DegP is an HtrA-family periplasmic protein-quality-control factor in Escherichia coli. Its mature protease-chaperone core contains a trypsin-like serine endoprotease domain followed by two PDZ domains that regulate substrate binding, allosteric activation, and the conversion of resting hexamers into larger active cages. DegP processively degrades misfolded proteins, including unfolded beta-barrel outer-membrane proteins, during envelope stress and after heat shock. It can also act as a temperature-switched chaperone, with chaperone activity favored at lower temperature and proteolysis favored at elevated temperature, and can associate peripherally with the periplasmic face of the inner membrane.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004252 serine-type endopeptidase activity | IDA PMID:2180903 The HtrA (DegP) protein, essential for Escherichia coli surv... | ACCEPT | Summary: Lipinska et al. purified mature E. coli HtrA/DegP and showed directly that it is a DFP-sensitive endopeptidase. Reason: GO:0004252 is the evidence-matched molecular function for DegP's trypsin-like HtrA protease domain. Supporting Evidence: PMID:2180903 The HtrA protein was shown to be a specific endopeptidase which was inhibited by diisopropylfluorophosphate, suggesting that HtrA is a serine protease. |
| GO:0004252 serine-type endopeptidase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA/InterPro propagation through the peptidase S1C signatures infers serine-type endopeptidase activity for DegP. Reason: The family-level inference agrees with direct biochemical evidence that DegP is a serine endoprotease. |
| GO:0004252 serine-type endopeptidase activity | IMP PMID:19255437 Bowl-shaped oligomeric structures on membranes as DegP's new... | ACCEPT | Summary: Membrane-bound DegP assemblies were shown to recruit and process substrates in oligomeric bowl-like chambers. Reason: This work supports DegP proteolysis in a membrane-associated oligomeric state and is consistent with the core serine endopeptidase activity. Supporting Evidence: PMID:19255437 These membrane-bound DegP assemblies have the capacity to recruit and process substrates in the bowl chamber |
| GO:0005515 protein binding | IPI PMID:18496527 Structural basis for the regulated protease and chaperone fu... | REMOVE | Summary: OmpC was used as a DegP cage substrate in structural studies, but the generic protein-binding term adds no information beyond substrate recognition by the DegP protease-chaperone. Reason: OmpC binding is part of DegP's regulated protease/chaperone cycle. GO:0005515 is an uninformative generic interaction term and should not be retained as a DegP molecular function. Supporting Evidence: PMID:18496527 binding of misfolded proteins transforms hexameric DegP into large, catalytically active 12-meric and 24-meric multimers |
| GO:0005515 protein binding | IPI PMID:18496527 Structural basis for the regulated protease and chaperone fu... | REMOVE | Summary: OmpA was used as a DegP cage substrate in structural studies, but the generic protein-binding term adds no information beyond substrate recognition by the DegP protease-chaperone. Reason: OmpA binding is part of DegP's regulated protease/chaperone cycle. GO:0005515 is an uninformative generic interaction term and should not be retained as a DegP molecular function. Supporting Evidence: PMID:18496527 binding of misfolded proteins transforms hexameric DegP into large, catalytically active 12-meric and 24-meric multimers |
| GO:0005515 protein binding | IPI PMID:18697939 Activation of DegP chaperone-protease via formation of large... | REMOVE | Summary: Lysozyme was used as a model substrate for DegP cage assembly and activation. Reason: The interaction records an in vitro model substrate, not a distinct endogenous DegP function; GO:0005515 is too generic to keep. |
| GO:0005515 protein binding | IPI PMID:18697939 Activation of DegP chaperone-protease via formation of large... | REMOVE | Summary: Beta-casein was used as a model unfolded substrate for DegP cage assembly and activation. Reason: The interaction records an in vitro model substrate, not a distinct endogenous DegP function; GO:0005515 is too generic to keep. |
