. Reason: Correct localization. Broader than cytosol (GO:0005829) but acceptable as IEA.
GO:0005886 plasma membrane	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: IEA annotation from UniProt subcellular location. UniProt lists DnaK as a peripheral inner membrane protein (PMID:16079137). DnaK has also been found associated with membrane fractions (PMID:16858726 HDA). This is a secondary localization. Reason: DnaK is primarily cytosolic but has been detected at the cell inner membrane as a peripheral protein. This is not a core localization but is supported by UniProt annotations citing PMID:16079137.
GO:0006260 DNA replication	IEA GO_REF:0000043	KEEP AS NON CORE	Summary: IEA annotation from UniProt keyword mapping (KW-0235 DNA replication). UniProt describes DnaK as essential for phage lambda DNA replication and involved in chromosomal DNA replication through interaction with DnaA. This reflects a genuine but non-core function. Reason: DnaK's role in DNA replication is well-documented for phage lambda (releasing lambda O and P from the preprimosomal complex) and proposed for chromosomal replication via DnaA interaction. However, this is not DnaK's primary evolved function -- it reflects chaperone activity applied to replication machinery, not a direct replication function.
GO:0006457 protein folding	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro (IPR012725, Chaperone_DnaK). DnaK is a core protein folding chaperone. This BP annotation is correct and also supported by IDA evidence (PMID:9103205). Reason: Protein folding is the core biological process in which DnaK participates. This IEA is consistent with the extensive experimental evidence.
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000002	ACCEPT	Summary: IEA annotation from InterPro (IPR013126, Hsp_70_fam). Duplicates the IBA annotation for the same term. DnaK has well-characterized intrinsic ATPase activity. Reason: Correct. Duplicate of the IBA annotation but from a different evidence source. ATP hydrolysis is central to DnaK function.
GO:0051082 unfolded protein binding	IEA GO_REF:0000002	MODIFY	Summary: IEA annotation from InterPro (IPR012725). GO:0051082 is proposed for obsoletion (go-ontology#30962). DnaK does bind unfolded proteins, but this binding is in the context of its foldase activity, not as a passive binder. The function is better captured by GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent protein folding chaperone), both of which DnaK already has. Reason: GO:0051082 is proposed for obsoletion. DnaK's binding of unfolded proteins is mechanistically part of its ATP-dependent foldase cycle, not passive binding. The correct MF is GO:0044183 or its child GO:0140662. DnaK can also function as a holdase in some contexts (PMID:2203539, ATP-independent protection from aggregation), but the holdase NTR has not yet been created. Proposed replacements: protein folding chaperone Supporting Evidence: PMID:7937953 DnaK, the Hsp70 protein of Escherichia coli, is regulated by the chaperone protein DnaJ and the cofactor GrpE...we have analyzed a model reaction in which DnaK, DnaJ, and GrpE mediate the folding of denatured firefly luciferase
GO:0051087 protein-folding chaperone binding	IEA GO_REF:0000117	ACCEPT	Summary: IEA annotation from ARBA machine learning. DnaK binds multiple chaperones including DnaJ, GrpE, HtpG, and ClpB. This is also supported by IPI evidence (PMID:9103205, PMID:21525416). Reason: Correct. DnaK physically interacts with multiple protein-folding chaperones as part of its functional cycle.
GO:0005515 protein binding	IPI PMID:10521435 Structural features required for the interaction of the Hsp7...	MODIFY	Summary: IPI with DnaJ (P08622). Suh et al. (1999) characterized structural features required for DnaK-DnaJ interaction. This is a functionally meaningful chaperone-co-chaperone interaction central to DnaK function. Reason: The DnaK-DnaJ interaction is a core co-chaperone interaction, not generic protein binding. Better captured by GO:0031072 (heat shock protein binding) or GO:0051087 (protein-folding chaperone binding), which DnaK already has. Proposed replacements: protein-folding chaperone binding
GO:0005515 protein binding	IPI PMID:15690043 Interaction network containing conserved and essential prote...	MARK AS OVER ANNOTATED	Summary: IPI from a large-scale interaction study (Butland et al. 2005) detecting DnaK interactions with multiple E. coli proteins including DnaJ (P08622), GrpE (P09372), RpoH (P0AGB3), and many others. As a chaperone, DnaK is expected to interact with a wide range of cellular proteins. GO:0005515 is uninformative. Reason: Large-scale protein interaction study. DnaK as a chaperone interacts with many cellular proteins; generic protein binding does not capture the mechanistic basis. The specific co-chaperone interactions (DnaJ, GrpE) are better annotated with GO:0051087.
GO:0005515 protein binding	IPI PMID:16139413 Analysis of the Escherichia coli RNA degradosome composition...	MARK AS OVER ANNOTATED	Summary: IPI with Rne/RNase E (P21513). DnaK was found associated with the RNA degradosome complex. This likely reflects a chaperone-substrate interaction rather than a stable functional complex. Reason: DnaK association with the RNA degradosome is likely a chaperone-substrate interaction. Generic protein binding is uninformative for a promiscuous chaperone.
GO:0005515 protein binding	IPI PMID:16606699 Large-scale identification of protein-protein interaction of...	MARK AS OVER ANNOTATED	Summary: IPI from large-scale protein-protein interaction study (Arifuzzaman et al. 2006). DnaK interactions with GrpE, HtpG, RpoH, CbpA and others detected. Reason: Large-scale interaction screen. DnaK is a chaperone with many interactors. GO:0005515 is uninformative. Specific functionally meaningful interactions are already captured by more specific terms.
GO:0005515 protein binding	IPI PMID:16858726 A complexomic study of Escherichia coli using two-dimensiona...	MARK AS OVER ANNOTATED	Summary: IPI from complexomic study (Maddalo et al. 2006) detecting DnaK interactions with GrpE (P09372) and ClpB (P63284) by 2D blue native/SDS-PAGE. Reason: DnaK-GrpE and DnaK-ClpB interactions are well-known chaperone system interactions, better described by GO:0031072 or GO:0051087 than generic protein binding.
GO:0005515 protein binding	IPI PMID:17357109 70-kDa heat shock proteins: specific interactions with HLA-D...	KEEP AS NON CORE	Summary: IPI with human HLA-DR molecules (P04233, A0A0G4PYZ0). This is a cross-species (xenologous) interaction where E. coli DnaK binds human MHC class II molecules. This is an in vitro finding relevant to immunology but not to DnaK's native cellular function. Reason: Xenologous interaction with human HLA-DR. While demonstrating peptide-binding capacity of DnaK, this does not represent a native E. coli function.
GO:0005515 protein binding	IPI PMID:17968012 Analysis of sigma32 mutants defective in chaperone-mediated ...	MODIFY	Summary: IPI with RpoH/sigma32 (P0AGB3). Guisbert et al. (2008) analyzed sigma32 mutants defective in chaperone-mediated feedback control. DnaK binding to sigma32 is a central regulatory mechanism of the heat shock response. Reason: DnaK-sigma32 interaction is a functionally important regulatory interaction, better captured by GO:0016989 (sigma factor antagonist activity) which DnaK already has. GO:0005515 is uninformative. Proposed replacements: sigma factor antagonist activity
GO:0005515 protein binding	IPI PMID:18394994 Monitoring protein conformation along the pathway of chapero...	MARK AS OVER ANNOTATED	Summary: IPI with DnaJ (P08622). Lin et al. (2008) studied chaperonin-assisted folding and DnaK-DnaJ cooperation. Functionally meaningful co-chaperone interaction. Reason: DnaK-DnaJ interaction is already captured by GO:0051087 (protein-folding chaperone binding). Generic protein binding is uninformative.
GO:0005515 protein binding	IPI PMID:19439666 Solution conformation of wild-type E. coli Hsp70 (DnaK) chap...	MARK AS OVER ANNOTATED	Summary: IPI with DnaJ (P08622). Bertelsen et al. (2009) determined the solution structure of full-length DnaK complexed with ADP and substrate peptide. Important structural study showing domain dynamics. Reason: DnaK-DnaJ interaction already captured by more specific terms. This study's main contribution is structural understanding of the DnaK-ADP-substrate complex.
GO:0005515 protein binding	IPI PMID:19698713 DnaK-mediated association of ClpB to protein aggregates. A b...	MODIFY	Summary: IPI with ClpB (P63284). Winkler et al. (2009) showed DnaK mediates association of ClpB to protein aggregates, forming a bichaperone network at aggregate surfaces. This is a functionally important disaggregation-related interaction. Reason: DnaK-ClpB interaction is a functionally meaningful chaperone-chaperone interaction for protein disaggregation, better captured by GO:0031072 (heat shock protein binding). Proposed replacements: heat shock protein binding
GO:0005515 protein binding	IPI PMID:21474779 Species-specific collaboration of heat shock proteins (Hsp) ...	MARK AS OVER ANNOTATED	Summary: IPI with ClpB (P63284). Zietkiewicz et al. (2011) studied species-specific collaboration of Hsp70 and Hsp100 in thermotolerance and protein disaggregation. Reason: DnaK-ClpB interaction for disaggregation is already captured by more specific terms. GO:0005515 is uninformative.
GO:0005515 protein binding	IPI PMID:22065753 Heat shock protein 70 kDa chaperone/DnaJ cochaperone complex...	MARK AS OVER ANNOTATED	Summary: IPI with DnaJ (P08622). Ahmad et al. (2011) characterized the dynamic interface of the Hsp70/DnaJ cochaperone complex. Important structural study of co-chaperone interaction. Reason: DnaK-DnaJ interaction is a well-characterized co-chaperone interaction already annotated with GO:0051087. GO:0005515 adds nothing informative.
GO:0005515 protein binding	IPI PMID:23160352 Hsp70 proteins bind Hsp100 regulatory M domains to activate ...	MODIFY	Summary: IPI with ClpB (P63284). Seyffer et al. (2012) showed that Hsp70 (DnaK) proteins bind to Hsp100 regulatory M domains to activate AAA+ disaggregase activity at aggregate surfaces. Reason: Functionally important DnaK-ClpB interaction for disaggregation activation. Better captured by GO:0031072 (heat shock protein binding). Proposed replacements: heat shock protein binding
GO:0005515 protein binding	IPI PMID:24561554 The binary protein-protein interaction landscape of Escheric...	MARK AS OVER ANNOTATED	Summary: IPI from binary protein-protein interaction landscape study (Rajagopala et al. 2014). Large-scale Y2H screen detecting DnaK interactions with HtpG (P0A6Z3) and CbpA (P36659). Reason: Large-scale interaction screen. DnaK-HtpG and DnaK-CbpA are known chaperone interactions better captured by specific terms. GO:0005515 is uninformative.
GO:0005515 protein binding	IPI PMID:26545493 GroEL to DnaK chaperone network behind the stability modulat...	MODIFY	Summary: IPI with RpoH/sigma32 (P0AGB3). Masser et al. (2015) studied the GroEL-to-DnaK chaperone network behind sigma32 stability modulation. The DnaK-sigma32 interaction is a key regulatory mechanism. Reason: DnaK-sigma32 interaction for heat shock regulation is better captured by GO:0016989 (sigma factor antagonist activity). Proposed replacements: sigma factor antagonist activity
GO:0005515 protein binding	IPI PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	MODIFY	Summary: IPI with GrpE (P09372) from the crystal structure study of GrpE bound to the DnaK ATPase domain (Harrison et al. 1997). A dimer of GrpE binds asymmetrically to a single DnaK molecule. Reason: DnaK-GrpE is a core co-chaperone interaction essential for the DnaK functional cycle. Better captured by GO:0051087 (protein-folding chaperone binding). Proposed replacements: protein-folding chaperone binding Supporting Evidence: PMID:9103205 A dimer of GrpE binds asymmetrically to a single molecule of DnaK
GO:0009408 response to heat	IDA PMID:7023474 Positive regulatory gene for temperature-controlled proteins...	ACCEPT	Summary: Neidhardt and VanBogelen (1981) identified DnaK as a positive regulatory gene for temperature-controlled proteins. DnaK is one of the most highly induced heat shock proteins in E. coli. Reason: DnaK (Hsp70) is a major heat shock protein that is strongly induced upon heat stress. Response to heat is a core biological process for this gene.
GO:0009408 response to heat	IDA PMID:7900997 DnaK, DnaJ and GrpE form a cellular chaperone machinery capa...	ACCEPT	Summary: Schroder et al. (1993) demonstrated that DnaK, DnaJ, and GrpE form a chaperone machinery capable of repairing heat-induced protein damage. DnaK is essential for reactivation of heat-inactivated luciferase. Reason: Direct demonstration of DnaK function in the heat stress response, specifically repairing heat-damaged proteins. Supporting Evidence: PMID:7900997 DnaK, DnaJ and GrpE did not prevent luciferase inactivation, but were essential for its reactivation
GO:0009408 response to heat	IEP PMID:8349564 Characterization of twenty-six new heat shock genes of Esche...	ACCEPT	Summary: Chuang and Blattner (1993) characterized heat shock genes in E. coli and showed DnaK has expression kinetics typical of major heat shock proteins. IEP (expression pattern) evidence. Reason: DnaK is among the most well-characterized heat shock proteins. Its heat-induced expression pattern is consistent with its role in heat stress response. Supporting Evidence: PMID:8349564 In vivo expression kinetics of seven of eight examined new proteins were found to be similar to those of the four most studied heat shock proteins, DnaK, DnaJ, GroEL (MopA), and GroES (MopB)
GO:0034620 cellular response to unfolded protein	IDA PMID:2203539 The E. coli dnaK gene product, the hsp70 homolog, can reacti...	ACCEPT	Summary: Skowyra et al. (1990) showed DnaK protects RNA polymerase from heat inactivation and reactivates heat-inactivated/aggregated RNA polymerase. This demonstrates DnaK's role in cellular response to unfolded proteins. Reason: DnaK is a central effector of the cellular response to unfolded proteins, both preventing aggregation and reactivating misfolded/aggregated proteins. Supporting Evidence: PMID:2203539 the dnaK gene product, protects the host RNA polymerase enzyme from heat inactivation in an ATP-independent reaction...heat-inactivated and aggregated RNA polymerase is both disaggregated and reactivated following simultaneous incubation with DnaK protein and hydrolyzable ATP
GO:0034620 cellular response to unfolded protein	IDA PMID:7900997 DnaK, DnaJ and GrpE form a cellular chaperone machinery capa...	ACCEPT	Summary: Schroder et al. (1993) showed DnaK/DnaJ/GrpE repair heat-damaged proteins. DnaJ associates with denatured luciferase, targets DnaK to the substrate, and together they prevent aggregation and enable reactivation. Reason: DnaK is essential for the cellular response to unfolded/denatured proteins. Supporting Evidence: PMID:7900997 DnaJ associated with denatured luciferase, targeted DnaK to the substrate and co-operated with DnaK to prevent luciferase aggregation at 42 degrees C
GO:0043335 protein unfolding	IDA PMID:20953191 The kinetic parameters and energy cost of the Hsp70 chaperon...	ACCEPT	Summary: Sharma et al. (2010) characterized DnaK as a polypeptide unfoldase, showing that Hsp70 consumes ATP to unfold a stably misfolded protein into an intermediate that spontaneously refolds to the native state. One DnaK consumed five ATPs to unfold one misfolded protein. Reason: DnaK's unfoldase activity is a key mechanistic feature of its chaperone function. By unfolding stably misfolded species, DnaK gives them another chance to fold correctly. This is a genuine and important aspect of DnaK function. Supporting Evidence: PMID:20953191 one Hsp70 molecule consumed five ATPs to effectively unfold a single misfolded protein into an intermediate that, upon chaperone dissociation, spontaneously refolded to the native state
GO:0140662 ATP-dependent protein folding chaperone	IDA PMID:2203539 The E. coli dnaK gene product, the hsp70 homolog, can reacti...	ACCEPT	Summary: Skowyra et al. (1990) showed DnaK reactivates heat-inactivated RNA polymerase in an ATP hydrolysis-dependent manner. This directly demonstrates ATP-dependent protein folding chaperone activity. Reason: Core molecular function of DnaK. GO:0140662 is the most specific and accurate MF term for DnaK -- it is a child of GO:0044183 (protein folding chaperone) combined with ATP dependence, exactly matching DnaK's mechanism. Supporting Evidence: PMID:2203539 heat-inactivated and aggregated RNA polymerase is both disaggregated and reactivated following simultaneous incubation with DnaK protein and hydrolyzable ATP
GO:0140662 ATP-dependent protein folding chaperone	IDA PMID:7937953 The ATP hydrolysis-dependent reaction cycle of the Escherich...	ACCEPT	Summary: Szabo et al. (1994) defined the complete ATP hydrolysis-dependent reaction cycle of the DnaK/DnaJ/GrpE system mediating folding of denatured luciferase. They showed multiple rounds of ATP-dependent binding and release are required for efficient folding. Reason: Definitive demonstration of DnaK's ATP-dependent chaperone cycle. This paper established the mechanistic framework for the DnaK system. Supporting Evidence: PMID:7937953 A single cycle of binding and release leads to folding of only a fraction of luciferase molecules. Several rounds of ATP-dependent interaction with DnaK and DnaJ are required for fully efficient folding
GO:1990169 stress response to copper ion	IMP PMID:35289645 Copper Induces Protein Aggregation, a Toxic Process Compensa...	KEEP AS NON CORE	Summary: Zuily et al. (2022) showed copper induces protein aggregation in E. coli and that molecular chaperones including DnaK compensate for this toxicity. IMP evidence indicates DnaK mutant phenotype is relevant to copper stress. Reason: Copper-induced protein aggregation triggers the chaperone response, with DnaK playing a compensatory role. This is a genuine but secondary function -- DnaK's chaperone activity is recruited to handle copper-induced misfolding, rather than copper stress response being an evolved function per se.
GO:0051087 protein-folding chaperone binding	IPI PMID:21525416 Heat shock protein 90 from Escherichia coli collaborates wit...	ACCEPT	Summary: Genest et al. (2011) showed E. coli Hsp90 (HtpG, P0A6Z3) collaborates with the DnaK chaperone system in client protein remodeling. DnaK and HtpG interact in vivo and in vitro. Reason: DnaK-HtpG (Hsp90) interaction is a functionally relevant chaperone-chaperone binding event important for client remodeling. GO:0051087 appropriately captures this. Supporting Evidence: PMID:21525416 Results indicate that E. coli Hsp90 and DnaK interact in vivo and in vitro, providing additional evidence to suggest that E. coli Hsp90 and the DnaK system function together
GO:0005515 protein binding	IPI PMID:30442809 Protein assemblies ejected directly from native membranes yi...	MARK AS OVER ANNOTATED	Summary: IPI with OmpA (P0A910) from native membrane mass spectrometry study (Chorev et al. 2018). DnaK was found associated with membrane protein complexes. Reason: DnaK association with membrane protein OmpA likely reflects chaperone function at the membrane. GO:0005515 is uninformative for a general chaperone.
GO:0005524 ATP binding	IDA PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	ACCEPT	Summary: Harrison et al. (1997) solved the crystal structure of GrpE bound to the nucleotide-free ATPase domain of DnaK, which also provided structural context for ATP binding. The CAFA annotation cites this as IDA evidence for ATP binding. Reason: ATP binding is a core function of DnaK's N-terminal nucleotide-binding domain (NBD). Well-supported by structural and biochemical data. Supporting Evidence: PMID:9103205 The structure of the nucleotide-free ATPase domain in complex with GrpE resembles closely that of the nucleotide-bound mammalian Hsp70 homolog
GO:0006457 protein folding	IDA PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	ACCEPT	Summary: CAFA annotation citing the GrpE-DnaK crystal structure paper. While this paper primarily addresses structure, the DnaK system's role in protein folding is implicit in the functional context of the chaperone cycle. Reason: Protein folding is the core biological process of DnaK. While this specific paper is primarily structural, it provides context for the nucleotide cycle that drives folding.
GO:0032991 protein-containing complex	IDA PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	ACCEPT	Summary: Harrison et al. (1997) solved the crystal structure of the GrpE dimer bound to DnaK, demonstrating a stable protein-containing complex. DnaK forms functional complexes with its co-chaperones. Reason: DnaK forms well-characterized complexes with GrpE (crystallized) and DnaJ. The DnaK-GrpE complex is a bona fide protein-containing complex. Supporting Evidence: PMID:9103205 A dimer of GrpE binds asymmetrically to a single molecule of DnaK
GO:0051082 unfolded protein binding	IDA PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	MODIFY	Summary: CAFA annotation. The GrpE-DnaK crystal structure paper does describe DnaK's substrate- binding domain and its interaction with peptide substrates. However, GO:0051082 is proposed for obsoletion, and DnaK's function is better described as ATP-dependent protein folding chaperone (GO:0140662). Reason: GO:0051082 is proposed for obsoletion (go-ontology#30962). DnaK's substrate binding is mechanistically part of its foldase cycle. The appropriate replacement is GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent protein folding chaperone), both of which DnaK already has. Proposed replacements: ATP-dependent protein folding chaperone
GO:0051087 protein-folding chaperone binding	IPI PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	ACCEPT	Summary: IPI with DnaJ (P08622) from the GrpE-DnaK crystal structure study. While the primary focus is GrpE-DnaK, DnaJ interaction is discussed in the context of the chaperone cycle. Reason: DnaK binding to co-chaperones DnaJ and GrpE is a core functional interaction. GO:0051087 appropriately captures chaperone-chaperone binding.
GO:0065003 protein-containing complex assembly	IDA PMID:9103205 Crystal structure of the nucleotide exchange factor GrpE bou...	KEEP AS NON CORE	Summary: CAFA annotation citing the GrpE-DnaK crystal structure. The complex assembly (DnaK with GrpE dimer) was demonstrated crystallographically. However, this is a byproduct of DnaK's chaperone cycle rather than a primary function. Reason: DnaK does assemble into complexes with its co-chaperones (GrpE dimer, DnaJ), but complex assembly is not DnaK's primary function -- it is part of the chaperone mechanism. This is non-core.
GO:0016234 inclusion body	IDA PMID:15866952 Localization of chaperones DnaK and GroEL in bacterial inclu...	ACCEPT	Summary: Carrio and Villaverde (2005) showed by immunostaining and electron microscopy that DnaK localizes to the solvent-exposed surface of bacterial inclusion bodies. This represents DnaK's quality control function at sites of protein aggregation. Reason: DnaK localization to inclusion body surfaces is consistent with its role in protein quality control. It is recruited to aggregates where it acts to resolubilize and refold misfolded proteins. Supporting Evidence: PMID:15866952 chaperones DnaK and GroEL have been identified at the solvent-exposed surface of bacterial inclusion bodies and entrapped within these aggregates, respectively
GO:0005515 protein binding	IPI PMID:2522091 Escherichia coli DnaK and GrpE heat shock proteins interact ...	MODIFY	Summary: Johnson et al. (1989) demonstrated DnaK and GrpE interact both in vivo and in vitro by coimmunoprecipitation. This was one of the earliest demonstrations of the DnaK-GrpE functional interaction. Reason: DnaK-GrpE interaction is a core co-chaperone interaction better captured by GO:0051087 (protein-folding chaperone binding) rather than generic protein binding. Proposed replacements: protein-folding chaperone binding Supporting Evidence: PMID:2522091 Coimmunoprecipitation of DnaK+ and GrpE+ proteins from cell lysates with anti-DnaK antibodies demonstrated their interaction in vitro
GO:0016989 sigma factor antagonist activity	IDA PMID:8599944 A cycle of binding and release of the DnaK, DnaJ and GrpE ch...	ACCEPT	Summary: Gamer et al. (1996) showed DnaK and DnaJ cooperatively bind free sigma32 and inhibit its transcriptional activity in a cycle of binding and release regulated by GrpE and ATP. This constitutes sigma factor antagonist activity. Reason: DnaK directly inhibits sigma32 activity by binding it and preventing its association with RNA polymerase. This is an important regulatory function and represents a non-core but well-characterized MF of DnaK. The chaperone-mediated feedback control of the heat shock response depends on this activity. Supporting Evidence: PMID:8599944 DnaK and DnaJ cooperatively inhibit sigma32 activity in heat shock gene transcription and GrpE partially reverses this inhibition
GO:0005829 cytosol	IDA PMID:15911532 Localization, annotation, and comparison of the Escherichia ...	ACCEPT	Summary: IDA localization study (Sato et al. 2005) confirming DnaK is present in the E. coli cytosol under different growth conditions. Reason: Cytosol is the primary localization of DnaK, confirmed by multiple independent studies.
GO:0005829 cytosol	IDA PMID:18304323 Protein abundance profiling of the Escherichia coli cytosol.	ACCEPT	Summary: IDA from protein abundance profiling of the E. coli cytosol (Ishihama et al. 2008). DnaK is one of the most abundant cytosolic proteins. Reason: Confirms cytosolic localization. DnaK is one of the most abundant proteins in the E. coli cytosol. Supporting Evidence: PMID:18304323 we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins
GO:0044183 protein folding chaperone	IDA PMID:10380927 Polypeptide flux through bacterial Hsp70: DnaK cooperates wi...	ACCEPT	Summary: Teter et al. (1999) showed DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides under nonstress conditions, demonstrating its role as a de novo protein folding chaperone. Combined deletion of trigger factor and DnaK is lethal. Reason: Definitive demonstration of DnaK as a de novo protein folding chaperone for nascent polypeptides. This is a core molecular function. Supporting Evidence: PMID:10380927 DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides, with a preference for chains larger than 30 kDa...Combined deletion of the trigger factor and DnaK genes is lethal under normal growth conditions
GO:0005524 ATP binding	IDA PMID:7776367 The role of ATP in the functional cycle of the DnaK chaperon...	ACCEPT	Summary: McCarty et al. (1995) characterized the ATP hydrolysis cycle of DnaK, showing that ATP-bound DnaK is the primary form initiating substrate interaction. Reason: Core function. ATP binding to DnaK's NBD drives its conformational cycle. This paper provided detailed kinetic characterization of the nucleotide cycle. Supporting Evidence: PMID:7776367 The rapid binding kinetics lead to the conclusion that ATP-bound DnaK is the primary form initiating interaction with substrates for chaperone activity
GO:0043531 ADP binding	IDA PMID:19439666 Solution conformation of wild-type E. coli Hsp70 (DnaK) chap...	ACCEPT	Summary: Bertelsen et al. (2009) determined the solution conformation of wild-type DnaK complexed with ADP and substrate peptide. ADP binding stabilizes the closed-lid conformation of the substrate-binding domain. Reason: ADP binding is an integral part of the DnaK chaperone cycle. In the ADP-bound state, DnaK has high affinity for substrate with slow exchange rates. Supporting Evidence: PMID:19439666 an experimental structure for wild-type, full-length DnaK, complexed with the peptide NRLLLTG and with ADP
GO:0043531 ADP binding	IDA PMID:7776367 The role of ATP in the functional cycle of the DnaK chaperon...	ACCEPT	Summary: McCarty et al. (1995) characterized DnaK's nucleotide binding properties, including ADP binding and its role in the functional cycle. Reason: ADP binding is essential for the DnaK chaperone cycle. GrpE stimulates ADP release, which is a key regulatory step.
GO:0051082 unfolded protein binding	IDA PMID:9145101 Interaction of Hsp70 chaperones with substrates.	MODIFY	Summary: Rudiger et al. (1997) characterized DnaK interaction with peptide substrates, defining the substrate-binding motif: DnaK recognizes extended peptide strands composed of hydrophobic residues. This directly demonstrates binding to unfolded protein segments. However, GO:0051082 is proposed for obsoletion. Reason: GO:0051082 is proposed for obsoletion (go-ontology#30962). While this paper directly demonstrates DnaK binding to unfolded peptide segments, this binding is mechanistically part of DnaK's foldase activity. The correct replacement is GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent protein folding chaperone). DnaK can also act as a holdase in some contexts (PMID:2203539), but the holdase NTR is pending. Proposed replacements: ATP-dependent protein folding chaperone Supporting Evidence: PMID:9145101 DnaK recognizes extended peptide strands composed of up to five consecutive hydrophobic residues within and positively charged residues outside the substrate binding cavity
GO:0008270 zinc ion binding	IDA PMID:11985624 Systematic search for zinc-binding proteins in Escherichia c...	UNDECIDED	Summary: Katayama et al. (2002) identified DnaK as a zinc-binding protein in a systematic search for zinc-binding proteins in E. coli using radioactive Zn(II) binding assay. DnaK was among nine newly identified zinc-binding proteins. Reason: The zinc-binding activity was detected in a systematic proteome-wide screen using radioactive zinc. While DnaK was identified, the biological significance of zinc binding to DnaK is unclear. DnaK does not contain a canonical zinc-finger or zinc-binding motif. This may represent adventitious metal binding rather than a biologically relevant function. There is no known role for zinc in DnaK's chaperone mechanism. Supporting Evidence: PMID:11985624 nine zinc-binding proteins were newly identified including: acetate kinase (AckA), DnaK, serine hydroxymethyltransferase (GlyA)
GO:0005737 cytoplasm	HDA PMID:16858726 A complexomic study of Escherichia coli using two-dimensiona...	ACCEPT	Summary: HDA annotation from complexomic study (Maddalo et al. 2006) confirming cytoplasmic localization of DnaK. Reason: Cytoplasm is the established localization of DnaK, consistent with multiple studies.
GO:0016020 membrane	HDA PMID:16858726 A complexomic study of Escherichia coli using two-dimensiona...	KEEP AS NON CORE	Summary: HDA annotation from complexomic study detecting DnaK in membrane fractions. UniProt describes DnaK as a peripheral inner membrane protein (PMID:16079137). This is a secondary localization. Reason: DnaK is primarily cytosolic but is also found associated with membranes as a peripheral protein. This is a secondary localization, not the primary one.

