Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0003677 DNA binding	IEA GO_REF:0000043	MODIFY	Summary: ComK is definitively a DNA-binding protein. It binds to specific AT-rich K-box motifs (AAAA-N5-TTTT) in promoter regions to activate transcription of competence genes. However, the term GO:0003677 "DNA binding" is too general - it does not capture the specific role of ComK as a sequence-specific DNA-binding transcription activator. Reason: While ComK does bind DNA, the generic "DNA binding" term is insufficiently informative. ComK is specifically a sequence-specific DNA-binding transcription factor that binds K-box regulatory elements to activate gene expression. The more specific term GO:0001216 "DNA-binding transcription activator activity" more accurately captures ComK's molecular function as it includes both the DNA binding and transcriptional activation aspects of its role. Proposed replacements: DNA-binding transcription activator activity Supporting Evidence: file:BACSU/comK/comK-deep-research-falcon.md ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination file:BACSU/comK/comK-deep-research-falcon.md ComK binds promoter K-boxes, typically recognized as a symmetric AT-rich motif AAAA–N5–TTTT; ComK forms a dimer-of-dimers (tetramer) to bind K-box elements and activate transcription at competence promoters including comG and its own comK promoter
GO:0006351 DNA-templated transcription	IEA GO_REF:0000043	MODIFY	Summary: ComK is involved in transcription as a transcription factor, but GO:0006351 "DNA-templated transcription" refers to the actual synthesis of RNA from a DNA template (the catalytic process performed by RNA polymerase). ComK is a regulatory transcription factor that modulates transcription but does not directly catalyze RNA synthesis. A more appropriate annotation would be a regulatory process term. Reason: GO:0006351 is the core transcription process (RNA synthesis from DNA template), which is carried out by RNA polymerase, not by transcription factors. ComK's role is to regulate transcription by binding to promoter elements and recruiting/activating the transcription machinery. The appropriate biological process term would be GO:0045893 "positive regulation of DNA-templated transcription" which accurately describes ComK's role in activating transcription of target genes. Proposed replacements: positive regulation of DNA-templated transcription Supporting Evidence: file:BACSU/comK/comK-deep-research-falcon.md Genome-scale analyses identified at least ~165 ComK-activated genes, many in operons preceding identifiable ComK-box motifs, including DNA uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA) file:BACSU/comK/comK-deep-research-falcon.md ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination
GO:0030420 establishment of competence for transformation	IEA GO_REF:0000120	ACCEPT	Summary: This is the most appropriate biological process term for ComK. ComK is the master regulator that directly controls the establishment of competence for transformation in B. subtilis. ComK activates all the late competence genes required for DNA uptake and processing. Reason: ComK is definitively required for the establishment of genetic competence. ComK directly activates genes encoding DNA uptake machinery (comC, comE, comF, comG operons) and DNA processing enzymes (nucA, recA). The term accurately captures the biological process in which ComK participates. The deep research confirms ComK triggers the K-state (competent state) by upregulating late competence genes. Supporting Evidence: file:BACSU/comK/comK-deep-research-falcon.md ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination file:BACSU/comK/comK-deep-research-falcon.md Genome-scale analyses identified at least ~165 ComK-activated genes, many in operons preceding identifiable ComK-box motifs, including DNA uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA)
GO:0045809 positive regulation of establishment of competence for transformation	TAS file:BACSU/comK/comK-deep-research-falcon.md	NEW	Summary: ComK is the master positive regulator of competence establishment. It activates transcription of all late competence genes and also positively regulates its own expression through an autoregulatory feedback loop. Reason: This term should be added as it specifically captures ComK's regulatory role in competence. ComK positively regulates the establishment of competence by activating transcription of late competence genes. The positive autoregulation at the comK promoter creates a bistable switch that controls entry into the competent state. This term complements GO:0030420 by specifying the regulatory relationship. Supporting Evidence: file:BACSU/comK/comK-deep-research-falcon.md ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination; it also activates its own transcription, forming a positive feedback loop (autoregulation) file:BACSU/comK/comK-deep-research-falcon.md Positive feedback at PcomK creates a switch-like, bimodal population in which only a subpopulation becomes competent (K-state)
GO:0000976 transcription cis-regulatory region binding	TAS file:BACSU/comK/comK-deep-research-falcon.md	NEW	Summary: ComK binds to specific cis-regulatory regions (K-boxes) in promoters of competence genes. The K-box is a well-characterized AT-rich motif (AAAA-N5-TTTT) that ComK recognizes as a tetramer. Reason: This molecular function term captures the specific DNA-binding activity of ComK at promoter regulatory regions. ComK binds K-box elements which are cis-regulatory regions in promoters of competence genes. This term provides more specific information about the nature of ComK's DNA binding activity compared to the generic GO:0003677. Supporting Evidence: file:BACSU/comK/comK-deep-research-falcon.md ComK binds promoter K-boxes, typically recognized as a symmetric AT-rich motif AAAA–N5–TTTT; ComK forms a dimer-of-dimers (tetramer) to bind K-box elements and activate transcription at competence promoters including comG and its own comK promoter