| GO:0005515 protein binding | IPI PMID:20581825 HtrA proteases have a conserved activation mechanism that ca... | REMOVE | Summary: Beta-casein and peptide ligands were used to dissect PDZ-dependent DegP activation. Reason: The casein interaction is model-substrate evidence for the regulated serine endopeptidase mechanism. GO:0005515 is uninformative and does not represent an additional molecular function. Supporting Evidence: PMID:20581825 effector-peptide binding to the PDZ domain of DegP induces oligomer conversion from resting hexameric DegP6 into proteolytically active 12-mers and 24-mers |
| GO:0005515 protein binding | IPI PMID:20581826 Determinants of structural and functional plasticity of a wi... | REMOVE | Summary: Beta-casein was a model substrate in a mutational analysis of substrate-triggered DegP activation. Reason: The interaction is not false, but a generic IPI to a xenogeneic model substrate is not an informative DegP function. Supporting Evidence: PMID:20581826 Binding of specific peptides to PDZ domain-1 causes a local rearrangement that is allosterically transmitted to the substrate-binding pocket of the protease domain. |
| GO:0005515 protein binding | IPI PMID:21458668 Covalent linkage of distinct substrate degrons controls asse... | REMOVE | Summary: Carboxymethylated lysozyme was used to define linked active-site and PDZ1 degrons that drive DegP cage assembly. Reason: The lysozyme fragment is a model substrate for mechanistic work on DegP activation. GO:0005515 should not be retained as a stand-alone annotation for that substrate interaction. Supporting Evidence: PMID:21458668 One degron binds the DegP active site, and another degron binds a separate tethering site in PDZ1 in the crystal structure of a substrate-bound DegP dodecamer. |
| GO:0005515 protein binding | IPI PMID:24373465 DegP primarily functions as a protease for the biogenesis of... | REMOVE | Summary: OmpC was identified by photo-crosslinking as part of the natural beta-barrel OMP substrate set of DegP. Reason: The evidence supports recognition of unfolded OMPs as DegP protease substrates. GO:0005515 is too generic, and the data do not justify a direct carrier annotation for delivery of OmpC to BAM. Supporting Evidence: PMID:24373465 we identified the Ξ²-barrel outer membrane proteins (OMPs) as the major natural substrates of DegP in Escherichia coli cells. |
| GO:0005515 protein binding | IPI PMID:24373465 DegP primarily functions as a protease for the biogenesis of... | REMOVE | Summary: OmpA was identified by photo-crosslinking as part of the natural beta-barrel OMP substrate set of DegP. Reason: The evidence supports recognition of unfolded OMPs as DegP protease substrates. GO:0005515 is too generic, and the data do not justify a direct carrier annotation for delivery of OmpA to BAM. Supporting Evidence: PMID:24373465 we identified the Ξ²-barrel outer membrane proteins (OMPs) as the major natural substrates of DegP in Escherichia coli cells. |
| GO:0005515 protein binding | IPI PMID:25525882 Detecting envelope stress by monitoring Ξ²-barrel assembly. | REMOVE | Summary: The cached abstract describes OmpA/BamA/RcsF envelope-stress signaling and does not expose the DegP-OmpA interaction curated by IntAct. Reason: The row may reflect full-text interaction evidence, but GO:0005515 remains an uninformative term for DegP. No direct OMP carrier function is inferred from this OmpA interaction. |
| GO:0005515 protein binding | IPI PMID:28642151 The role of the LB structural loop and its interactions with... | REMOVE | Summary: This beta-casein interaction appears to derive from a study of the human HtrA3 protease rather than E. coli DegP. Reason: The cached abstract explicitly states that the experiments assayed human HtrA3, so it should not support an E. coli DegP protein-binding row. Supporting Evidence: PMID:28642151 Human HtrA3 protease is a proapoptotic protein, involved in embryo implantation and oncogenesis. |