Core Functions

DnaK is the E. coli HSP70 homolog that functions as an ATP-dependent protein folding chaperone (foldase). It binds unfolded polypeptide segments, undergoes ATP hydrolysis- driven conformational changes (with DnaJ and GrpE co-chaperones), and releases substrates to allow folding. Multiple rounds of binding and release are required for efficient folding of most substrates (PMID:7937953). DnaK also protects proteins from heat inactivation (holdase function, ATP-independent; PMID:2203539) and cooperates with trigger factor to chaperone nascent polypeptides (PMID:10380927).

Molecular Function:

ATP-dependent protein folding chaperone

Directly Involved In:

protein refolding protein folding cellular response to unfolded protein response to heat protein unfolding

Cellular Locations:

cytosol inclusion body

Supporting Evidence:

PMID:7937953
Several rounds of ATP-dependent interaction with DnaK and DnaJ are required for fully efficient folding
PMID:10380927
DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides, with a preference for chains larger than 30 kDa

DnaK inhibits sigma32 (RpoH) transcriptional activity by direct binding, constituting the chaperone-mediated negative feedback loop of the heat shock response. DnaK and DnaJ cooperatively sequester free sigma32, preventing its association with RNA polymerase. GrpE and ATP drive the release cycle (PMID:8599944).

Molecular Function:

sigma factor antagonist activity

Directly Involved In:

negative regulation of DNA-templated transcription

Cellular Locations:

cytosol

Supporting Evidence:

PMID:8599944
DnaK and DnaJ cooperatively inhibit sigma32 activity in heat shock gene transcription

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000108

Automatic assignment of GO terms using logical inference, based on on inter-ontology links

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10380927

Polypeptide flux through bacterial Hsp70: DnaK cooperates with trigger factor in chaperoning nascent chains.

DnaK functions as a de novo protein folding chaperone, transiently associating with nascent polypeptides under nonstress conditions.

"under nonstress conditions DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides, with a preference for chains larger than 30 kDa"

PMID:10521435

Structural features required for the interaction of the Hsp70 molecular chaperone DnaK with its cochaperone DnaJ.

PMID:11985624

Systematic search for zinc-binding proteins in Escherichia coli.

DnaK identified as a zinc-binding protein in systematic proteome-wide screen. Biological significance unclear.

"nine zinc-binding proteins were newly identified including: acetate kinase (AckA), DnaK, serine hydroxymethyltransferase (GlyA)"

PMID:15690043

Interaction network containing conserved and essential protein complexes in Escherichia coli.

PMID:15866952

Localization of chaperones DnaK and GroEL in bacterial inclusion bodies.

DnaK localizes to the solvent-exposed surface of bacterial inclusion bodies.

"chaperones DnaK and GroEL have been identified at the solvent-exposed surface of bacterial inclusion bodies and entrapped within these aggregates, respectively"

PMID:15911532

Localization, annotation, and comparison of the Escherichia coli K-12 proteome under two states of growth.

PMID:16139413

Analysis of the Escherichia coli RNA degradosome composition by a proteomic approach.

PMID:16606699

Large-scale identification of protein-protein interaction of Escherichia coli K-12.

PMID:16858726

A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis.

PMID:17357109

70-kDa heat shock proteins: specific interactions with HLA-DR molecules and their peptide fragments.

PMID:17968012

Analysis of sigma32 mutants defective in chaperone-mediated feedback control reveals unexpected complexity of the heat shock response.

PMID:18304323

Protein abundance profiling of the Escherichia coli cytosol.

PMID:18394994

Monitoring protein conformation along the pathway of chaperonin-assisted folding.