Core Functions

Core molecular function - ComK binds K-box motifs as a tetramer to activate transcription of late competence genes

Molecular Function:

DNA-binding transcription activator activity

Directly Involved In:

positive regulation of establishment of competence for transformation establishment of competence for transformation

References

GO_REF:0000043

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

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

file:BACSU/comK/comK-deep-research-falcon.md

Deep research report on comK competence transcription factor

ComK is a DNA-binding transcription activator that triggers the K-state

"ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination; it also activates its own transcription, forming a positive feedback loop (autoregulation)"
ComK binds K-boxes as tetramer to activate transcription

"ComK binds promoter K-boxes, typically recognized as a symmetric AT-rich motif AAAA–N5–TTTT; ComK forms a dimer-of-dimers (tetramer) to bind K-box elements and activate transcription at competence promoters including comG and its own comK promoter"
ComK regulon encompasses at least 165 genes

"Genome-scale analyses identified at least ~165 ComK-activated genes, many in operons preceding identifiable ComK-box motifs, including DNA uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA)"
ComK protein stability is controlled by MecA-ClpC/ClpP proteolysis

"MecA binds ComK and targets it to ClpC/ClpP for ATP-dependent proteolysis; ComS, produced from the quorum-sensing srf operon, competes for MecA and thereby protects/stabilizes ComK"
Positive feedback creates bistability and bimodal competence

"Positive feedback at PcomK creates a switch-like, bimodal population in which only a subpopulation becomes competent (K-state)"
Only 5-10% of cells enter the competent K-state

"Approximately 5–10% of cells express comK and enter the K-state under standard competence-inducing conditions"

Suggested Experiments

Experiment: ChIP-seq of ComK in competent B. subtilis cells to comprehensively map K-box binding sites genome-wide. This would provide definitive map of direct ComK targets versus indirect effects.

Experiment: Structural studies of ComK tetramer bound to K-box DNA. This would reveal molecular basis for K-box recognition and tetramer assembly.

Deep Research

Falcon

(comK-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 37 citations 2025-12-17T23:31:15.032269

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.

Plan and identity verification
- Identity: The target is comK (UniProt P40396), Bacillus subtilis strain 168, encoding the competence transcription factor ComK; literature consistently refers to B. subtilis ComK as the master regulator of genetic competence, matching the UniProt description and the ComK family/domain annotations (PF06338/IPR010461) (maier2020competenceandtransformation pages 3-5, berka2002microarrayanalysisof pages 1-2).

Comprehensive research report

1) Key concepts and definitions with current understanding
- Primary function: ComK is a DNA-binding transcription activator that triggers the K-state (competent state) by upregulating late competence genes required for DNA uptake, processing, and recombination; it also activates its own transcription, forming a positive feedback loop (autoregulation) (berka2002microarrayanalysisof pages 1-2, maier2020competenceandtransformation pages 1-3). URL and date: Berka et al., Mol Microbiol, 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x; Maier, Current Issues Mol Biol, 2020-01, https://doi.org/10.21775/cimb.037.057.
- DNA-binding mechanism (K-box): ComK binds promoter K-boxes, typically recognized as a symmetric AT-rich motif AAAA–N5–TTTT; ComK forms a dimer-of-dimers (tetramer) to bind K-box elements and activate transcription at competence promoters including comG and its own comK promoter (maier2020competenceandtransformation pages 3-5). URL and date: Maier, 2020-01, https://doi.org/10.21775/cimb.037.057.
- Regulon: Genome-scale analyses identified at least ~165 ComK-activated genes, many in operons preceding identifiable ComK-box motifs, including DNA uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA) (berka2002microarrayanalysisof pages 1-2). URL and date: Berka et al., 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x.
- Cellular localization of function: ComK acts in the cytoplasm as a transcription factor, binding DNA at promoter regions to recruit/assist RNA polymerase at competence gene promoters; downstream competence machinery spans the envelope (ComEA receptor, DNA translocation complexes), but ComK’s action is nuclear equivalent—i.e., on chromosomal promoters (harms2024molecularmechanismsofa pages 51-54, harms2024molecularmechanismsof pages 51-54). URL and date: Harms, 2024, unknown venue.