| GO:0005886 plasma membrane | IDA PMID:9083020 HtrA heat shock protease interacts with phospholipid membran... | KEEP AS NON CORE | Summary: Fractionation experiments detected HtrA/DegP with the inner membrane and found that high salt partially released it from the total membrane fraction. Reason: Peripheral association with the periplasmic side of the inner membrane is plausible and reported directly, but DegP's core site of action is the periplasm rather than an integral plasma-membrane role. Supporting Evidence: PMID:9083020 HtrA was not detected by the immunoblotting technique in the periplasm or in the fraction of soluble proteins but was found in the inner membrane. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt subcellular-location mapping propagates plasma membrane from the curated DegP inner-membrane/peripheral-membrane localization. Reason: The automated row is consistent with the experimental peripheral inner-membrane observation, but periplasmic localization is the core compartment for DegP activity. |
| GO:0006457 protein folding | IMP PMID:10319814 A temperature-dependent switch from chaperone to protease in... | KEEP AS NON CORE | Summary: Spiess et al. demonstrated that DegP has chaperone activity favored at lower temperature and protease activity favored at elevated temperature. Reason: Spiess et al. provide a direct in vitro basis for DegP participation in protein folding at low temperature, but later in vivo work found that DegP primarily proteolyzes unfolded OMPs with little appreciable cellular chaperone activity. The associated molecular chaperone activity is added as a NEW GO:0044183 annotation below and treated as secondary to DegP's core protease role. Supporting Evidence: PMID:10319814 the widely conserved heat shock protein DegP (HtrA) has both general molecular chaperone and proteolytic activities. PMID:24373465 DegP primarily functions as a protease, at both low and high temperatures, to eliminate unfolded OMPs |
| GO:0006508 proteolysis | IDA PMID:18505836 Interplay of PDZ and protease domain of DegP ensures efficie... | ACCEPT | Summary: Krojer et al. showed that DegP processively degrades misfolded proteins into oligopeptides through coupled PDZ1 tethering and active-site cleavage. Reason: Processive degradation of misfolded substrates is a core DegP biological process. Supporting Evidence: PMID:18505836 DegP processively degrades misfolded proteins into peptides of defined size |
| GO:0006508 proteolysis | IDA PMID:2180903 The HtrA (DegP) protein, essential for Escherichia coli surv... | ACCEPT | Summary: The original purified-protein assay showed that DegP is an endopeptidase. Reason: DegP proteolysis is a core function supported by direct biochemical evidence. Supporting Evidence: PMID:2180903 The HtrA protein was shown to be a specific endopeptidase which was inhibited by diisopropylfluorophosphate, suggesting that HtrA is a serine protease. |
| GO:0006508 proteolysis | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA/InterPro propagation through DegP's peptidase S1C signatures infers the broad proteolysis process. Reason: The broad process mapping is correct for the experimentally characterized DegP serine endoprotease. |
| GO:0006508 proteolysis | IMP PMID:3278319 An Escherichia coli mutation preventing degradation of abnor... | ACCEPT | Summary: A degP insertion reduced degradation of a Tsr-PhoA fusion and five other abnormal periplasmic proteins. Reason: The degP mutant phenotype directly supports DegP-dependent proteolysis of abnormal periplasmic proteins. Supporting Evidence: PMID:3278319 One mutant is also defective in breakdown of five other abnormal periplasmic proteins but not of two cytoplasmic proteins. |
| GO:0006515 protein quality control | EXP PMID:17908933 Defining the roles of the periplasmic chaperones SurA, Skp, ... | ACCEPT | Summary: Genetic dissection of SurA, Skp, and DegP placed DegP in a periplasmic rescue route for OMP biogenesis when the primary SurA route fails. Reason: DegP performs protein quality control by clearing and, in vitro, assisting non-native envelope proteins. This term is appropriate, while a direct OMP assembly-process annotation is not added because SurA is the primary OMP transit factor and DegP acts mainly as a rescue/clearance factor. Supporting Evidence: PMID:17908933 The role of Skp and DegP is amplified in the absence of SurA. |