PMID:19439666

Solution conformation of wild-type E. coli Hsp70 (DnaK) chaperone complexed with ADP and substrate.

Solution structure of full-length DnaK in ADP-substrate bound state. NBD and SBD are loosely linked with dynamic relative orientation.

"an experimental structure for wild-type, full-length DnaK, complexed with the peptide NRLLLTG and with ADP"

PMID:19698713

DnaK-mediated association of ClpB to protein aggregates. A bichaperone network at the aggregate surface.

DnaK mediates recruitment of ClpB disaggregase to protein aggregates.

"ClpB binding strictly depends on previous DnaK association with the aggregate... DnaK mediates ClpB interaction with the aggregate surface"

PMID:20953191

The kinetic parameters and energy cost of the Hsp70 chaperone as a polypeptide unfoldase.

DnaK functions as a polypeptide unfoldase, consuming 5 ATPs to unfold one misfolded protein into a spontaneously refoldable intermediate.

"one Hsp70 molecule consumed five ATPs to effectively unfold a single misfolded protein into an intermediate that, upon chaperone dissociation, spontaneously refolded to the native state"

PMID:21474779

Species-specific collaboration of heat shock proteins (Hsp) 70 and 100 in thermotolerance and protein disaggregation.

PMID:21525416

Heat shock protein 90 from Escherichia coli collaborates with the DnaK chaperone system in client protein remodeling.

E. coli Hsp90 (HtpG) and DnaK interact and collaborate in client protein remodeling.

"E. coli Hsp90 and DnaK interact in vivo and in vitro, providing additional evidence to suggest that E. coli Hsp90 and the DnaK system function together"

PMID:2203539

The E. coli dnaK gene product, the hsp70 homolog, can reactivate heat-inactivated RNA polymerase in an ATP hydrolysis-dependent manner.

DnaK protects RNA polymerase from heat inactivation (ATP-independent holdase) and reactivates aggregated RNA polymerase (ATP-dependent foldase/disaggregase).

"the dnaK gene product, protects the host RNA polymerase enzyme from heat inactivation in an ATP-independent reaction...heat-inactivated and aggregated RNA polymerase is both disaggregated and reactivated following simultaneous incubation with DnaK protein and hydrolyzable ATP"

PMID:22065753

Heat shock protein 70 kDa chaperone/DnaJ cochaperone complex employs an unusual dynamic interface.

PMID:23160352

Hsp70 proteins bind Hsp100 regulatory M domains to activate AAA+ disaggregase at aggregate surfaces.

DnaK activates ClpB disaggregase by binding its regulatory M domain.

"DnaK directly binds M-domain motif 2, increasing ClpB ATPase activity to unleash high ClpB threading power"

PMID:24561554

The binary protein-protein interaction landscape of Escherichia coli.

PMID:2522091

Escherichia coli DnaK and GrpE heat shock proteins interact both in vivo and in vitro.

DnaK and GrpE functionally interact, shown by genetic suppression and coimmunoprecipitation.

"Coimmunoprecipitation of DnaK+ and GrpE+ proteins from cell lysates with anti-DnaK antibodies demonstrated their interaction in vitro"

PMID:26545493

GroEL to DnaK chaperone network behind the stability modulation of σ(32) at physiological temperature in Escherichia coli.

GroEL acts upstream of DnaK in an ordered network that modulates sigma32 stability at physiological temperature.

"neither DnaK nor GroEL singly can modulate sigma(32) stability in vivo; there is an ordered network between them, where GroEL acts upstream of DnaK"

PMID:30442809

Protein assemblies ejected directly from native membranes yield complexes for mass spectrometry.

PMID:35289645

Copper Induces Protein Aggregation, a Toxic Process Compensated by Molecular Chaperones.

Copper induces protein aggregation and DnaK compensates for this toxicity.

"coli strains lacking the cytosolic chaperone DnaK or trigger factor are highly sensitive to copper stress"

PMID:7023474

Positive regulatory gene for temperature-controlled proteins in Escherichia coli.

PMID:7776367

The role of ATP in the functional cycle of the DnaK chaperone system.

Detailed kinetic characterization of DnaK's ATPase cycle. ATP-bound DnaK initiates substrate interaction; DnaJ stimulates ATP hydrolysis to stabilize substrate binding.

"DnaK ATPase was stimulated by substrates (ninefold) and DnaJ (13-fold) through stimulation of the rate limiting step, gamma-phosphate cleavage"

PMID:7900997

DnaK, DnaJ and GrpE form a cellular chaperone machinery capable of repairing heat-induced protein damage.

DnaK/DnaJ/GrpE system repairs heat-damaged luciferase both in vivo and in vitro. DnaJ targets DnaK to denatured substrates. ATP required for reactivation.

"DnaK, DnaJ and GrpE did not prevent luciferase inactivation, but were essential for its reactivation"

PMID:7937953

The ATP hydrolysis-dependent reaction cycle of the Escherichia coli Hsp70 system DnaK, DnaJ, and GrpE.

Defined the four-step chaperone cycle: substrate-DnaJ interaction, DnaK ATP hydrolysis and complex formation, GrpE-mediated ADP release, ATP-triggered substrate release. Multiple rounds needed for efficient folding.

"Several rounds of ATP-dependent interaction with DnaK and DnaJ are required for fully efficient folding"

PMID:8349564

Characterization of twenty-six new heat shock genes of Escherichia coli.

PMID:8599944

A cycle of binding and release of the DnaK, DnaJ and GrpE chaperones regulates activity of the Escherichia coli heat shock transcription factor sigma32.

DnaK/DnaJ bind free sigma32 and inhibit its transcriptional activity. GrpE/ATP drive release cycle. Central regulatory element of the heat shock response.

"DnaK and DnaJ cooperatively inhibit sigma32 activity in heat shock gene transcription and GrpE partially reverses this inhibition"

PMID:9103205

Crystal structure of the nucleotide exchange factor GrpE bound to the ATPase domain of the molecular chaperone DnaK.

GrpE dimer binds asymmetrically to one DnaK molecule. Conformational change in DnaK NBD inconsistent with tight nucleotide binding explains GrpE's exchange mechanism.

"A dimer of GrpE binds asymmetrically to a single molecule of DnaK"

PMID:9145101

Interaction of Hsp70 chaperones with substrates.

DnaK recognizes extended peptide strands with hydrophobic core and flanking positive charges. Defines substrate-binding specificity of Hsp70.

"DnaK recognizes extended peptide strands composed of up to five consecutive hydrophobic residues within and positively charged residues outside the substrate binding cavity"

📚 Additional Documentation

Deep Research Bioreason

(DnaK-deep-research-bioreason.md)

BioReason Chat Export

Exported on March 22, 2026 at 02:52 AM

Organism: Escherichia coli

Sequence:

MGKIIGIDLGTTNSCVAIMDGTTPRVLENAEGDRTTPSIIAYTQDGETLVGQPAKRQAVTNPQNTLFAIKRLIGRRFQDEEVQRDVSIMPFKIIAADNGDAWVEVKGQKMAPPQISAEVLKKMKKTAEDYLGEPVTEAVITVPAYFNDAQRQATKDAGRIAGLEVKRIINEPTAAALAYGLDKGTGNRTIAVYDLGGGTFDISIIEIDEVDGEKTFEVLATNGDTHLGGEDFDSRLINYLVEEFKKDQGIDLRNDPLAMQRLKEAAEKAKIELSSAQQTDVNLPYITADATGPKHMNIKVTRAKLESLVEDLVNRSIEPLKVALQDAGLSVSDIDDVILVGGQTRMPMVQKKVAEFFGKEPRKDVNPDEAVAIGAAVQGGVLTGDVKDVLLLDVTPLSLGIETMGGVMTTLIAKNTTIPTKHSQVFSTAEDNQSAVTIHVLQGERKRAADNKSLGQFNLDGINPAPRGMPQIEVTFDIDADGILHVSAKDKNSGKEQKITIKASSGLNEDEIQKMVRDAEANAEADRKFEELVQTRNQGDHLLHSTRKQVEEAGDKLPADDKTAIESALTALETALKGEDKAAIEAKMQELAQVSQKLMEIAQQQHAQQQTAGADASANNAKDDDVVDAEFEEVKDKK

Thinking Trace

I begin with the InterPro architecture, which is diagnostic for an Hsp70/DnaK-type chaperone. IPR012725 (Chaperone DnaK family, residues 1–634) and IPR013126 (Heat shock protein 70 family, residues 4–602) blanket nearly the entire sequence, establishing membership in the canonical ATP-dependent heat-shock chaperone family. The N-terminal half is reinforced by IPR043129 (ATPase, nucleotide binding domain homologous superfamily, residues 4–382) and the conserved catalytic signature IPR018181 (Heat shock protein 70 conserved site, residues 7–351), which together create an adenine nucleotide–binding pocket and P-loop–like/NBD elements that drive ATP hydrolysis. This ATPase core couples nucleotide state to conformational switching. The C-terminal half is organized by IPR029047 (Heat shock protein 70kD peptide-binding domain superfamily, residues 381–539) followed by IPR029048 (Heat shock protein 70kD C-terminal domain superfamily, residues 507–607). This arrangement forms the canonical two-lobed substrate/peptide-binding module and its C-terminal lid that clamp onto exposed hydrophobic segments of non-native proteins. The order—NBD (4–382) leading into the SBD (381–539) and capped by the C-terminal lid (507–607)—is the hallmark DnaK/Hsp70 mechanism: ATP binding opens the substrate-binding cleft, while ATP hydrolysis triggers tight substrate capture and release.

This architecture dictates molecular function. The NBD signatures (IPR043129, IPR018181) necessitate ATP binding and hydrolysis, so the protein must execute ATPase-coupled cycles that regulate client affinity; thus ATP-dependent chaperone activity emerges directly from the fold. The peptide-binding superfamily (IPR029047) and C-terminal lid (IPR029048) enforce selective recognition of non-native polypeptides. Together, these features define the molecular activities: ATP binding and ATPase activity that power an unfolded-protein binding chaperone cycle.

From function to process, an Hsp70/DnaK machine resolves misfolded states that accumulate during stress and normal proteostasis. By clamping and releasing client segments in an ATP-coupled manner, it promotes productive folding pathways and prevents aggregation—this is the essence of protein folding and refolding. In bacteria, DnaK collaborates with co-chaperones to triage clients between refolding and degradation, thereby sustaining proteome integrity during heat shock and other insults.

Cellular location follows from the soluble, cytosolic architecture: there are no transmembrane segments or secretion signals in the InterPro profile, and the soluble ATPase/peptide-binding assembly is characteristic of a cytoplasmic chaperone. Therefore, the operational compartment is the cytoplasm.

These mechanistic elements suggest specific partners and a working model. The NBD-driven cycle requires J-domain cochaperones (e.g., DnaJ) that stimulate ATP hydrolysis and nucleotide exchange factors (e.g., GrpE) that reset the cycle. Consequently, I hypothesize a functional ensemble: DnaJ family cochaperones deliver clients and accelerate turnover; GrpE catalyzes ADP release to re-prime ATP binding; accessory factors such as trigger factor or ribosome-associated modules may funnel nascent chains into this pathway. In the cytoplasm, this chaperone hub captures non-native substrates, refolds them through iterative ATP-driven clamping, and returns folded proteins to their proper cellular locales.

Functional Summary

A cytoplasmic ATP-dependent heat-shock chaperone that cycles between nucleotide-bound states to capture and release exposed hydrophobic segments on non-native polypeptides. By coupling an ATPase engine to a peptide-binding clamp, it stabilizes misfolded intermediates, prevents aggregation, and promotes productive refolding during stress and normal proteostasis. In bacteria, it operates with cognate cochaperones to triage clients toward recovery or degradation, thereby preserving proteome integrity in the cytoplasm.

UniProt Summary

Acts as a chaperone.

InterPro Domains

Chaperone DnaK (IPR012725, family) — residues 1-634
Heat shock protein 70 family (IPR013126, family) — residues 4-602
ATPase, nucleotide binding domain (IPR043129, homologous_superfamily) — residues 4-382
Heat shock protein 70, conserved site (IPR018181, conserved_site) — residues 7-351
Heat shock protein 70kD, peptide-binding domain superfamily (IPR029047, homologous_superfamily) — residues 381-539
Heat shock protein 70kD, C-terminal domain superfamily (IPR029048, homologous_superfamily) — residues 507-607

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), structural molecule activity (GO:0005515), chaperone binding (GO:0051087), protein domain specific binding (GO:0019904)

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), localization (GO:0051179), establishment of localization (GO:0051234), cellular localization (GO:0051641), transmembrane transport (GO:0055085), macromolecule localization (GO:0033036), cellular macromolecule localization (GO:0070727), establishment of localization in cell (GO:0051649), intracellular transport (GO:0046907), establishment of protein localization (GO:0045184), protein transmembrane transport (GO:0071806), transport (GO:0006810), organic substance transport (GO:0071702), intracellular protein transmembrane transport (GO:0065002), intracellular protein transport (GO:0006886), nitrogen compound transport (GO:0071705), protein localization (GO:0008104), protein transport (GO:0015031)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), protein-containing complex (GO:0032991), cytosol (GO:0005829), cytoplasm (GO:0005622), cytoplasm (GO:0005737), intracellular protein-containing complex (GO:0140535), chaperone complex (GO:0101031)

Generated by BioReason

Deep Research Bioreason Rl

(DnaK-deep-research-bioreason-rl.md)

BioReason Chat Export

Exported on March 22, 2026 at 02:52 AM

Organism: Escherichia coli

Sequence:

MGKIIGIDLGTTNSCVAIMDGTTPRVLENAEGDRTTPSIIAYTQDGETLVGQPAKRQAVTNPQNTLFAIKRLIGRRFQDEEVQRDVSIMPFKIIAADNGDAWVEVKGQKMAPPQISAEVLKKMKKTAEDYLGEPVTEAVITVPAYFNDAQRQATKDAGRIAGLEVKRIINEPTAAALAYGLDKGTGNRTIAVYDLGGGTFDISIIEIDEVDGEKTFEVLATNGDTHLGGEDFDSRLINYLVEEFKKDQGIDLRNDPLAMQRLKEAAEKAKIELSSAQQTDVNLPYITADATGPKHMNIKVTRAKLESLVEDLVNRSIEPLKVALQDAGLSVSDIDDVILVGGQTRMPMVQKKVAEFFGKEPRKDVNPDEAVAIGAAVQGGVLTGDVKDVLLLDVTPLSLGIETMGGVMTTLIAKNTTIPTKHSQVFSTAEDNQSAVTIHVLQGERKRAADNKSLGQFNLDGINPAPRGMPQIEVTFDIDADGILHVSAKDKNSGKEQKITIKASSGLNEDEIQKMVRDAEANAEADRKFEELVQTRNQGDHLLHSTRKQVEEAGDKLPADDKTAIESALTALETALKGEDKAAIEAKMQELAQVSQKLMEIAQQQHAQQQTAGADASANNAKDDDVVDAEFEEVKDKK

Thinking Trace

Functional Summary

UniProt Summary

Acts as a chaperone.