2) Regulatory network and pathway role
- Autoregulation and bistability: Positive feedback at PcomK creates a switch-like, bimodal population in which only a subpopulation becomes competent (K-state) (berka2002microarrayanalysisof pages 1-2, maier2020competenceandtransformation pages 1-3). URL and dates: Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x; Maier 2020-01, https://doi.org/10.21775/cimb.037.057.
- Post-translational control by MecA–ClpC/ClpP and ComS: MecA binds ComK and targets it to ClpC/ClpP for ATP-dependent proteolysis; ComS, produced from the quorum-sensing srf operon, competes for MecA and thereby protects/stabilizes ComK. This MecA–ClpC/ClpP–ComS axis constitutes a molecular switch controlling ComK stability and competence entry (berka2002microarrayanalysisof pages 1-2, maier2020competenceandtransformation pages 3-5, harms2024molecularmechanismsof pages 51-54). URLs and dates: Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x; Maier 2020-01, https://doi.org/10.21775/cimb.037.057.
- Quorum sensing and ComA→ComS coupling: The ComX pheromone activates ComP→ComA~P, inducing the srf operon that encodes ComS; higher ComS reduces ComK proteolysis and permits competence (rahmer2015constructionofa pages 1-2). URL and date: Rahmer et al., Front Microbiol, 2015-12, https://doi.org/10.3389/fmicb.2015.01431.
- Transcriptional regulators upstream of comK: AbrB, Rok, and CodY repress PcomK (and competence), while Spo0A~P relieves AbrB repression in early transition states. DegU can prime ComK action at low ComK levels; global integration links competence, stress, and developmental programs (rahmer2015constructionofa pages 1-2, harms2024molecularmechanismsofa pages 51-54). URL and date: Rahmer 2015-12, https://doi.org/10.3389/fmicb.2015.01431; Harms 2024.
- Stress sigma SigB and antisense regulation: Activation of SigB induces an antisense transcript as-comK that forms duplex with comK mRNA, leading to RNase-mediated degradation and suppression of ComK protein and transformability, thereby prioritizing stress protection over competence (harms2024molecularmechanismsof pages 75-78). URL and date: Harms, 2024.
- Additional layers and chromosomal control: Rho termination factor levels can reprogram stationary-phase transcription and indirectly block competence by disrupting comK’s positive autoregulatory loop; nucleoid structuring and RNAP-associated RNAs influence competence gene expression architecture (harms2024molecularmechanismsofa pages 51-54, harms2024molecularmechanismsof pages 51-54). URLs and dates: Harms, 2024; Bidnenko et al., PLoS Genet, 2023-02, https://doi.org/10.1371/journal.pgen.1010618.