| GO:0006515 protein quality control | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT propagates protein quality control to the E. coli DegP HtrA clade. Reason: The ancestral protein-quality-control assertion is appropriate for DegP and agrees with direct evidence for misfolded-substrate degradation and chaperone activity. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001880097 Β· PANTHER:PTN001880097 SUPPORTS TRANSFER The PAINT node captures the conserved HtrA-family periplasmic protease/chaperone role represented by E. coli DegP. UniProtKB:P0C0V0 Β· degP SUPPORTS TRANSFER DegP's own experimental annotations ground the ancestral protein quality-control assertion and are valid descendant evidence, not circular propagation. |
| GO:0006515 protein quality control | IDA PMID:10319814 A temperature-dependent switch from chaperone to protease in... | ACCEPT | Summary: DegP was shown to combine a low-temperature chaperone activity with elevated-temperature protease activity. Reason: Switching between chaperone and protease activities is a direct DegP protein-quality-control mechanism. Supporting Evidence: PMID:10319814 The chaperone function dominates at low temperatures, while the proteolytic activity is present at elevated temperatures. |
| GO:0006515 protein quality control | IDA PMID:18505836 Interplay of PDZ and protease domain of DegP ensures efficie... | ACCEPT | Summary: DegP's PDZ1 and protease domain were shown to cooperate in the regulated elimination of misfolded proteins. Reason: Regulated degradation of misfolded extracytosolic proteins is a core bacterial-envelope protein-quality-control function. Supporting Evidence: PMID:18505836 This allosteric activation mechanism ensures the regulated and rapid elimination of misfolded proteins upon folding stress. |
| GO:0006515 protein quality control | IMP PMID:10319814 A temperature-dependent switch from chaperone to protease in... | ACCEPT | Summary: The temperature-dependent switch between DegP chaperone and protease modes supports its role in protein quality control. Reason: DegP is a direct-acting quality-control factor for non-native proteins rather than an indirect upstream stress regulator. Supporting Evidence: PMID:10319814 a single cellular factor can switch between two key pathways, controlling protein stability and turnover |
| GO:0006979 response to oxidative stress | IEP PMID:10517331 The Escherichia coli heat shock protease HtrA participates i... | KEEP AS NON CORE | Summary: An htrA mutant is especially sensitive to membrane-directed oxidative damage, and oxidants that partition into membranes induce HtrA synthesis. Reason: The Fe(II)/cumene hydroperoxide phenotypes are consistent with DegP clearing damaged envelope proteins, but the direct core function remains periplasmic quality-control proteolysis. Supporting Evidence: PMID:10517331 Our results show that HtrA plays a role in defense against oxidative shock |
| GO:0008233 peptidase activity | IDA PMID:18505836 Interplay of PDZ and protease domain of DegP ensures efficie... | MODIFY | Summary: DegP was assayed as a misfolded-protein peptidase, with cleavage governed by PDZ1 substrate tethering and activation of the serine protease domain. Reason: Peptidase activity is correct but too broad; GO:0004252 serine-type endopeptidase activity captures the same DegP chemistry more precisely. Proposed replacements: serine-type endopeptidase activity Supporting Evidence: PMID:18505836 PDZ1 functions as the primary substrate binding site that captures the C-terminal Z-motif of misfolded proteins and reaction intermediates and presents the N-terminal segment to the protease domain. |
| GO:0008233 peptidase activity | IDA PMID:19255437 Bowl-shaped oligomeric structures on membranes as DegP's new... | MODIFY | Summary: DegP's membrane-associated oligomers were assayed for substrate processing in vitro. Reason: Peptidase activity is a true but overly broad parent of the core serine-type endopeptidase activity. Proposed replacements: serine-type endopeptidase activity Supporting Evidence: PMID:19255437 These membrane-bound DegP assemblies have the capacity to recruit and process substrates in the bowl chamber |
| GO:0008236 serine-type peptidase activity | IMP PMID:7557477 Site-directed mutagenesis of the HtrA (DegP) serine protease... | MODIFY | Summary: Active-site mutagenesis of Ser210 and His105 abolished DegP proteolytic activity. Reason: Serine-type peptidase activity is correct but broader than serine-type endopeptidase activity, which is directly established for DegP. Proposed replacements: serine-type endopeptidase activity Supporting Evidence: PMID:7557477 Mutational alteration of Ser210 eliminated proteolytic activity of HtrA. An identical effect was observed when His105 was mutated. |