InterPro Domains

Chaperone DnaK (IPR012725, family) — residues 1-634
Heat shock protein 70 family (IPR013126, family) — residues 4-602
ATPase, nucleotide binding domain (IPR043129, homologous_superfamily) — residues 4-382
Heat shock protein 70, conserved site (IPR018181, conserved_site) — residues 7-351
Heat shock protein 70kD, peptide-binding domain superfamily (IPR029047, homologous_superfamily) — residues 381-539
Heat shock protein 70kD, C-terminal domain superfamily (IPR029048, homologous_superfamily) — residues 507-607

GO Terms

Generated by BioReason

Deep Research Falcon

(DnaK-deep-research-falcon.md)

provider: falcon
model: Edison Scientific Literature
cached: false
start_time: '2026-03-22T17:57:47.961844'
end_time: '2026-03-22T18:08:42.466317'
duration_seconds: 654.5
template_file: templates/gene_research_go_focused.md
template_variables:
organism: ECOLI
gene_id: DnaK
gene_symbol: dnaK
uniprot_accession: P0A6Y8
protein_description: 'RecName: Full=Chaperone protein DnaK; AltName: Full=HSP70;
AltName: Full=Heat shock 70 kDa protein; AltName: Full=Heat shock protein 70;'
gene_info: Name=dnaK; Synonyms=groP, grpF, seg; OrderedLocusNames=b0014, JW0013;
organism_full: Escherichia coli (strain K12).
protein_family: Belongs to the heat shock protein 70 family. .
protein_domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS.
(IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)
provider_config:
timeout: 600
max_retries: 3
parameters:
allowed_domains: []
temperature: 0.1
citation_count: 30

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P0A6Y8
Protein Description: RecName: Full=Chaperone protein DnaK; AltName: Full=HSP70; AltName: Full=Heat shock 70 kDa protein; AltName: Full=Heat shock protein 70;
Gene Information: Name=dnaK; Synonyms=groP, grpF, seg; OrderedLocusNames=b0014, JW0013;
Organism (full): Escherichia coli (strain K12).
Protein Family: Belongs to the heat shock protein 70 family. .
Key Domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS. (IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "dnaK" matches the protein description above
Verify the organism is correct: Escherichia coli (strain K12).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'dnaK' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene dnaK (gene ID: DnaK, UniProt: P0A6Y8) in ECOLI.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P0A6Y8
Protein Description: RecName: Full=Chaperone protein DnaK; AltName: Full=HSP70; AltName: Full=Heat shock 70 kDa protein; AltName: Full=Heat shock protein 70;
Gene Information: Name=dnaK; Synonyms=groP, grpF, seg; OrderedLocusNames=b0014, JW0013;
Organism (full): Escherichia coli (strain K12).
Protein Family: Belongs to the heat shock protein 70 family. .
Key Domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS. (IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "dnaK" matches the protein description above
Verify the organism is correct: Escherichia coli (strain K12).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

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Research Target:

Please provide a comprehensive research report on the gene dnaK (gene ID: DnaK, UniProt: P0A6Y8) in ECOLI.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Research report: Functional annotation of dnaK (UniProt P0A6Y8) in Escherichia coli K-12

1) Target verification (mandatory)

The gene symbol dnaK in this report refers specifically to Escherichia coli (strain K-12) Chaperone protein DnaK, the canonical bacterial Hsp70 family member, with UniProt accession P0A6Y8. This identity is explicitly tied to UniProt P0A6Y8 in mechanistic work focused on the E. coli DnaK–GrpE system, and the functional context (Hsp70 chaperone; cochaperones DnaJ and GrpE; NBD+SBD architecture) matches the UniProt description. (maqtedar2026thenucleotideexchange pages 15-20, mayer2021thehsp70chaperonemachines pages 1-2)

2) Key concepts, definitions, and current understanding

2.1 Core molecular function: ATP-dependent Hsp70 chaperone

DnaK is an ATP-dependent molecular chaperone that binds short, degenerate peptide motifs in client proteins and uses an ATP-driven allosteric cycle to switch between low- and high-affinity client-binding states. (mayer2021thehsp70chaperonemachines pages 1-2, bhandari2015prokaryoticsystemsbiology pages 4-7)

Domain architecture (definitions): DnaK is composed of (i) an N-terminal nucleotide-binding domain (NBD), (ii) a conserved interdomain linker, and (iii) a C-terminal substrate-binding domain (SBD) that includes a β-sandwich peptide-binding pocket (SBDβ), an α-helical “lid” (SBDα), and a flexible/disordered C-terminal segment. (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)

2.2 Chaperone cycle and cochaperones (DnaJ/GrpE)

Nucleotide-coupled substrate binding: In the ATP-bound state, DnaK adopts a more open conformation with low substrate affinity and fast exchange, whereas the ADP-bound state favors high-affinity substrate capture (often described as lid-closed/trapped substrate). (bhandari2015prokaryoticsystemsbiology pages 4-7, melero2015modulationofthe pages 1-2)

Cochaperone roles:
- DnaJ (Hsp40/J-domain protein): stimulates DnaK ATPase activity and participates in substrate delivery/targeting. (bhandari2015prokaryoticsystemsbiology pages 4-7, bhandari2015prokaryoticsystemsbiology pages 7-9)
- GrpE (nucleotide exchange factor; NEF): accelerates ADP release from DnaK, promoting ATP rebinding and thereby enabling substrate release/turnover; GrpE also participates in regulating DnaK allostery. (bhandari2015prokaryoticsystemsbiology pages 4-7, rossi2024newinsightsinto pages 1-2)

Quantitative enzymology (representative): substrate alone can stimulate DnaK ATPase activity by ~2–10-fold, while DnaJ + substrate can synergistically enhance ATPase stimulation by >1000-fold in reported mechanistic summaries. (bhandari2015prokaryoticsystemsbiology pages 4-7)

2.3 Substrate specificity and proteome-wide scope

DnaK binds short hydrophobic motifs (commonly described as ~7-residue cores, frequently Leu-enriched and flanked by basic residues). Such motifs are common: one estimate reports an average frequency of ~1 potential DnaK site per 36 residues, implying that ~98% of E. coli proteins harbor at least one potential DnaK-binding segment. (bhandari2015prokaryoticsystemsbiology pages 4-7)

Proteome-scale computational analysis further supports broad surveillance: predicted DnaK- and DnaJ-binding motifs occur across nearly all proteins, with DnaJ sites predicted ~2× as often as DnaK sites and many predicted to overlap. (srinivasan2012molecularchaperonesdnak pages 1-2)

2.4 Cellular localization and biological processes/pathways

Localization: DnaK is primarily a cytoplasmic chaperone. In a large pull-down/MS interactome compilation, ~80% of identified DnaK interactors were cytoplasmic, while the remainder included membrane/periplasm-associated proteins. (bhandari2015prokaryoticsystemsbiology pages 7-9)

Biological processes: DnaK is a central hub in bacterial proteostasis, functioning in de novo folding, stress-denatured protein handling, and aggregate management (often in cooperation with other chaperones such as ClpB). (mayer2021thehsp70chaperonemachines pages 1-2, hoskins2025hsp90dnakand pages 1-2)

Heat-shock regulation pathway (RpoH/σ32): DnaK has a regulatory role in heat shock control circuits; in particular, deletion of dnaK causes pronounced stress phenotypes and commonly selects for suppressors in rpoH (σ32), consistent with DnaK being part of a feedback mechanism controlling heat shock transcriptional programs. (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)

Physiological importance: ΔdnaK strains show marked temperature-related growth defects (reported restricted growth in the range of ~20–35°C) and filamentation. (mayer2021thehsp70chaperonemachines pages 2-4)

3) Recent developments and latest research (prioritizing 2023–2024)

3.1 2024 structural/mechanistic update: DnaK–GrpE complex in E. coli

A major E. coli-specific advance is the 2024 Journal of Biological Chemistry paper: Rossi et al., “New insights into the structure and function of the complex between the Escherichia coli Hsp70, DnaK, and its nucleotide-exchange factor, GrpE” (publication date Jan 2024, https://doi.org/10.1016/j.jbc.2023.105574). The work synthesizes structural modeling/solution evidence to revise how GrpE opens the DnaK nucleotide-binding cleft, emphasizing movement/rotation of NBD subdomain IIB as part of the nucleotide exchange mechanism and reporting a GrpE thermosensor-relevant melting temperature (~48°C). (rossi2024newinsightsinto pages 1-2)

The paper notes that a previously used GrpE G122D mutation yields a weak complex and lacks functional NEF/refolding activity, motivating re-evaluation of mechanistic models based on that variant. (rossi2024newinsightsinto pages 1-2)

Image-supported mechanistic claim: structural overlays and models in the 2024 JBC paper depict subdomain IIB rotation (reported as 14° in an overlay context) and a model with a more open nucleotide-binding cleft upon GrpE binding. (rossi2024newinsightsinto media 7fa2413d)

3.2 2023 computational analysis of allosteric signaling (DnaK vs BiP)

A 2023 study used molecular dynamics and mutual information metrics to compare allosteric signaling features between E. coli DnaK and human BiP, aiming to identify residues contributing to conformational coupling between ligand-binding sites and cochaperone/substrate interactions. This supports ongoing mechanistic refinement of Hsp70-family allostery using simulation-based network approaches. (jiang2025mechanismsofassembly pages 23-24)

3.3 2024: infection-relevant stress roles of bacterial DnaK (enteric bacteria)

A 2024 PLOS Biology study (Apr 2024; https://doi.org/10.1371/journal.pbio.3002560) reported that Salmonella DnaK can promote survival under infection-relevant stress (cytoplasmic Mg2+ starvation) by reducing protein synthesis; the paper describes specific survival/protein-synthesis assay conditions and genetic requirements. While this is not E. coli K-12 directly, it highlights a potentially broader bacterial DnaK function linking proteostasis to translational control under host-like stress conditions. (chan2024chaperonehsp70helps pages 23-25)

4) Current applications and real-world implementations

4.1 DnaK as an experimental workhorse in protein folding/disaggregation assays

The DnaK/DnaJ/GrpE system is widely used as a reconstituted in vitro chaperone machine. For example, mechanistic work on DnaK functional tuning and cochaperone coupling uses denatured luciferase refolding/reactivation assays and peptide-binding assays to quantify effects of cochaperones and mutants. (rossi2024newinsightsinto pages 1-2, melero2015modulationofthe pages 1-2)

DnaK also participates in multi-chaperone systems; biochemical characterization of its collaboration with E. coli Hsp90 (Hsp90Ec) includes binding and activity synergy measurements, supporting DnaK’s role as a remodeling hub rather than an isolated foldase. (kravats2017interactionofe. pages 10-15)

4.2 Antimicrobial/anti-biofilm targeting concepts

DnaK is an explored antibacterial target, including via peptide antagonists and inhibitor screening concepts. A 2024 microbiology study on an SMR peptide reported dose-dependent inhibition of Staphylococcus aureus biofilm formation via targeting DnaK, with “significant inhibition” at 18 µM, 36 µM, and 72 µM (organism differs from E. coli, but the target concept is DnaK-directed anti-biofilm activity). (huang2024smrpeptideantagonizes pages 12-12)

5) Quantitative statistics and data relevant to functional annotation

A consolidated set of quantitative findings extracted from the evidence is provided below.

Topic	Key finding	Quantitative/stat	Source (with year, DOI URL)
Identity	Target verified as DnaK/Hsp70 from Escherichia coli K-12, UniProt P0A6Y8; canonical bacterial Hsp70 with DnaJ/GrpE cochaperone system (maqtedar2026thenucleotideexchange pages 15-20, mayer2021thehsp70chaperonemachines pages 1-2)	UniProt P0A6Y8	Rossi et al., 2024, JBC, https://doi.org/10.1016/j.jbc.2023.105574 (maqtedar2026thenucleotideexchange pages 15-20, rossi2024newinsightsinto pages 1-2)
Domain architecture	DnaK contains an N-terminal nucleotide-binding domain (NBD) linked to a C-terminal substrate-binding domain (SBD) with SBDβ, SBDα lid, and disordered C-tail; DnaJ targets/stimulates ATP hydrolysis and GrpE catalyzes nucleotide exchange (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2, hoskins2025hsp90dnakand pages 1-2)	NBD ~385 aa; SBD ~240 aa; SBDβ ~110 aa; SBDα ~100 aa; tail ~30 aa	Mayer, 2021, Front. Mol. Biosci., https://doi.org/10.3389/fmolb.2021.694012 (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)
ATPase/substrate cycle	ATP-bound DnaK is in a more open, low-affinity, fast-exchange state; ATP hydrolysis and ADP binding favor a closed, high-affinity substrate-trapping state; GrpE promotes ADP release/ATP rebinding, enabling substrate release (bhandari2015prokaryoticsystemsbiology pages 4-7, melero2015modulationofthe pages 1-2)	Substrate stimulates ATPase 2–10×; DnaJ + substrate >1000× synergistic stimulation	Bhandari & Houry, 2015, https://doi.org/10.1007/978-3-319-23603-2 (bhandari2015prokaryoticsystemsbiology pages 4-7); Melero et al., 2015, JBC, https://doi.org/10.1074/jbc.m114.623371 (melero2015modulationofthe pages 1-2)
GrpE mechanism / thermosensor	GrpE binds the DnaK NBD and opens the nucleotide-binding cleft by driving motion of subdomain IIB; GrpE also acts as a thermosensor because its coiled-coil is heat sensitive (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto pages 10-11)	Subdomain IIB rotation reported as 14° in prior structure overlay; GrpE Tm ~48°C	Rossi et al., 2024, JBC, https://doi.org/10.1016/j.jbc.2023.105574 (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto media 7fa2413d)
2024 DnaK–GrpE advance	2024 JBC study revised the E. coli DnaK–GrpE structural model, indicating a larger IIB rotation and more open nucleotide cleft than the older crystal model; supports direct GrpE-triggered allosteric signaling to DnaK domains (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto media 7fa2413d)	Larger-than-14° opening inferred; qualitative mechanistic revision	Rossi et al., 2024, JBC, https://doi.org/10.1016/j.jbc.2023.105574 (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto media 7fa2413d)
Proteome interaction scope	Large-scale pulldown/MS identified a broad E. coli DnaK interactome spanning many pathways and cellular compartments, though mainly cytoplasmic (bhandari2015prokaryoticsystemsbiology pages 7-9)	674 interactors; ~80% cytoplasmic	Bhandari & Houry, 2015, https://doi.org/10.1007/978-3-319-23603-2 (bhandari2015prokaryoticsystemsbiology pages 7-9)
Aggregation-linked clients	Upon DnaK/DnaJ depletion, many proteins aggregate; larger and thermolabile proteins are enriched among affected substrates (bhandari2015prokaryoticsystemsbiology pages 7-9)	~340 major aggregate spots; 94 identified by MS; ~72% thermolabile; enriched proteins often >60 kDa	Bhandari & Houry, 2015, https://doi.org/10.1007/978-3-319-23603-2 (bhandari2015prokaryoticsystemsbiology pages 7-9)
Substrate motif prevalence	DnaK recognizes short hydrophobic motifs, often Leu-enriched and flanked by basic residues; such motifs are widespread across the proteome (bhandari2015prokaryoticsystemsbiology pages 4-7)	Motif core ~7 aa; occurs ~1 per 36 aa on average; potential sites in ~98% of E. coli proteins	Bhandari & Houry, 2015, https://doi.org/10.1007/978-3-319-23603-2 (bhandari2015prokaryoticsystemsbiology pages 4-7)
DnaK:DnaJ binding-site coverage	Computational proteome analysis predicted that most E. coli proteins contain multiple overlapping DnaK and DnaJ sites, consistent with broad chaperone surveillance and stoichiometric tuning during refolding (srinivasan2012molecularchaperonesdnak pages 1-2)	Nearly every E. coli protein has multiple sites; DnaJ sites predicted ~2× as often as DnaK sites	Srinivasan et al., 2012, https://doi.org/10.1039/c2mb25145k (srinivasan2012molecularchaperonesdnak pages 1-2)
Network cooperation	DnaK directly collaborates with other chaperones such as Hsp90Ec in client remodeling; DnaK surface mutations can weaken this interaction (kravats2017interactionofe. pages 10-15)	Kd ~13 µM for DnaK–Hsp90Ec; mutant ~44 µM; Hsp90Ec can stimulate remodeling rate ~6×	Kravats et al., 2017, J. Mol. Biol., https://doi.org/10.1016/j.jmb.2016.12.014 (kravats2017interactionofe. pages 10-15)
Physiological importance	Loss of dnaK causes major proteostasis defects including temperature sensitivity and filamentation; suppressors often arise in rpoH/σ32 due to altered heat-shock regulation (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)	Growth restricted to ~20–35°C in ΔdnaK strains	Mayer, 2021, Front. Mol. Biosci., https://doi.org/10.3389/fmolb.2021.694012 (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)

Table: This table condenses verified identity, mechanism, quantitative findings, and recent structural advances for E. coli K-12 DnaK/Hsp70. It is useful as a citation-ready snapshot for the final research report.