3) Recent developments and latest research (priority 2023–2024)
- Quorum sensing policing via DegQ influences competence inputs: Work on ComQXPA signaling showed DegQ differentially tunes srfAA and aprE promoters, acting as a “policing” link to prevent overinvestment in costly processes; these srf outputs impact ComS and thereby ComK stability and competence propensity (harms2024molecularmechanismsofa pages 51-54). URL and date: Danevčič et al., Microbiol Spectrum, 2023-10, https://doi.org/10.1128/spectrum.00908-23.
- Stress–competence crosstalk via SigB-as-comK: 2024 synthesis indicates SigB-driven antisense transcription of as-comK potently represses competence under stress (e.g., light/ethanol), adding an RNA-based layer onto ComK regulation (harms2024molecularmechanismsof pages 75-78). URL and date: Harms, 2024.
- Transcription termination and competence: Stabilized Rho globally alters stationary-phase gene expression and blocks competence and sporulation, partly via lowering Spo0A and perturbing comK autoregulation (harms2024molecularmechanismsofa pages 51-54). URL and date: Bidnenko et al., PLoS Genet, 2023-02, https://doi.org/10.1371/journal.pgen.1010618.
- Proteostasis and Clp system updates: Contemporary reviews and analyses of Clp systems reaffirm MecA–ClpC/ClpP targeting of ComK and expand understanding of adaptor networks and proteolysis, highlighting broad proteostasis–competence coupling in Gram-positives (harms2024molecularmechanismsof pages 51-54). URL and date: Ishikawa et al., Genes to Cells, 2024-07, https://doi.org/10.1111/gtc.13141.
- RNAP-interacting RNAs and transcriptional heterogeneity: RIP-seq maps RNAs associated with RNAP and sigma factors in B. subtilis; single-cell transcriptomics reviews emphasize competence as a hallmark of phenotypic heterogeneity in bacterial populations, underscoring the importance of bimodal comK expression (harms2024molecularmechanismsofa pages 51-54). URLs and dates: Hausnerová et al., Nucleic Acids Res, 2024-02, https://doi.org/10.1093/nar/gkae081; Walls & Rosenthal, Transcription, 2024-03, https://doi.org/10.1080/21541264.2024.2334110.

4) Current applications and real-world implementations
- Super-competent laboratory strains via comK/comS induction: An inducible PmtlA-comKS cassette (strain REG19) yielded a 6.7-fold increase in transformation efficiency versus wild type; transformation peaked ~1.5 h after mannitol induction and saturated near ~100 ng plasmid DNA or ~3 µg chromosomal DNA per reaction, illustrating engineered control of competence in B. subtilis 168 (rahmer2015constructionofa pages 1-2). URL and date: Rahmer et al., Front Microbiol, 2015-12, https://doi.org/10.3389/fmicb.2015.01431.
- Process/strain engineering levers connected to comK: Manipulating QS (ComX/ComA→ComS), relieving repression (Rok, AbrB, CodY), tuning DegU/DegQ, or modulating Clp proteostasis (e.g., MecA or ClpC/P activity) are actionable to bias competence for transformation workflows in industrial and research settings (rahmer2015constructionofa pages 1-2, harms2024molecularmechanismsofa pages 51-54). URLs and dates: Rahmer 2015-12, https://doi.org/10.3389/fmicb.2015.01431; Harms 2024; Danevčič 2023-10, https://doi.org/10.1128/spectrum.00908-23.
- Constraints in environmental isolates and biofilms: Environmental B. subtilis strains often form robust biofilms that sharply reduce the frequency of competent cells due to cross-pathway repression (e.g., ComK directly repressing sinI; biofilm regulator SlrR repressing competence), impacting transformability in situ (boonstra2020analysesofcompetent pages 1-2). URL and date: She et al., mSystems, 2020-10, https://doi.org/10.1128/msystems.00539-20.

5) Expert opinions and analyses from authoritative sources
- Systems perspective on competence: Competence is a stochastic differentiation program shaped by positive feedback at comK, QS control over ComS, and proteolytic gating by MecA–ClpC/ClpP, ensuring only a fraction of cells engage in costly DNA uptake; single-cell and modeling work underpin this view (maier2020competenceandtransformation pages 1-3). URL and date: Maier, 2020-01, https://doi.org/10.21775/cimb.037.057.
- Integration with stress and global regulation: Reviews and syntheses emphasize that competence is deprioritized under acute stress via SigB and reshaped by global transcription termination (Rho), reflecting hierarchical resource allocation across differentiation programs (harms2024molecularmechanismsof pages 75-78, harms2024molecularmechanismsofa pages 51-54). URLs and dates: Harms, 2024; Bidnenko et al., 2023-02, https://doi.org/10.1371/journal.pgen.1010618.