| GO:0008236 serine-type peptidase activity | ISM PMID:9041651 Evidence for PDZ domains in bacteria, yeast, and plants. | MODIFY | Summary: The 1997 sequence-analysis paper identified bacterial HtrA PDZ domains; it is architectural support rather than the best description of DegP's enzyme chemistry. Reason: DegP's molecular function should be curated to the more specific serine-type endopeptidase activity supported by direct assays. The PDZ architecture helps explain substrate recognition but should not leave the row at the generic serine-type peptidase parent. Proposed replacements: serine-type endopeptidase activity Supporting Evidence: PMID:9041651 two PDZ domains occur in bacterial high-temperature requirement A (htrA) |
| GO:0009266 response to temperature stimulus | IEP PMID:10319814 A temperature-dependent switch from chaperone to protease in... | KEEP AS NON CORE | Summary: DegP switches between chaperone and protease activities as the temperature changes. Reason: The annotation is biologically sound as broad stress-response context, but the direct functions are the chaperone and protease activities that respond to unfolded periplasmic clients. Supporting Evidence: PMID:10319814 The chaperone function dominates at low temperatures, while the proteolytic activity is present at elevated temperatures. |
| GO:0009408 response to heat | IMP PMID:2537822 Identification, characterization, and mapping of the Escheri... | KEEP AS NON CORE | Summary: The htrA locus was discovered through mutants that grow at 30 C but fail at elevated temperatures. Reason: Heat sensitivity is an important phenotype of degP disruption, but the direct function explaining that phenotype is quality-control proteolysis in the envelope. Supporting Evidence: PMID:2537822 mini-Tn10 transposon insertions in it allowed E. coli growth at 30 degrees C but prevented growth at elevated temperatures |
| GO:0009408 response to heat | IMP PMID:7557477 Site-directed mutagenesis of the HtrA (DegP) serine protease... | KEEP AS NON CORE | Summary: Protease-dead htrA alleles failed to suppress the thermosensitivity of htrA bacteria. Reason: This row correctly connects DegP protease activity to survival at high temperature, but it is a stress phenotype rather than the core molecular activity. Supporting Evidence: PMID:7557477 the proteolytic activity of HtrA is essential for the survival of cells at elevated temperatures. |
| GO:0030163 protein catabolic process | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA infers the broad protein catabolic process from DegP's HtrA protease-family features. Reason: DegP processively degrades misfolded proteins, so the broad parent process is correct even though the core review records the more specific proteolytic mechanism. |
| GO:0030288 outer membrane-bounded periplasmic space | IDA PMID:10417648 PDZ domains determine the native oligomeric structure of the... | ACCEPT | Summary: Sassoon et al. described DegP as an E. coli periplasmic heat-shock serine protease while dissecting the PDZ-domain requirements for native oligomerization. Reason: DegP is a Sec-exported periplasmic protease/chaperone, and the outer membrane-bounded periplasmic space is the correct Gram-negative cellular component. Supporting Evidence: PMID:10417648 DegP (HtrA) is a periplasmic heat shock serine protease of Escherichia coli |
| GO:0030288 outer membrane-bounded periplasmic space | IDA PMID:10517331 The Escherichia coli heat shock protease HtrA participates i... | ACCEPT | Summary: The oxidative-stress study describes HtrA/DegP as localized on the periplasmic side of the E. coli inner membrane. Reason: The mature DegP protease acts in the periplasmic envelope compartment. Supporting Evidence: PMID:10517331 localized on the periplasmic side of the inner membrane in Escherichia coli |