Key quantitative highlights include:
- Interactome scale: 674 DnaK interactors reported in a pull-down/MS compilation, with ~80% cytoplasmic. (bhandari2015prokaryoticsystemsbiology pages 7-9)
- Aggregation under chaperone depletion: ~340 aggregate “spots” after DnaK/DnaJ depletion; 94 protein IDs; ~72% thermolabile. (bhandari2015prokaryoticsystemsbiology pages 7-9)
- Substrate motif prevalence: ~7-residue hydrophobic core; ~1 per 36 residues; ~98% proteins predicted to contain at least one potential site (one estimate). (bhandari2015prokaryoticsystemsbiology pages 4-7)
- Cochaperone-coupled ATPase stimulation: substrate alone ~2–10×; DnaJ + substrate >1000×. (bhandari2015prokaryoticsystemsbiology pages 4-7)
- GrpE thermosensor parameter: GrpE melting temperature ~48°C. (rossi2024newinsightsinto pages 1-2)
- NBD motion in nucleotide exchange: subdomain IIB rotation reported as 14° in an overlay context in the 2024 structural analysis. (rossi2024newinsightsinto media 7fa2413d)
- Network coupling to Hsp90Ec: DnaK–Hsp90Ec affinity Kd ~13 µM (mutant ~44 µM) and functional synergy in remodeling/refolding assays. (kravats2017interactionofe. pages 10-15)

6) Expert synthesis and interpretation (authoritative analysis grounded in evidence)

Primary molecular role: The collected evidence supports DnaK as a central ATP-driven chaperone that binds exposed hydrophobic segments and—through DnaJ-accelerated ATP hydrolysis and GrpE-driven nucleotide exchange—controls client binding lifetimes and folding trajectories. The large magnitude of cochaperone-dependent stimulation (>1000× with DnaJ+substrate in one summary) emphasizes that DnaK’s physiological behavior is primarily a cochaperone-programmed machine, not a standalone ATPase. (bhandari2015prokaryoticsystemsbiology pages 4-7)
System-level role: Proteome-wide motif predictions and interactome/aggregation datasets support the interpretation of DnaK as a global proteostasis hub whose client set is broad enough that impairing DnaK/DnaJ reveals widespread aggregation and stress sensitivity. (bhandari2015prokaryoticsystemsbiology pages 7-9, srinivasan2012molecularchaperonesdnak pages 1-2)
Regulatory coupling: The repeated observation that ΔdnaK strains acquire suppressors in rpoH/σ32 implies that DnaK activity is integrated into feedback control of heat-shock gene expression; this provides a mechanistic explanation for why perturbation of DnaK can produce strong pleiotropic phenotypes (filamentation; temperature sensitivity) that are downstream of transcriptional imbalance and proteostasis collapse. (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)
What is new in 2024: The 2024 JBC work strengthens the mechanistic linkage between GrpE binding and NBD structural remodeling (subdomain IIB movement opening the nucleotide cleft), while embedding this in a thermosensing framework (GrpE coiled-coil stability around ~48°C). This provides a more structurally explicit basis for nucleotide exchange and suggests routes by which GrpE binding can propagate allosteric signals beyond the immediate nucleotide pocket. (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto media 7fa2413d)

7) Limitations of the retrieved evidence

Some 2023–2024 application areas requested (e.g., E. coli K-12-specific clinical/industrial implementations; comprehensive recent antibacterial small-molecule pipelines directly validated on E. coli DnaK; phage-specific DnaK interactions in E. coli) were not fully represented in the retrieved full-text corpus. Where applications were discussed, they were sometimes present only as citation lists rather than primary quantitative results in the accessible excerpts. (huang2024smrpeptideantagonizes pages 12-12, benedetti2024bacterialdnakreduces pages 14-15)

8) Key references (with dates and URLs)

Mayer MP. Jun 2021. “The Hsp70-Chaperone Machines in Bacteria.” Frontiers in Molecular Biosciences. https://doi.org/10.3389/fmolb.2021.694012 (mayer2021thehsp70chaperonemachines pages 2-4, mayer2021thehsp70chaperonemachines pages 1-2)
Rossi M-A et al. Jan 2024. “New insights into the structure and function of the complex between the E. coli Hsp70, DnaK, and its nucleotide-exchange factor, GrpE.” Journal of Biological Chemistry. https://doi.org/10.1016/j.jbc.2023.105574 (rossi2024newinsightsinto pages 1-2, rossi2024newinsightsinto media 7fa2413d)
Bhandari V, Houry WA. Jan 2015. “Prokaryotic Systems Biology.” https://doi.org/10.1007/978-3-319-23603-2 (bhandari2015prokaryoticsystemsbiology pages 7-9, bhandari2015prokaryoticsystemsbiology pages 4-7)
Kravats AN et al. Mar 2017. “Interaction of E. coli Hsp90 with DnaK…” Journal of Molecular Biology. https://doi.org/10.1016/j.jmb.2016.12.014 (kravats2017interactionofe. pages 10-15)
Srinivasan SR et al. Jul 2012. “Molecular chaperones DnaK and DnaJ share predicted binding sites…” Molecular BioSystems. https://doi.org/10.1039/c2mb25145k (srinivasan2012molecularchaperonesdnak pages 1-2)
Chan C, Groisman EA. Apr 2024. “Chaperone Hsp70 helps Salmonella survive infection-relevant stress…” PLOS Biology. https://doi.org/10.1371/journal.pbio.3002560 (chan2024chaperonehsp70helps pages 23-25)
Huang M-B et al. Feb 2024. “SMR peptide antagonizes Staphylococcus aureus biofilm formation.” Microbiology Spectrum. https://doi.org/10.1128/spectrum.02583-23 (huang2024smrpeptideantagonizes pages 12-12)

References

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(mayer2021thehsp70chaperonemachines pages 1-2): Matthias P. Mayer. The hsp70-chaperone machines in bacteria. Frontiers in Molecular Biosciences, Jun 2021. URL: https://doi.org/10.3389/fmolb.2021.694012, doi:10.3389/fmolb.2021.694012. This article has 93 citations.
(bhandari2015prokaryoticsystemsbiology pages 4-7): V Bhandari and WA Houry. Prokaryotic systems biology. ArXiv, Jan 2015. URL: https://doi.org/10.1007/978-3-319-23603-2, doi:10.1007/978-3-319-23603-2. This article has 44 citations.
(mayer2021thehsp70chaperonemachines pages 2-4): Matthias P. Mayer. The hsp70-chaperone machines in bacteria. Frontiers in Molecular Biosciences, Jun 2021. URL: https://doi.org/10.3389/fmolb.2021.694012, doi:10.3389/fmolb.2021.694012. This article has 93 citations.
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(rossi2024newinsightsinto pages 1-2): Maria-Agustina Rossi, Alexandra K. Pozhidaeva, Eugenia M. Clerico, Constantine Petridis, and Lila M. Gierasch. New insights into the structure and function of the complex between the escherichia coli hsp70, dnak, and its nucleotide-exchange factor, grpe. Journal of Biological Chemistry, 300:105574, Jan 2024. URL: https://doi.org/10.1016/j.jbc.2023.105574, doi:10.1016/j.jbc.2023.105574. This article has 8 citations and is from a domain leading peer-reviewed journal.
(srinivasan2012molecularchaperonesdnak pages 1-2): Sharan R. Srinivasan, Anne T. Gillies, Lyra Chang, Andrea D. Thompson, and Jason E. Gestwicki. Molecular chaperones dnak and dnaj share predicted binding sites on most proteins in the e. coli proteome. Molecular bioSystems, 8 9:2323-33, Jul 2012. URL: https://doi.org/10.1039/c2mb25145k, doi:10.1039/c2mb25145k. This article has 47 citations and is from a peer-reviewed journal.
(hoskins2025hsp90dnakand pages 1-2): Joel R. Hoskins, Anushka C. Wickramaratne, Connor P. Jewell, Lisa M. Jenkins, and Sue Wickner. Hsp90, dnak, and clpb collaborate in protein reactivation. Proceedings of the National Academy of Sciences of the United States of America, Jan 2025. URL: https://doi.org/10.1073/pnas.2422640122, doi:10.1073/pnas.2422640122. This article has 3 citations and is from a highest quality peer-reviewed journal.
(rossi2024newinsightsinto media 7fa2413d): Maria-Agustina Rossi, Alexandra K. Pozhidaeva, Eugenia M. Clerico, Constantine Petridis, and Lila M. Gierasch. New insights into the structure and function of the complex between the escherichia coli hsp70, dnak, and its nucleotide-exchange factor, grpe. Journal of Biological Chemistry, 300:105574, Jan 2024. URL: https://doi.org/10.1016/j.jbc.2023.105574, doi:10.1016/j.jbc.2023.105574. This article has 8 citations and is from a domain leading peer-reviewed journal.
(jiang2025mechanismsofassembly pages 23-24): Yajun Jiang, Ziad Ibrahim, Youlin Xia, Mary Clay, Alexander Myasnikov, Kalyan Immadisetty, Zhilian Xia, Liang Tang, Paolo Rossi, Pritha Ganguly, Jiangshu Liu, Darcie Miller, Meixia Che, Santiago M. Palacios, Günter Kramer, Bernd Bukau, and Charalampos G. Kalodimos. Mechanisms of assembly and function of the hsp70-hsp40 chaperone machinery. Molecular Cell, 85(21):4032-4046.e7, Nov 2025. URL: https://doi.org/10.1016/j.molcel.2025.09.023, doi:10.1016/j.molcel.2025.09.023. This article has 1 citations and is from a highest quality peer-reviewed journal.
(chan2024chaperonehsp70helps pages 23-25): Carissa Chan and Eduardo A. Groisman. Chaperone hsp70 helps salmonella survive infection-relevant stress by reducing protein synthesis. PLOS Biology, 22:e3002560, Apr 2024. URL: https://doi.org/10.1371/journal.pbio.3002560, doi:10.1371/journal.pbio.3002560. This article has 12 citations and is from a highest quality peer-reviewed journal.
(kravats2017interactionofe. pages 10-15): Andrea N. Kravats, Shannon M. Doyle, Joel R. Hoskins, Olivier Genest, Erin Doody, and Sue Wickner. Interaction of e. coli hsp90 with dnak involves the dnaj binding region of dnak. Journal of Molecular Biology, 429(6):858-872, Mar 2017. URL: https://doi.org/10.1016/j.jmb.2016.12.014, doi:10.1016/j.jmb.2016.12.014. This article has 55 citations and is from a domain leading peer-reviewed journal.
(huang2024smrpeptideantagonizes pages 12-12): Ming-Bo Huang, Dara Brena, Jennifer Y. Wu, Martin Shelton, and Vincent C. Bond. Smr peptide antagonizes staphylococcus aureus biofilm formation. Feb 2024. URL: https://doi.org/10.1128/spectrum.02583-23, doi:10.1128/spectrum.02583-23. This article has 7 citations and is from a domain leading peer-reviewed journal.
(rossi2024newinsightsinto pages 10-11): Maria-Agustina Rossi, Alexandra K. Pozhidaeva, Eugenia M. Clerico, Constantine Petridis, and Lila M. Gierasch. New insights into the structure and function of the complex between the escherichia coli hsp70, dnak, and its nucleotide-exchange factor, grpe. Journal of Biological Chemistry, 300:105574, Jan 2024. URL: https://doi.org/10.1016/j.jbc.2023.105574, doi:10.1016/j.jbc.2023.105574. This article has 8 citations and is from a domain leading peer-reviewed journal.
(benedetti2024bacterialdnakreduces pages 14-15): Francesca Benedetti, Emmanuel F. Mongodin, Jonathan H. Badger, Arshi Munawwar, Ashley Cellini, Weirong Yuan, Giovannino Silvestri, Carl N. Kraus, Simone Marini, Chozha V. Rathinam, Marco Salemi, Hervé Tettelin, Robert C. Gallo, and Davide Zella. Bacterial dnak reduces the activity of anti-cancer drugs cisplatin and 5fu. Journal of Translational Medicine, Mar 2024. URL: https://doi.org/10.1186/s12967-024-05078-x, doi:10.1186/s12967-024-05078-x. This article has 6 citations and is from a peer-reviewed journal.

Citations

bhandari2015prokaryoticsystemsbiology pages 4-7
srinivasan2012molecularchaperonesdnak pages 1-2
bhandari2015prokaryoticsystemsbiology pages 7-9
rossi2024newinsightsinto pages 1-2
jiang2025mechanismsofassembly pages 23-24
huang2024smrpeptideantagonizes pages 12-12
melero2015modulationofthe pages 1-2
maqtedar2026thenucleotideexchange pages 15-20
rossi2024newinsightsinto pages 10-11
benedetti2024bacterialdnakreduces pages 14-15
https://doi.org/10.1016/j.jbc.2023.105574
https://doi.org/10.1371/journal.pbio.3002560
https://doi.org/10.3389/fmolb.2021.694012
https://doi.org/10.1007/978-3-319-23603-2
https://doi.org/10.1074/jbc.m114.623371
https://doi.org/10.1039/c2mb25145k
https://doi.org/10.1016/j.jmb.2016.12.014
https://doi.org/10.1128/spectrum.02583-23
https://doi.org/10.1101/2025.10.21.683677,
https://doi.org/10.3389/fmolb.2021.694012,
https://doi.org/10.1007/978-3-319-23603-2,
https://doi.org/10.1074/jbc.m114.623371,
https://doi.org/10.1016/j.jbc.2023.105574,
https://doi.org/10.1039/c2mb25145k,
https://doi.org/10.1073/pnas.2422640122,
https://doi.org/10.1016/j.molcel.2025.09.023,
https://doi.org/10.1371/journal.pbio.3002560,
https://doi.org/10.1016/j.jmb.2016.12.014,
https://doi.org/10.1128/spectrum.02583-23,
https://doi.org/10.1186/s12967-024-05078-x,

Bioreason Rl Review

(DnaK-bioreason-rl-review.md)

BioReason-Pro RL Review: DnaK (E. coli)

Source: DnaK-deep-research-bioreason-rl.md

Correctness: 4/5
Completeness: 3/5

Functional Summary Review

The BioReason functional summary describes DnaK as:

A cytoplasmic ATP-dependent heat-shock chaperone that cycles between nucleotide-bound states to capture and release exposed hydrophobic segments on non-native polypeptides. By coupling an ATPase engine to a peptide-binding clamp, it stabilizes misfolded intermediates, prevents aggregation, and promotes productive refolding during stress and normal proteostasis. In bacteria, it operates with cognate cochaperones to triage clients toward recovery or degradation, thereby preserving proteome integrity in the cytoplasm.

This is a solid summary that correctly captures the core molecular mechanism of DnaK. The domain architecture (N-terminal ATPase NBD, C-terminal peptide-binding SBD with lid) is well described in the thinking trace. The summary accurately identifies:
- ATP-dependent conformational cycling
- Hydrophobic peptide recognition
- Refolding promotion and aggregation prevention
- Co-chaperone cooperation (DnaJ, GrpE mentioned in trace)
- Cytoplasmic localization

However, notable omissions reduce completeness:
- No mention of the holdase function (ATP-independent aggregation prevention, PMID:2203539)
- No mention of the regulatory role in the heat shock response via sigma32/RpoH inactivation, which is a well-established second core function
- No mention of cooperation with trigger factor for nascent polypeptide chaperoning
- No mention of cooperation with ClpB for disaggregation
- No mention of the role in DNA replication (phage lambda, chromosomal via DnaA)

The functional summary describes DnaK as a chaperone only, missing its moonlighting regulatory functions.

Comparison with interpro2go:

The curated review's interpro2go annotations include protein folding (correct, from IPR012725), ATP hydrolysis activity (correct, from IPR013126), and unfolded protein binding (correct but noted as overly simplistic). BioReason recapitulates these interpro2go-level annotations faithfully but does not add significant biological insight beyond what the domain architecture predicts. The narrative is essentially a well-written expansion of what interpro2go already provides. The GO term predictions also include transport-related terms (protein transmembrane transport, intracellular protein transport) which are not the core function of DnaK.

Notes on thinking trace

The trace provides clean mechanistic reasoning from domain architecture to function. The mention of "trigger factor or ribosome-associated modules" as potential partners is appropriate. The GrpE nucleotide exchange factor is correctly identified. Overall the reasoning is accurate but conservative, staying within the chaperone paradigm without venturing into the well-documented regulatory functions.