| GO:0030288 outer membrane-bounded periplasmic space | IDA PMID:9083020 HtrA heat shock protease interacts with phospholipid membran... | ACCEPT | Summary: Skorko-Glonek et al. combined membrane fractionation with prior periplasmic functional evidence and placed HtrA/DegP on the periplasmic side of the inner membrane. Reason: The IDA row captures the correct compartment for mature DegP activity in Gram-negative bacteria. Supporting Evidence: PMID:9083020 evidence showing that HtrA functions in the periplasm, indicate that HtrA is a peripheral membrane protein, localized on the periplasmic side of the inner membrane. |
| GO:0042597 periplasmic space | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT propagates periplasmic localization through the bacterial HtrA family node containing E. coli DegP. Reason: This broader periplasmic-space annotation is correct and consistent with direct localization evidence for DegP. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001880097 Β· PANTHER:PTN001880097 SUPPORTS TRANSFER The bacterial HtrA node appropriately carries the periplasmic localization inherited by E. coli DegP. UniProtKB:P0C0V0 Β· degP SUPPORTS TRANSFER DegP's own direct localization evidence is valid descendant evidence for the PAINT node. UniProtKB:P39099 SUPPORTS TRANSFER This source is another bacterial HtrA family member in the same PAINT trace and is consistent with the periplasmic ancestral placement. |
| GO:0042597 periplasmic space | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA infers periplasmic localization for DegP. Reason: The automated periplasmic-space annotation is a correct broader parent of the experimentally supported outer membrane-bounded periplasmic space. |
| GO:0042802 identical protein binding | IDA PMID:11919638 Crystal structure of DegP (HtrA) reveals a new protease-chap... | KEEP AS NON CORE | Summary: DegP crystallized as a hexamer assembled from two trimeric rings. Reason: Homooligomerization is essential to DegP regulation and activation, but it is structural context for the protease/chaperone machine rather than a separate core molecular function. Supporting Evidence: PMID:11919638 The DegP hexamer is formed by staggered association of trimeric rings. |
| GO:0042802 identical protein binding | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA infers identical protein binding for DegP. Reason: DegP homooligomerizes into hexamers and active higher-order cages, so the row is biologically true but non-core. |
| GO:0042802 identical protein binding | IPI PMID:11919638 Crystal structure of DegP (HtrA) reveals a new protease-chap... | KEEP AS NON CORE | Summary: The DegP crystal structure showed direct DegP-DegP contacts in the resting hexamer. Reason: Homooligomeric assembly is required for DegP's protease/chaperone cycle, but the core molecular functions are serine endoprotease and chaperone activities. Supporting Evidence: PMID:11919638 The DegP hexamer is formed by staggered association of trimeric rings. |
| GO:0042802 identical protein binding | IPI PMID:18496527 Structural basis for the regulated protease and chaperone fu... | KEEP AS NON CORE | Summary: Misfolded-protein binding was shown to convert DegP hexamers into 12- and 24-subunit cages assembled from DegP protomers. Reason: Oligomeric cage assembly is real and mechanistically important, but identical protein binding is retained only as non-core structural context. Supporting Evidence: PMID:18496527 binding of misfolded proteins transforms hexameric DegP into large, catalytically active 12-meric and 24-meric multimers |
| GO:0042802 identical protein binding | IPI PMID:18697939 Activation of DegP chaperone-protease via formation of large... | KEEP AS NON CORE | Summary: Cryo-EM showed DegP activation through 12- and 24-mer cages made from DegP trimer building blocks. Reason: This row captures the DegP-DegP interactions that form active cages, but oligomerization supports the protease/chaperone mechanism rather than an independent core function. Supporting Evidence: PMID:18697939 both oligomers are consistently assembled by blocks of DegP trimers |
| GO:0042802 identical protein binding | IPI PMID:20581825 HtrA proteases have a conserved activation mechanism that ca... | KEEP AS NON CORE | Summary: Effector-peptide binding converts DegP6 into active 12- and 24-mer oligomers. Reason: DegP-DegP association is integral to activation but is kept as non-core structural/regulatory context. Supporting Evidence: PMID:20581825 effector-peptide binding to the PDZ domain of DegP induces oligomer conversion from resting hexameric DegP6 into proteolytically active 12-mers and 24-mers |