📄 View Raw YAML

id: P0A6Y8
gene_symbol: DnaK
product_type: PROTEIN
status: IN_PROGRESS
taxon:
  id: NCBITaxon:83333
  label: Escherichia coli (strain K12)
description: 'DnaK is the E. coli HSP70 homolog and the canonical bacterial chaperone.
  It is an ATP-dependent foldase that works in concert with its J-domain co-chaperone
  DnaJ (Hsp40) and nucleotide exchange factor GrpE to assist de novo protein folding
  and repair heat-damaged proteins. DnaK undergoes ATP-driven conformational cycles:
  ATP-bound DnaK has an open substrate-binding domain with fast on/off rates; ATP
  hydrolysis (stimulated by DnaJ and substrate) closes the lid and stabilizes substrate
  binding; GrpE-catalyzed ADP release and ATP rebinding triggers substrate release
  for folding. Multiple rounds of this cycle are required for efficient folding of
  many substrates (PMID:7937953). DnaK also functions as a holdase under some conditions,
  protecting proteins from aggregation in an ATP-independent manner (PMID:2203539).
  It cooperates with trigger factor in chaperoning nascent polypeptides (PMID:10380927),
  and collaborates with ClpB (Hsp100) in disaggregation of protein aggregates. DnaK
  also plays a regulatory role by binding and inactivating the heat shock transcription
  factor sigma32 (RpoH) through chaperone-mediated feedback (PMID:8599944). Additionally,
  DnaK is essential for phage lambda DNA replication and participates in chromosomal
  DNA replication via interaction with DnaA.'
existing_annotations:
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: DnaK has intrinsic ATPase activity that is central to its chaperone cycle.
      The ATP hydrolysis rate is stimulated by substrates and DnaJ (PMID:7776367).
      IBA annotation is well-supported phylogenetically across the HSP70 family and
      experimentally validated for DnaK.
    action: ACCEPT
    reason: Core enzymatic activity of DnaK. ATP hydrolysis drives the conformational
      cycle essential for chaperone function. Well-documented experimentally (PMID:7776367,
      PMID:7937953).
    supported_by:
    - reference_id: PMID:7776367
      supporting_text: DnaK ATPase was stimulated by substrates (ninefold) and DnaJ
        (13-fold) through stimulation of the rate limiting step, gamma-phosphate cleavage
    - reference_id: PMID:7937953
      supporting_text: upon interaction with luciferase-DnaJ, DnaK hydrolyzes its
        bound ATP, resulting in the formation of a stable luciferase-DnaK-DnaJ complex
- term:
    id: GO:0031072
    label: heat shock protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: DnaK directly binds its co-chaperones DnaJ (Hsp40) and GrpE, as well
      as HtpG (Hsp90) and ClpB (Hsp100). The IBA annotation reflects conserved interactions
      across the HSP70 family. Multiple experimental studies confirm these interactions
      in E. coli (PMID:9103205, PMID:2522091, PMID:21525416).
    action: ACCEPT
    reason: DnaK forms functional complexes with multiple heat shock proteins including
      DnaJ, GrpE, HtpG, and ClpB. This is a well-established feature of the HSP70
      chaperone system.
    supported_by:
    - reference_id: PMID:9103205
      supporting_text: Crystal structure of the nucleotide exchange factor GrpE bound
        to the ATPase domain of the molecular chaperone DnaK
    - reference_id: PMID:21525416
      supporting_text: Results indicate that E. coli Hsp90 and DnaK interact in vivo
        and in vitro
- term:
    id: GO:0044183
    label: protein folding chaperone
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: DnaK is the canonical bacterial protein folding chaperone (foldase).
      It assists protein folding through iterative ATP-driven binding-and-release
      cycles (PMID:7937953). The IBA annotation is well-supported and represents a
      core function of the HSP70 family.
    action: ACCEPT
    reason: Core molecular function of DnaK. The IBA captures the foldase activity
      at the correct level of specificity. DnaK has both GO:0044183 (general foldase)
      and GO:0140662 (ATP-dependent foldase) annotations; both are appropriate with
      GO:0140662 being more specific.
    supported_by:
    - reference_id: PMID:7937953
      supporting_text: Several rounds of ATP-dependent interaction with DnaK and DnaJ
        are required for fully efficient folding
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: DnaK is predominantly a cytosolic protein. This is supported by multiple
      proteomic studies (PMID:15911532, PMID:18304323) and IBA phylogenetic inference.
    action: ACCEPT
    reason: Well-established localization for DnaK, confirmed by both IDA and IBA
      evidence.
- term:
    id: GO:0042026
    label: protein refolding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: DnaK is directly involved in refolding heat-damaged proteins. Schroder
      et al. (1993) showed that DnaK, DnaJ, and GrpE are essential for reactivation
      of heat-inactivated luciferase both in vivo and in vitro (PMID:7900997). Skowyra
      et al. (1990) demonstrated DnaK reactivates heat-inactivated RNA polymerase
      in an ATP-dependent manner (PMID:2203539).
    action: ACCEPT
    reason: Core biological process for DnaK. Protein refolding (repair of heat-damaged
      proteins) is one of the best-characterized functions of the DnaK/DnaJ/GrpE system.
    supported_by:
    - reference_id: PMID:7900997
      supporting_text: DnaK, DnaJ and GrpE did not prevent luciferase inactivation,
        but were essential for its reactivation
    - reference_id: PMID:2203539
      supporting_text: heat-inactivated and aggregated RNA polymerase is both disaggregated
        and reactivated following simultaneous incubation with DnaK protein and hydrolyzable
        ATP
- term:
    id: GO:0045892
    label: negative regulation of DNA-templated transcription
  evidence_type: IEA
  original_reference_id: GO_REF:0000108
  review:
    summary: This IEA annotation is inferred from GO:0016989 (sigma factor antagonist
      activity) via logical inference. DnaK binds and inactivates sigma32, which represses
      heat shock gene transcription (PMID:8599944). The inference is sound since antagonizing
      sigma32 leads to negative regulation of sigma32-dependent transcription.
    action: ACCEPT
    reason: Logically sound inference from the experimentally validated sigma factor
      antagonist activity (GO:0016989). DnaK-mediated sequestration of sigma32 represses
      heat shock gene transcription.
    supported_by:
    - reference_id: PMID:8599944
      supporting_text: DnaK and DnaJ cooperatively inhibit sigma32 activity in heat
        shock gene transcription
- term:
    id: GO:0000166
    label: nucleotide binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: IEA annotation from UniProt keyword mapping. DnaK binds both ATP and
      ADP, which is well-established experimentally (PMID:7776367, PMID:19439666).
      This is a broader parent of the more specific ATP binding annotation.
    action: ACCEPT
    reason: Correct but very general. Subsumed by more specific ATP binding (GO:0005524)
      and ADP binding (GO:0043531) annotations which are experimentally validated.
      Acceptable as an IEA annotation.
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for ATP binding, which is also supported by direct IDA
      evidence (PMID:9103205, PMID:7776367). DnaK has a well-characterized N-terminal
      ATPase domain.
    action: ACCEPT
    reason: Correct annotation. ATP binding is a core feature of DnaK's N-terminal
      nucleotide-binding domain. Redundant with IDA-supported annotations but acceptable.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: IEA annotation from UniProt subcellular location mapping. DnaK is predominantly
      cytoplasmic, confirmed by HDA (PMID:16858726) and IDA (PMID:15911532, PMID:18304323)
      evidence as well.
    action: ACCEPT
    reason: Correct localization. Broader than cytosol (GO:0005829) but acceptable
      as IEA.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: IEA annotation from UniProt subcellular location. UniProt lists DnaK
      as a peripheral inner membrane protein (PMID:16079137). DnaK has also been found
      associated with membrane fractions (PMID:16858726 HDA). This is a secondary
      localization.
    action: KEEP_AS_NON_CORE
    reason: DnaK is primarily cytosolic but has been detected at the cell inner membrane
      as a peripheral protein. This is not a core localization but is supported by
      UniProt annotations citing PMID:16079137.
- term:
    id: GO:0006260
    label: DNA replication
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: IEA annotation from UniProt keyword mapping (KW-0235 DNA replication).
      UniProt describes DnaK as essential for phage lambda DNA replication and involved
      in chromosomal DNA replication through interaction with DnaA. This reflects
      a genuine but non-core function.
    action: KEEP_AS_NON_CORE
    reason: DnaK's role in DNA replication is well-documented for phage lambda (releasing
      lambda O and P from the preprimosomal complex) and proposed for chromosomal
      replication via DnaA interaction. However, this is not DnaK's primary evolved
      function -- it reflects chaperone activity applied to replication machinery,
      not a direct replication function.
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro (IPR012725, Chaperone_DnaK). DnaK is a core
      protein folding chaperone. This BP annotation is correct and also supported
      by IDA evidence (PMID:9103205).
    action: ACCEPT
    reason: Protein folding is the core biological process in which DnaK participates.
      This IEA is consistent with the extensive experimental evidence.
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro (IPR013126, Hsp_70_fam). Duplicates the
      IBA annotation for the same term. DnaK has well-characterized intrinsic ATPase
      activity.
    action: ACCEPT
    reason: Correct. Duplicate of the IBA annotation but from a different evidence
      source. ATP hydrolysis is central to DnaK function.
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation from InterPro (IPR012725). GO:0051082 is proposed for
      obsoletion (go-ontology#30962). DnaK does bind unfolded proteins, but this binding
      is in the context of its foldase activity, not as a passive binder. The function
      is better captured by GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent
      protein folding chaperone), both of which DnaK already has.
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion. DnaK's binding of unfolded proteins
      is mechanistically part of its ATP-dependent foldase cycle, not passive binding.
      The correct MF is GO:0044183 or its child GO:0140662. DnaK can also function
      as a holdase in some contexts (PMID:2203539, ATP-independent protection from
      aggregation), but the holdase NTR has not yet been created.
    proposed_replacement_terms:
    - id: GO:0044183
      label: protein folding chaperone
    supported_by:
    - reference_id: PMID:7937953
      supporting_text: DnaK, the Hsp70 protein of Escherichia coli, is regulated by
        the chaperone protein DnaJ and the cofactor GrpE...we have analyzed a model
        reaction in which DnaK, DnaJ, and GrpE mediate the folding of denatured firefly
        luciferase
- term:
    id: GO:0051087
    label: protein-folding chaperone binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: IEA annotation from ARBA machine learning. DnaK binds multiple chaperones
      including DnaJ, GrpE, HtpG, and ClpB. This is also supported by IPI evidence
      (PMID:9103205, PMID:21525416).
    action: ACCEPT
    reason: Correct. DnaK physically interacts with multiple protein-folding chaperones
      as part of its functional cycle.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:10521435
  review:
    summary: IPI with DnaJ (P08622). Suh et al. (1999) characterized structural features
      required for DnaK-DnaJ interaction. This is a functionally meaningful chaperone-co-chaperone
      interaction central to DnaK function.
    action: MODIFY
    reason: The DnaK-DnaJ interaction is a core co-chaperone interaction, not generic
      protein binding. Better captured by GO:0031072 (heat shock protein binding)
      or GO:0051087 (protein-folding chaperone binding), which DnaK already has.
    proposed_replacement_terms:
    - id: GO:0051087
      label: protein-folding chaperone binding
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:15690043
  review:
    summary: IPI from a large-scale interaction study (Butland et al. 2005) detecting
      DnaK interactions with multiple E. coli proteins including DnaJ (P08622), GrpE
      (P09372), RpoH (P0AGB3), and many others. As a chaperone, DnaK is expected to
      interact with a wide range of cellular proteins. GO:0005515 is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: Large-scale protein interaction study. DnaK as a chaperone interacts with
      many cellular proteins; generic protein binding does not capture the mechanistic
      basis. The specific co-chaperone interactions (DnaJ, GrpE) are better annotated
      with GO:0051087.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16139413
  review:
    summary: IPI with Rne/RNase E (P21513). DnaK was found associated with the RNA
      degradosome complex. This likely reflects a chaperone-substrate interaction
      rather than a stable functional complex.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK association with the RNA degradosome is likely a chaperone-substrate
      interaction. Generic protein binding is uninformative for a promiscuous chaperone.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16606699
  review:
    summary: IPI from large-scale protein-protein interaction study (Arifuzzaman et
      al. 2006). DnaK interactions with GrpE, HtpG, RpoH, CbpA and others detected.
    action: MARK_AS_OVER_ANNOTATED
    reason: Large-scale interaction screen. DnaK is a chaperone with many interactors.
      GO:0005515 is uninformative. Specific functionally meaningful interactions are
      already captured by more specific terms.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16858726
  review:
    summary: IPI from complexomic study (Maddalo et al. 2006) detecting DnaK interactions
      with GrpE (P09372) and ClpB (P63284) by 2D blue native/SDS-PAGE.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK-GrpE and DnaK-ClpB interactions are well-known chaperone system interactions,
      better described by GO:0031072 or GO:0051087 than generic protein binding.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17357109
  review:
    summary: IPI with human HLA-DR molecules (P04233, A0A0G4PYZ0). This is a cross-species
      (xenologous) interaction where E. coli DnaK binds human MHC class II molecules.
      This is an in vitro finding relevant to immunology but not to DnaK's native
      cellular function.
    action: KEEP_AS_NON_CORE
    reason: Xenologous interaction with human HLA-DR. While demonstrating peptide-binding
      capacity of DnaK, this does not represent a native E. coli function.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17968012
  review:
    summary: IPI with RpoH/sigma32 (P0AGB3). Guisbert et al. (2008) analyzed sigma32
      mutants defective in chaperone-mediated feedback control. DnaK binding to sigma32
      is a central regulatory mechanism of the heat shock response.
    action: MODIFY
    reason: DnaK-sigma32 interaction is a functionally important regulatory interaction,
      better captured by GO:0016989 (sigma factor antagonist activity) which DnaK
      already has. GO:0005515 is uninformative.
    proposed_replacement_terms:
    - id: GO:0016989
      label: sigma factor antagonist activity
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18394994
  review:
    summary: IPI with DnaJ (P08622). Lin et al. (2008) studied chaperonin-assisted
      folding and DnaK-DnaJ cooperation. Functionally meaningful co-chaperone interaction.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK-DnaJ interaction is already captured by GO:0051087 (protein-folding
      chaperone binding). Generic protein binding is uninformative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19439666
  review:
    summary: IPI with DnaJ (P08622). Bertelsen et al. (2009) determined the solution
      structure of full-length DnaK complexed with ADP and substrate peptide. Important
      structural study showing domain dynamics.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK-DnaJ interaction already captured by more specific terms. This study's
      main contribution is structural understanding of the DnaK-ADP-substrate complex.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19698713
  review:
    summary: IPI with ClpB (P63284). Winkler et al. (2009) showed DnaK mediates association
      of ClpB to protein aggregates, forming a bichaperone network at aggregate surfaces.
      This is a functionally important disaggregation-related interaction.
    action: MODIFY
    reason: DnaK-ClpB interaction is a functionally meaningful chaperone-chaperone
      interaction for protein disaggregation, better captured by GO:0031072 (heat
      shock protein binding).
    proposed_replacement_terms:
    - id: GO:0031072
      label: heat shock protein binding
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21474779
  review:
    summary: IPI with ClpB (P63284). Zietkiewicz et al. (2011) studied species-specific
      collaboration of Hsp70 and Hsp100 in thermotolerance and protein disaggregation.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK-ClpB interaction for disaggregation is already captured by more specific
      terms. GO:0005515 is uninformative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:22065753
  review:
    summary: IPI with DnaJ (P08622). Ahmad et al. (2011) characterized the dynamic
      interface of the Hsp70/DnaJ cochaperone complex. Important structural study
      of co-chaperone interaction.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK-DnaJ interaction is a well-characterized co-chaperone interaction
      already annotated with GO:0051087. GO:0005515 adds nothing informative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:23160352
  review:
    summary: IPI with ClpB (P63284). Seyffer et al. (2012) showed that Hsp70 (DnaK)
      proteins bind to Hsp100 regulatory M domains to activate AAA+ disaggregase activity
      at aggregate surfaces.
    action: MODIFY
    reason: Functionally important DnaK-ClpB interaction for disaggregation activation.
      Better captured by GO:0031072 (heat shock protein binding).
    proposed_replacement_terms:
    - id: GO:0031072
      label: heat shock protein binding
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:24561554
  review:
    summary: IPI from binary protein-protein interaction landscape study (Rajagopala
      et al. 2014). Large-scale Y2H screen detecting DnaK interactions with HtpG (P0A6Z3)
      and CbpA (P36659).
    action: MARK_AS_OVER_ANNOTATED
    reason: Large-scale interaction screen. DnaK-HtpG and DnaK-CbpA are known chaperone
      interactions better captured by specific terms. GO:0005515 is uninformative.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:26545493
  review:
    summary: IPI with RpoH/sigma32 (P0AGB3). Masser et al. (2015) studied the GroEL-to-DnaK
      chaperone network behind sigma32 stability modulation. The DnaK-sigma32 interaction
      is a key regulatory mechanism.
    action: MODIFY
    reason: DnaK-sigma32 interaction for heat shock regulation is better captured
      by GO:0016989 (sigma factor antagonist activity).
    proposed_replacement_terms:
    - id: GO:0016989
      label: sigma factor antagonist activity
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:9103205
  review:
    summary: IPI with GrpE (P09372) from the crystal structure study of GrpE bound
      to the DnaK ATPase domain (Harrison et al. 1997). A dimer of GrpE binds asymmetrically
      to a single DnaK molecule.
    action: MODIFY
    reason: DnaK-GrpE is a core co-chaperone interaction essential for the DnaK functional
      cycle. Better captured by GO:0051087 (protein-folding chaperone binding).
    proposed_replacement_terms:
    - id: GO:0051087
      label: protein-folding chaperone binding
    supported_by:
    - reference_id: PMID:9103205
      supporting_text: A dimer of GrpE binds asymmetrically to a single molecule of
        DnaK
- term:
    id: GO:0009408
    label: response to heat
  evidence_type: IDA
  original_reference_id: PMID:7023474
  review:
    summary: Neidhardt and VanBogelen (1981) identified DnaK as a positive regulatory
      gene for temperature-controlled proteins. DnaK is one of the most highly induced
      heat shock proteins in E. coli.
    action: ACCEPT
    reason: DnaK (Hsp70) is a major heat shock protein that is strongly induced upon
      heat stress. Response to heat is a core biological process for this gene.
- term:
    id: GO:0009408
    label: response to heat
  evidence_type: IDA
  original_reference_id: PMID:7900997
  review:
    summary: Schroder et al. (1993) demonstrated that DnaK, DnaJ, and GrpE form a
      chaperone machinery capable of repairing heat-induced protein damage. DnaK is
      essential for reactivation of heat-inactivated luciferase.
    action: ACCEPT
    reason: Direct demonstration of DnaK function in the heat stress response, specifically
      repairing heat-damaged proteins.
    supported_by:
    - reference_id: PMID:7900997
      supporting_text: DnaK, DnaJ and GrpE did not prevent luciferase inactivation,
        but were essential for its reactivation
- term:
    id: GO:0009408
    label: response to heat
  evidence_type: IEP
  original_reference_id: PMID:8349564
  review:
    summary: Chuang and Blattner (1993) characterized heat shock genes in E. coli
      and showed DnaK has expression kinetics typical of major heat shock proteins.
      IEP (expression pattern) evidence.
    action: ACCEPT
    reason: DnaK is among the most well-characterized heat shock proteins. Its heat-induced
      expression pattern is consistent with its role in heat stress response.
    supported_by:
    - reference_id: PMID:8349564
      supporting_text: In vivo expression kinetics of seven of eight examined new
        proteins were found to be similar to those of the four most studied heat shock
        proteins, DnaK, DnaJ, GroEL (MopA), and GroES (MopB)
- term:
    id: GO:0034620
    label: cellular response to unfolded protein
  evidence_type: IDA
  original_reference_id: PMID:2203539
  review:
    summary: Skowyra et al. (1990) showed DnaK protects RNA polymerase from heat inactivation
      and reactivates heat-inactivated/aggregated RNA polymerase. This demonstrates
      DnaK's role in cellular response to unfolded proteins.
    action: ACCEPT
    reason: DnaK is a central effector of the cellular response to unfolded proteins,
      both preventing aggregation and reactivating misfolded/aggregated proteins.
    supported_by:
    - reference_id: PMID:2203539
      supporting_text: the dnaK gene product, protects the host RNA polymerase enzyme
        from heat inactivation in an ATP-independent reaction...heat-inactivated and
        aggregated RNA polymerase is both disaggregated and reactivated following
        simultaneous incubation with DnaK protein and hydrolyzable ATP
- term:
    id: GO:0034620
    label: cellular response to unfolded protein
  evidence_type: IDA
  original_reference_id: PMID:7900997
  review:
    summary: Schroder et al. (1993) showed DnaK/DnaJ/GrpE repair heat-damaged proteins.
      DnaJ associates with denatured luciferase, targets DnaK to the substrate, and
      together they prevent aggregation and enable reactivation.
    action: ACCEPT
    reason: DnaK is essential for the cellular response to unfolded/denatured proteins.
    supported_by:
    - reference_id: PMID:7900997
      supporting_text: DnaJ associated with denatured luciferase, targeted DnaK to
        the substrate and co-operated with DnaK to prevent luciferase aggregation
        at 42 degrees C
- term:
    id: GO:0043335
    label: protein unfolding
  evidence_type: IDA
  original_reference_id: PMID:20953191
  review:
    summary: Sharma et al. (2010) characterized DnaK as a polypeptide unfoldase, showing
      that Hsp70 consumes ATP to unfold a stably misfolded protein into an intermediate
      that spontaneously refolds to the native state. One DnaK consumed five ATPs
      to unfold one misfolded protein.
    action: ACCEPT
    reason: DnaK's unfoldase activity is a key mechanistic feature of its chaperone
      function. By unfolding stably misfolded species, DnaK gives them another chance
      to fold correctly. This is a genuine and important aspect of DnaK function.
    supported_by:
    - reference_id: PMID:20953191
      supporting_text: one Hsp70 molecule consumed five ATPs to effectively unfold
        a single misfolded protein into an intermediate that, upon chaperone dissociation,
        spontaneously refolded to the native state
- term:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  evidence_type: IDA
  original_reference_id: PMID:2203539
  review:
    summary: Skowyra et al. (1990) showed DnaK reactivates heat-inactivated RNA polymerase
      in an ATP hydrolysis-dependent manner. This directly demonstrates ATP-dependent
      protein folding chaperone activity.
    action: ACCEPT
    reason: Core molecular function of DnaK. GO:0140662 is the most specific and accurate
      MF term for DnaK -- it is a child of GO:0044183 (protein folding chaperone)
      combined with ATP dependence, exactly matching DnaK's mechanism.
    supported_by:
    - reference_id: PMID:2203539
      supporting_text: heat-inactivated and aggregated RNA polymerase is both disaggregated
        and reactivated following simultaneous incubation with DnaK protein and hydrolyzable
        ATP
- term:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  evidence_type: IDA
  original_reference_id: PMID:7937953
  review:
    summary: Szabo et al. (1994) defined the complete ATP hydrolysis-dependent reaction
      cycle of the DnaK/DnaJ/GrpE system mediating folding of denatured luciferase.
      They showed multiple rounds of ATP-dependent binding and release are required
      for efficient folding.
    action: ACCEPT
    reason: Definitive demonstration of DnaK's ATP-dependent chaperone cycle. This
      paper established the mechanistic framework for the DnaK system.
    supported_by:
    - reference_id: PMID:7937953
      supporting_text: A single cycle of binding and release leads to folding of only
        a fraction of luciferase molecules. Several rounds of ATP-dependent interaction
        with DnaK and DnaJ are required for fully efficient folding
- term:
    id: GO:1990169
    label: stress response to copper ion
  evidence_type: IMP
  original_reference_id: PMID:35289645
  review:
    summary: Zuily et al. (2022) showed copper induces protein aggregation in E. coli
      and that molecular chaperones including DnaK compensate for this toxicity. IMP
      evidence indicates DnaK mutant phenotype is relevant to copper stress.
    action: KEEP_AS_NON_CORE
    reason: Copper-induced protein aggregation triggers the chaperone response, with
      DnaK playing a compensatory role. This is a genuine but secondary function --
      DnaK's chaperone activity is recruited to handle copper-induced misfolding,
      rather than copper stress response being an evolved function per se.
- term:
    id: GO:0051087
    label: protein-folding chaperone binding
  evidence_type: IPI
  original_reference_id: PMID:21525416
  review:
    summary: Genest et al. (2011) showed E. coli Hsp90 (HtpG, P0A6Z3) collaborates