| GO:0042802 identical protein binding | IPI PMID:20581826 Determinants of structural and functional plasticity of a wi... | KEEP AS NON CORE | Summary: Mutational and refolding experiments described how peptide-triggered DegP activation stabilizes larger oligomeric particles. Reason: DegP homooligomerization is real, but it is regulatory machinery for the protease/chaperone rather than a stand-alone core molecular function. Supporting Evidence: PMID:20581826 This activated state readily assembles into larger oligomeric particles, thus stabilizing the catalytically active form and providing a degradation cavity for protein substrates. |
| GO:0042802 identical protein binding | IPI PMID:21458668 Covalent linkage of distinct substrate degrons controls asse... | KEEP AS NON CORE | Summary: Linked substrate degrons drive the assembly and disassembly of active DegP proteolytic cages. Reason: The row correctly records DegP homooligomerization; keep it as mechanistic context for allosteric substrate activation. Supporting Evidence: PMID:21458668 Substrate cleavage and depletion results in disassembly, ensuring that DegP is proteolytically active only when sufficient quantities of protein substrates are present. |
| GO:0042802 identical protein binding | IPI PMID:21893291 Characterization of the structure and function of Escherichi... | KEEP AS NON CORE | Summary: The cached abstract centers on DegQ, but DegP homooligomerization is independently established by multiple DegP structures. Reason: The full text for the DegQ paper is unavailable, so the exact IntAct evidence behind this row is not visible in the cache. The assertion itself is correct for DegP and is retained as non-core structural context, with DegP-specific structural papers as corroborating evidence. Supporting Evidence: PMID:11919638 The DegP hexamer is formed by staggered association of trimeric rings. |
| GO:0042802 identical protein binding | IPI PMID:24373769 Substrate occupancy at the onset of oligomeric transitions o... | KEEP AS NON CORE | Summary: Native mass spectrometry showed substrate-mimicking peptides bind the resting DegP 6-mer before transition to active oligomers. Reason: The substrate-induced oligomer transitions reinforce that DegP-DegP binding is part of the activation mechanism, not a separate core molecular function. Supporting Evidence: PMID:24373769 binding of multiple substrate-mimicking peptide ligands to the DegP resting state occurs prior to the transition to an active conformation. |
| GO:0044183 protein folding chaperone | IDA PMID:10319814 A temperature-dependent switch from chaperone to protease in... | NEW | Summary: Spiess et al. directly demonstrated a general DegP chaperone activity that dominates at lower temperature. Reason: DegP's existing GOA rows include the protein folding biological process but not the underlying molecular chaperone activity. The direct temperature-switch experiments support adding GO:0044183 for the purified protein, while later OMP crosslinking work argues that the chaperone mode is not DegP's dominant in vivo function. Supporting Evidence: PMID:10319814 the widely conserved heat shock protein DegP (HtrA) has both general molecular chaperone and proteolytic activities. |
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Download this section (compressed HTML)Q: Under native growth and envelope-stress conditions, which unfolded beta-barrel OMPs are direct DegP protease substrates and which, if any, are protected by the DegP chaperone mode long enough to re-enter productive BAM assembly?
Q: How much of DegP activity occurs in soluble periplasmic cages versus lipid-associated bowl-like oligomers at the periplasmic face of the inner membrane?
Experiment: Use pulse-chase OMP biogenesis assays with catalytically inactive and chaperone-biased DegP variants to separate direct proteolytic clearance of unfolded OMPs from productive rescue into BAM-mediated assembly.
Experiment: Combine site-specific photocrosslinking of native OMP substrates with DegP oligomer-state mutants to map whether client identity biases DegP toward chaperone cages, protease cages, or membrane-associated bowl states.
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