      with the DnaK chaperone system in client protein remodeling. DnaK and HtpG interact
      in vivo and in vitro.
    action: ACCEPT
    reason: DnaK-HtpG (Hsp90) interaction is a functionally relevant chaperone-chaperone
      binding event important for client remodeling. GO:0051087 appropriately captures
      this.
    supported_by:
    - reference_id: PMID:21525416
      supporting_text: Results indicate that E. coli Hsp90 and DnaK interact in vivo
        and in vitro, providing additional evidence to suggest that E. coli Hsp90
        and the DnaK system function together
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30442809
  review:
    summary: IPI with OmpA (P0A910) from native membrane mass spectrometry study (Chorev
      et al. 2018). DnaK was found associated with membrane protein complexes.
    action: MARK_AS_OVER_ANNOTATED
    reason: DnaK association with membrane protein OmpA likely reflects chaperone
      function at the membrane. GO:0005515 is uninformative for a general chaperone.
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IDA
  original_reference_id: PMID:9103205
  review:
    summary: Harrison et al. (1997) solved the crystal structure of GrpE bound to
      the nucleotide-free ATPase domain of DnaK, which also provided structural context
      for ATP binding. The CAFA annotation cites this as IDA evidence for ATP binding.
    action: ACCEPT
    reason: ATP binding is a core function of DnaK's N-terminal nucleotide-binding
      domain (NBD). Well-supported by structural and biochemical data.
    supported_by:
    - reference_id: PMID:9103205
      supporting_text: The structure of the nucleotide-free ATPase domain in complex
        with GrpE resembles closely that of the nucleotide-bound mammalian Hsp70 homolog
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IDA
  original_reference_id: PMID:9103205
  review:
    summary: CAFA annotation citing the GrpE-DnaK crystal structure paper. While this
      paper primarily addresses structure, the DnaK system's role in protein folding
      is implicit in the functional context of the chaperone cycle.
    action: ACCEPT
    reason: Protein folding is the core biological process of DnaK. While this specific
      paper is primarily structural, it provides context for the nucleotide cycle
      that drives folding.
- term:
    id: GO:0032991
    label: protein-containing complex
  evidence_type: IDA
  original_reference_id: PMID:9103205
  review:
    summary: Harrison et al. (1997) solved the crystal structure of the GrpE dimer
      bound to DnaK, demonstrating a stable protein-containing complex. DnaK forms
      functional complexes with its co-chaperones.
    action: ACCEPT
    reason: DnaK forms well-characterized complexes with GrpE (crystallized) and DnaJ.
      The DnaK-GrpE complex is a bona fide protein-containing complex.
    supported_by:
    - reference_id: PMID:9103205
      supporting_text: A dimer of GrpE binds asymmetrically to a single molecule of
        DnaK
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IDA
  original_reference_id: PMID:9103205
  review:
    summary: CAFA annotation. The GrpE-DnaK crystal structure paper does describe
      DnaK's substrate- binding domain and its interaction with peptide substrates.
      However, GO:0051082 is proposed for obsoletion, and DnaK's function is better
      described as ATP-dependent protein folding chaperone (GO:0140662).
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion (go-ontology#30962). DnaK's substrate
      binding is mechanistically part of its foldase cycle. The appropriate replacement
      is GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent protein
      folding chaperone), both of which DnaK already has.
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
- term:
    id: GO:0051087
    label: protein-folding chaperone binding
  evidence_type: IPI
  original_reference_id: PMID:9103205
  review:
    summary: IPI with DnaJ (P08622) from the GrpE-DnaK crystal structure study. While
      the primary focus is GrpE-DnaK, DnaJ interaction is discussed in the context
      of the chaperone cycle.
    action: ACCEPT
    reason: DnaK binding to co-chaperones DnaJ and GrpE is a core functional interaction.
      GO:0051087 appropriately captures chaperone-chaperone binding.
- term:
    id: GO:0065003
    label: protein-containing complex assembly
  evidence_type: IDA
  original_reference_id: PMID:9103205
  review:
    summary: CAFA annotation citing the GrpE-DnaK crystal structure. The complex assembly
      (DnaK with GrpE dimer) was demonstrated crystallographically. However, this
      is a byproduct of DnaK's chaperone cycle rather than a primary function.
    action: KEEP_AS_NON_CORE
    reason: DnaK does assemble into complexes with its co-chaperones (GrpE dimer,
      DnaJ), but complex assembly is not DnaK's primary function -- it is part of
      the chaperone mechanism. This is non-core.
- term:
    id: GO:0016234
    label: inclusion body
  evidence_type: IDA
  original_reference_id: PMID:15866952
  review:
    summary: Carrio and Villaverde (2005) showed by immunostaining and electron microscopy
      that DnaK localizes to the solvent-exposed surface of bacterial inclusion bodies.
      This represents DnaK's quality control function at sites of protein aggregation.
    action: ACCEPT
    reason: DnaK localization to inclusion body surfaces is consistent with its role
      in protein quality control. It is recruited to aggregates where it acts to resolubilize
      and refold misfolded proteins.
    supported_by:
    - reference_id: PMID:15866952
      supporting_text: chaperones DnaK and GroEL have been identified at the solvent-exposed
        surface of bacterial inclusion bodies and entrapped within these aggregates,
        respectively
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:2522091
  review:
    summary: Johnson et al. (1989) demonstrated DnaK and GrpE interact both in vivo
      and in vitro by coimmunoprecipitation. This was one of the earliest demonstrations
      of the DnaK-GrpE functional interaction.
    action: MODIFY
    reason: DnaK-GrpE interaction is a core co-chaperone interaction better captured
      by GO:0051087 (protein-folding chaperone binding) rather than generic protein
      binding.
    proposed_replacement_terms:
    - id: GO:0051087
      label: protein-folding chaperone binding
    supported_by:
    - reference_id: PMID:2522091
      supporting_text: Coimmunoprecipitation of DnaK+ and GrpE+ proteins from cell
        lysates with anti-DnaK antibodies demonstrated their interaction in vitro
- term:
    id: GO:0016989
    label: sigma factor antagonist activity
  evidence_type: IDA
  original_reference_id: PMID:8599944
  review:
    summary: Gamer et al. (1996) showed DnaK and DnaJ cooperatively bind free sigma32
      and inhibit its transcriptional activity in a cycle of binding and release regulated
      by GrpE and ATP. This constitutes sigma factor antagonist activity.
    action: ACCEPT
    reason: DnaK directly inhibits sigma32 activity by binding it and preventing its
      association with RNA polymerase. This is an important regulatory function and
      represents a non-core but well-characterized MF of DnaK. The chaperone-mediated
      feedback control of the heat shock response depends on this activity.
    supported_by:
    - reference_id: PMID:8599944
      supporting_text: DnaK and DnaJ cooperatively inhibit sigma32 activity in heat
        shock gene transcription and GrpE partially reverses this inhibition
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: PMID:15911532
  review:
    summary: IDA localization study (Sato et al. 2005) confirming DnaK is present
      in the E. coli cytosol under different growth conditions.
    action: ACCEPT
    reason: Cytosol is the primary localization of DnaK, confirmed by multiple independent
      studies.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: PMID:18304323
  review:
    summary: IDA from protein abundance profiling of the E. coli cytosol (Ishihama
      et al. 2008). DnaK is one of the most abundant cytosolic proteins.
    action: ACCEPT
    reason: Confirms cytosolic localization. DnaK is one of the most abundant proteins
      in the E. coli cytosol.
    supported_by:
    - reference_id: PMID:18304323
      supporting_text: we identified 1103 proteins from the cytosolic fraction of
        the Escherichia coli strain MC4100. A measure of abundance is presented for
        each of the identified proteins
- term:
    id: GO:0044183
    label: protein folding chaperone
  evidence_type: IDA
  original_reference_id: PMID:10380927
  review:
    summary: Teter et al. (1999) showed DnaK transiently associates with a wide variety
      of nascent and newly synthesized polypeptides under nonstress conditions, demonstrating
      its role as a de novo protein folding chaperone. Combined deletion of trigger
      factor and DnaK is lethal.
    action: ACCEPT
    reason: Definitive demonstration of DnaK as a de novo protein folding chaperone
      for nascent polypeptides. This is a core molecular function.
    supported_by:
    - reference_id: PMID:10380927
      supporting_text: DnaK transiently associates with a wide variety of nascent
        and newly synthesized polypeptides, with a preference for chains larger than
        30 kDa...Combined deletion of the trigger factor and DnaK genes is lethal
        under normal growth conditions
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IDA
  original_reference_id: PMID:7776367
  review:
    summary: McCarty et al. (1995) characterized the ATP hydrolysis cycle of DnaK,
      showing that ATP-bound DnaK is the primary form initiating substrate interaction.
    action: ACCEPT
    reason: Core function. ATP binding to DnaK's NBD drives its conformational cycle.
      This paper provided detailed kinetic characterization of the nucleotide cycle.
    supported_by:
    - reference_id: PMID:7776367
      supporting_text: The rapid binding kinetics lead to the conclusion that ATP-bound
        DnaK is the primary form initiating interaction with substrates for chaperone
        activity
- term:
    id: GO:0043531
    label: ADP binding
  evidence_type: IDA
  original_reference_id: PMID:19439666
  review:
    summary: Bertelsen et al. (2009) determined the solution conformation of wild-type
      DnaK complexed with ADP and substrate peptide. ADP binding stabilizes the closed-lid
      conformation of the substrate-binding domain.
    action: ACCEPT
    reason: ADP binding is an integral part of the DnaK chaperone cycle. In the ADP-bound
      state, DnaK has high affinity for substrate with slow exchange rates.
    supported_by:
    - reference_id: PMID:19439666
      supporting_text: an experimental structure for wild-type, full-length DnaK,
        complexed with the peptide NRLLLTG and with ADP
- term:
    id: GO:0043531
    label: ADP binding
  evidence_type: IDA
  original_reference_id: PMID:7776367
  review:
    summary: McCarty et al. (1995) characterized DnaK's nucleotide binding properties,
      including ADP binding and its role in the functional cycle.
    action: ACCEPT
    reason: ADP binding is essential for the DnaK chaperone cycle. GrpE stimulates
      ADP release, which is a key regulatory step.
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IDA
  original_reference_id: PMID:9145101
  review:
    summary: 'Rudiger et al. (1997) characterized DnaK interaction with peptide substrates,
      defining the substrate-binding motif: DnaK recognizes extended peptide strands
      composed of hydrophobic residues. This directly demonstrates binding to unfolded
      protein segments. However, GO:0051082 is proposed for obsoletion.'
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion (go-ontology#30962). While this
      paper directly demonstrates DnaK binding to unfolded peptide segments, this
      binding is mechanistically part of DnaK's foldase activity. The correct replacement
      is GO:0044183 (protein folding chaperone) or GO:0140662 (ATP-dependent protein
      folding chaperone). DnaK can also act as a holdase in some contexts (PMID:2203539),
      but the holdase NTR is pending.
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
    supported_by:
    - reference_id: PMID:9145101
      supporting_text: DnaK recognizes extended peptide strands composed of up to
        five consecutive hydrophobic residues within and positively charged residues
        outside the substrate binding cavity
- term:
    id: GO:0008270
    label: zinc ion binding
  evidence_type: IDA
  original_reference_id: PMID:11985624
  review:
    summary: Katayama et al. (2002) identified DnaK as a zinc-binding protein in a
      systematic search for zinc-binding proteins in E. coli using radioactive Zn(II)
      binding assay. DnaK was among nine newly identified zinc-binding proteins.
    action: UNDECIDED
    reason: The zinc-binding activity was detected in a systematic proteome-wide screen
      using radioactive zinc. While DnaK was identified, the biological significance
      of zinc binding to DnaK is unclear. DnaK does not contain a canonical zinc-finger
      or zinc-binding motif. This may represent adventitious metal binding rather
      than a biologically relevant function. There is no known role for zinc in DnaK's
      chaperone mechanism.
    supported_by:
    - reference_id: PMID:11985624
      supporting_text: 'nine zinc-binding proteins were newly identified including:
        acetate kinase (AckA), DnaK, serine hydroxymethyltransferase (GlyA)'
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: HDA
  original_reference_id: PMID:16858726
  review:
    summary: HDA annotation from complexomic study (Maddalo et al. 2006) confirming
      cytoplasmic localization of DnaK.
    action: ACCEPT
    reason: Cytoplasm is the established localization of DnaK, consistent with multiple
      studies.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: HDA
  original_reference_id: PMID:16858726
  review:
    summary: HDA annotation from complexomic study detecting DnaK in membrane fractions.
      UniProt describes DnaK as a peripheral inner membrane protein (PMID:16079137).
      This is a secondary localization.
    action: KEEP_AS_NON_CORE
    reason: DnaK is primarily cytosolic but is also found associated with membranes
      as a peripheral protein. This is a secondary localization, not the primary one.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000108
  title: Automatic assignment of GO terms using logical inference, based on on inter-ontology
    links
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10380927
  title: 'Polypeptide flux through bacterial Hsp70: DnaK cooperates with trigger factor
    in chaperoning nascent chains.'
  findings:
  - statement: DnaK functions as a de novo protein folding chaperone, transiently
      associating with nascent polypeptides under nonstress conditions.
    supporting_text: under nonstress conditions DnaK transiently associates with a
      wide variety of nascent and newly synthesized polypeptides, with a preference
      for chains larger than 30 kDa
- id: PMID:10521435
  title: Structural features required for the interaction of the Hsp70 molecular chaperone
    DnaK with its cochaperone DnaJ.
  findings: []
- id: PMID:11985624
  title: Systematic search for zinc-binding proteins in Escherichia coli.
  findings:
  - statement: DnaK identified as a zinc-binding protein in systematic proteome-wide
      screen. Biological significance unclear.
    supporting_text: 'nine zinc-binding proteins were newly identified including:
      acetate kinase (AckA), DnaK, serine hydroxymethyltransferase (GlyA)'
- id: PMID:15690043
  title: Interaction network containing conserved and essential protein complexes
    in Escherichia coli.
  findings: []
- id: PMID:15866952
  title: Localization of chaperones DnaK and GroEL in bacterial inclusion bodies.
  findings:
  - statement: DnaK localizes to the solvent-exposed surface of bacterial inclusion
      bodies.
    supporting_text: chaperones DnaK and GroEL have been identified at the solvent-exposed
      surface of bacterial inclusion bodies and entrapped within these aggregates,
      respectively
- id: PMID:15911532
  title: Localization, annotation, and comparison of the Escherichia coli K-12 proteome
    under two states of growth.
  findings: []
- id: PMID:16139413
  title: Analysis of the Escherichia coli RNA degradosome composition by a proteomic
    approach.
  findings: []
- id: PMID:16606699
  title: Large-scale identification of protein-protein interaction of Escherichia
    coli K-12.
  findings: []
- id: PMID:16858726
  title: A complexomic study of Escherichia coli using two-dimensional blue native/SDS
    polyacrylamide gel electrophoresis.
  findings: []
- id: PMID:17357109
  title: '70-kDa heat shock proteins: specific interactions with HLA-DR molecules
    and their peptide fragments.'
  findings: []
- id: PMID:17968012
  title: Analysis of sigma32 mutants defective in chaperone-mediated feedback control
    reveals unexpected complexity of the heat shock response.
  findings: []
- id: PMID:18304323
  title: Protein abundance profiling of the Escherichia coli cytosol.
  findings: []
- id: PMID:18394994
  title: Monitoring protein conformation along the pathway of chaperonin-assisted
    folding.
  findings: []
- id: PMID:19439666
  title: Solution conformation of wild-type E. coli Hsp70 (DnaK) chaperone complexed
    with ADP and substrate.
  findings:
  - statement: Solution structure of full-length DnaK in ADP-substrate bound state.
      NBD and SBD are loosely linked with dynamic relative orientation.
    supporting_text: an experimental structure for wild-type, full-length DnaK, complexed
      with the peptide NRLLLTG and with ADP
- id: PMID:19698713
  title: DnaK-mediated association of ClpB to protein aggregates. A bichaperone network
    at the aggregate surface.
  findings:
  - statement: DnaK mediates recruitment of ClpB disaggregase to protein aggregates.
    supporting_text: ClpB binding strictly depends on previous DnaK association with
      the aggregate... DnaK mediates ClpB interaction with the aggregate surface
- id: PMID:20953191
  title: The kinetic parameters and energy cost of the Hsp70 chaperone as a polypeptide
    unfoldase.
  findings:
  - statement: DnaK functions as a polypeptide unfoldase, consuming 5 ATPs to unfold
      one misfolded protein into a spontaneously refoldable intermediate.
    supporting_text: one Hsp70 molecule consumed five ATPs to effectively unfold a
      single misfolded protein into an intermediate that, upon chaperone dissociation,
      spontaneously refolded to the native state
- id: PMID:21474779
  title: Species-specific collaboration of heat shock proteins (Hsp) 70 and 100 in
    thermotolerance and protein disaggregation.
  findings: []
- id: PMID:21525416
  title: Heat shock protein 90 from Escherichia coli collaborates with the DnaK chaperone
    system in client protein remodeling.
  findings:
  - statement: E. coli Hsp90 (HtpG) and DnaK interact and collaborate in client protein
      remodeling.
    supporting_text: E. coli Hsp90 and DnaK interact in vivo and in vitro, providing
      additional evidence to suggest that E. coli Hsp90 and the DnaK system function
      together
- id: PMID:2203539
  title: The E. coli dnaK gene product, the hsp70 homolog, can reactivate heat-inactivated
    RNA polymerase in an ATP hydrolysis-dependent manner.
  findings:
  - statement: DnaK protects RNA polymerase from heat inactivation (ATP-independent
      holdase) and reactivates aggregated RNA polymerase (ATP-dependent foldase/disaggregase).
    supporting_text: the dnaK gene product, protects the host RNA polymerase enzyme
      from heat inactivation in an ATP-independent reaction...heat-inactivated and
      aggregated RNA polymerase is both disaggregated and reactivated following simultaneous
      incubation with DnaK protein and hydrolyzable ATP
- id: PMID:22065753
  title: Heat shock protein 70 kDa chaperone/DnaJ cochaperone complex employs an unusual
    dynamic interface.
  findings: []
- id: PMID:23160352
  title: Hsp70 proteins bind Hsp100 regulatory M domains to activate AAA+ disaggregase
    at aggregate surfaces.
  findings:
  - statement: DnaK activates ClpB disaggregase by binding its regulatory M domain.
    supporting_text: DnaK directly binds M-domain motif 2, increasing ClpB ATPase
      activity to unleash high ClpB threading power
- id: PMID:24561554
  title: The binary protein-protein interaction landscape of Escherichia coli.
  findings: []
- id: PMID:2522091
  title: Escherichia coli DnaK and GrpE heat shock proteins interact both in vivo
    and in vitro.
  findings:
  - statement: DnaK and GrpE functionally interact, shown by genetic suppression and
      coimmunoprecipitation.
    supporting_text: Coimmunoprecipitation of DnaK+ and GrpE+ proteins from cell lysates
      with anti-DnaK antibodies demonstrated their interaction in vitro
- id: PMID:26545493
  title: GroEL to DnaK chaperone network behind the stability modulation of σ(32)
    at physiological temperature in Escherichia coli.
  findings:
  - statement: GroEL acts upstream of DnaK in an ordered network that modulates sigma32
      stability at physiological temperature.
    supporting_text: neither DnaK nor GroEL singly can modulate sigma(32) stability
      in vivo; there is an ordered network between them, where GroEL acts upstream
      of DnaK
- id: PMID:30442809
  title: Protein assemblies ejected directly from native membranes yield complexes
    for mass spectrometry.
  findings: []
- id: PMID:35289645
  title: Copper Induces Protein Aggregation, a Toxic Process Compensated by Molecular
    Chaperones.
  findings:
  - statement: Copper induces protein aggregation and DnaK compensates for this toxicity.
    supporting_text: coli strains lacking the cytosolic chaperone DnaK or trigger
      factor are highly sensitive to copper stress
- id: PMID:7023474
  title: Positive regulatory gene for temperature-controlled proteins in Escherichia
    coli.
  findings: []
- id: PMID:7776367
  title: The role of ATP in the functional cycle of the DnaK chaperone system.
  findings:
  - statement: Detailed kinetic characterization of DnaK's ATPase cycle. ATP-bound
      DnaK initiates substrate interaction; DnaJ stimulates ATP hydrolysis to stabilize
      substrate binding.
    supporting_text: DnaK ATPase was stimulated by substrates (ninefold) and DnaJ
      (13-fold) through stimulation of the rate limiting step, gamma-phosphate cleavage
- id: PMID:7900997
  title: DnaK, DnaJ and GrpE form a cellular chaperone machinery capable of repairing
    heat-induced protein damage.
  findings:
  - statement: DnaK/DnaJ/GrpE system repairs heat-damaged luciferase both in vivo
      and in vitro. DnaJ targets DnaK to denatured substrates. ATP required for reactivation.
    supporting_text: DnaK, DnaJ and GrpE did not prevent luciferase inactivation,
      but were essential for its reactivation
- id: PMID:7937953
  title: The ATP hydrolysis-dependent reaction cycle of the Escherichia coli Hsp70
    system DnaK, DnaJ, and GrpE.
  findings:
  - statement: 'Defined the four-step chaperone cycle: substrate-DnaJ interaction,
      DnaK ATP hydrolysis and complex formation, GrpE-mediated ADP release, ATP-triggered
      substrate release. Multiple rounds needed for efficient folding.'
    supporting_text: Several rounds of ATP-dependent interaction with DnaK and DnaJ
      are required for fully efficient folding
- id: PMID:8349564
  title: Characterization of twenty-six new heat shock genes of Escherichia coli.
  findings: []
- id: PMID:8599944
  title: A cycle of binding and release of the DnaK, DnaJ and GrpE chaperones regulates
    activity of the Escherichia coli heat shock transcription factor sigma32.
  findings:
  - statement: DnaK/DnaJ bind free sigma32 and inhibit its transcriptional activity.
      GrpE/ATP drive release cycle. Central regulatory element of the heat shock response.
    supporting_text: DnaK and DnaJ cooperatively inhibit sigma32 activity in heat
      shock gene transcription and GrpE partially reverses this inhibition
- id: PMID:9103205
  title: Crystal structure of the nucleotide exchange factor GrpE bound to the ATPase
    domain of the molecular chaperone DnaK.
  findings:
  - statement: GrpE dimer binds asymmetrically to one DnaK molecule. Conformational
      change in DnaK NBD inconsistent with tight nucleotide binding explains GrpE's
      exchange mechanism.
    supporting_text: A dimer of GrpE binds asymmetrically to a single molecule of
      DnaK
- id: PMID:9145101
  title: Interaction of Hsp70 chaperones with substrates.
  findings:
  - statement: DnaK recognizes extended peptide strands with hydrophobic core and
      flanking positive charges. Defines substrate-binding specificity of Hsp70.
    supporting_text: DnaK recognizes extended peptide strands composed of up to five
      consecutive hydrophobic residues within and positively charged residues outside
      the substrate binding cavity
core_functions:
- molecular_function:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  description: DnaK is the E. coli HSP70 homolog that functions as an ATP-dependent
    protein folding chaperone (foldase). It binds unfolded polypeptide segments, undergoes
    ATP hydrolysis- driven conformational changes (with DnaJ and GrpE co-chaperones),
    and releases substrates to allow folding. Multiple rounds of binding and release
    are required for efficient folding of most substrates (PMID:7937953). DnaK also
    protects proteins from heat inactivation (holdase function, ATP-independent; PMID:2203539)
    and cooperates with trigger factor to chaperone nascent polypeptides (PMID:10380927).
  directly_involved_in:
  - id: GO:0042026
    label: protein refolding
  - id: GO:0006457
    label: protein folding
  - id: GO:0034620
    label: cellular response to unfolded protein
  - id: GO:0009408
    label: response to heat
  - id: GO:0043335
    label: protein unfolding
  locations:
  - id: GO:0005829
    label: cytosol
  - id: GO:0016234
    label: inclusion body
  supported_by:
  - reference_id: PMID:7937953
    supporting_text: Several rounds of ATP-dependent interaction with DnaK and DnaJ
      are required for fully efficient folding
  - reference_id: PMID:10380927
    supporting_text: DnaK transiently associates with a wide variety of nascent and
      newly synthesized polypeptides, with a preference for chains larger than 30
      kDa
- molecular_function:
    id: GO:0016989
    label: sigma factor antagonist activity
  description: DnaK inhibits sigma32 (RpoH) transcriptional activity by direct binding,
    constituting the chaperone-mediated negative feedback loop of the heat shock response.
    DnaK and DnaJ cooperatively sequester free sigma32, preventing its association
    with RNA polymerase. GrpE and ATP drive the release cycle (PMID:8599944).
  directly_involved_in:
  - id: GO:0045892
    label: negative regulation of DNA-templated transcription
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:8599944
    supporting_text: DnaK and DnaJ cooperatively inhibit sigma32 activity in heat
      shock gene transcription
suggested_questions:
- question: How does DnaK's holdase activity (ATP-independent aggregation prevention)
    relate to its foldase activity? Should both be annotated once the holdase NTR
    is created?
- question: Does DnaK have a genuine disaggregase function independent of ClpB, or
    is it solely a co-factor for ClpB-mediated disaggregation?
- question: Is the zinc-binding detected by Katayama et al. (PMID:11985624) biologically
    relevant or adventitious?

DnaK

Gene Description

Existing Annotations Review

Core Functions

References

Suggested Questions for Experts

📚 Additional Documentation

Deep Research Bioreason

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Deep Research Bioreason Rl

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Research report: Functional annotation of dnaK (UniProt P0A6Y8) in Escherichia coli K-12

1) Target verification (mandatory)

2) Key concepts, definitions, and current understanding

2.1 Core molecular function: ATP-dependent Hsp70 chaperone

2.2 Chaperone cycle and cochaperones (DnaJ/GrpE)

2.3 Substrate specificity and proteome-wide scope

2.4 Cellular localization and biological processes/pathways

3) Recent developments and latest research (prioritizing 2023–2024)

3.1 2024 structural/mechanistic update: DnaK–GrpE complex in E. coli

3.2 2023 computational analysis of allosteric signaling (DnaK vs BiP)

3.3 2024: infection-relevant stress roles of bacterial DnaK (enteric bacteria)

4) Current applications and real-world implementations

4.1 DnaK as an experimental workhorse in protein folding/disaggregation assays

4.2 Antimicrobial/anti-biofilm targeting concepts

5) Quantitative statistics and data relevant to functional annotation

6) Expert synthesis and interpretation (authoritative analysis grounded in evidence)

7) Limitations of the retrieved evidence

8) Key references (with dates and URLs)

Citations

Bioreason Rl Review

BioReason-Pro RL Review: DnaK (E. coli)

Functional Summary Review

Notes on thinking trace

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