6) Relevant statistics and quantitative data
- Fraction of competent cells: Approximately 5–10% of cells express comK and enter the K-state under standard competence-inducing conditions; depending on conditions/population structure, studies report 5% to as high as ~50% competent subpopulation ranges (berka2002microarrayanalysisof pages 1-2, boonstra2020analysesofcompetent pages 1-2). URLs and dates: Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x; Boonstra et al., Environ Microbiol, 2020-04, https://doi.org/10.1111/1462-2920.15005.
- Timing of expression and sampling: Differential expression between competent and non-competent subpopulations was mapped at 5.5 h and 6.5 h after induction in B. subtilis 168; dozens to hundreds of genes showed altered expression at each timepoint, confirming ComK regulon activation and broader transcriptome remodeling (boonstra2020analysesofcompetent pages 1-2). URL and date: Boonstra et al., 2020-04, https://doi.org/10.1111/1462-2920.15005.
- Regulon breadth: At least 165 genes upregulated by ComK, with 23 clusters preceded by ComK-box motifs, including key DNA uptake and recombination genes; competent cells exhibit growth arrest (“K-state”) distinct from sporulation (berka2002microarrayanalysisof pages 1-2). URL and date: Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x.
- Engineered super-competence performance: Mannitol-induced PmtlA-comKS increased transformation 6.7-fold, with peak at ~1.5 h induction and DNA saturation values as above, providing practical benchmarks for transformation optimization (rahmer2015constructionofa pages 1-2). URL and date: Rahmer 2015-12, https://doi.org/10.3389/fmicb.2015.01431.

7) Clarifications on family/domains and organism specificity
- Domain/family alignment: Literature on ComK in B. subtilis 168 consistently refers to the ComK competence transcription factor family and aligns with the UniProt PF06338/IPR010461 domain annotations, confirming we are analyzing the correct gene/protein in the specified organism (maier2020competenceandtransformation pages 3-5, berka2002microarrayanalysisof pages 1-2). URLs and dates: Maier 2020-01, https://doi.org/10.21775/cimb.037.057; Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x.

Focused mechanistic summary
- ComK binds K-boxes as a tetramer (dimer-of-dimers) and directly activates promoters of late competence genes (e.g., comG) and PcomK, producing positive feedback and bistability (maier2020competenceandtransformation pages 3-5, berka2002microarrayanalysisof pages 1-2). URL and dates: Maier 2020-01, https://doi.org/10.21775/cimb.037.057; Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x.
- Upstream signals flow through ComX/ComP/ComA to induce ComS (srf), which titrates MecA and reduces ComK degradation by ClpC/ClpP, enabling competence entry; repression by Rok, CodY, AbrB is relieved in specific states (e.g., Spo0A~P lowering AbrB), with DegU priming effects at low ComK; stress-activated SigB antisense as-comK shuts competence under acute stress (rahmer2015constructionofa pages 1-2, harms2024molecularmechanismsofa pages 51-54, harms2024molecularmechanismsof pages 75-78). URLs and dates: Rahmer 2015-12, https://doi.org/10.3389/fmicb.2015.01431; Harms 2024.
- The regulon encompasses DNA uptake (comCDEFG, comFA, comEA), DNA processing (nucA, recA), and additional genes revealed by high-resolution transcriptomics and proteomics, while competence imposes a growth-arrested physiological state (berka2002microarrayanalysisof pages 1-2, boonstra2020analysesofcompetent pages 1-2). URLs and dates: Berka 2002-03, https://doi.org/10.1046/j.1365-2958.2002.02833.x; Boonstra 2020-04, https://doi.org/10.1111/1462-2920.15005.

Limitations and open directions
- While foundational mechanisms of ComK and competence are established, newer layers involving antisense RNAs (SigB→as-comK), transcription termination (Rho), and proteostasis remodeling during stress continue to refine models of when and how competence is permitted or repressed in dynamic environments (harms2024molecularmechanismsof pages 75-78, harms2024molecularmechanismsofa pages 51-54, harms2024molecularmechanismsof pages 51-54). URLs and dates: Harms 2024; Bidnenko 2023-02, https://doi.org/10.1371/journal.pgen.1010618; Ishikawa 2024-07, https://doi.org/10.1111/gtc.13141.

References (URLs and publication dates)
- Berka RM et al. Microarray analysis of the Bacillus subtilis K-state… Mol Microbiol. 2002-03. https://doi.org/10.1046/j.1365-2958.2002.02833.x (berka2002microarrayanalysisof pages 1-2).
- Ogura M et al. Whole-genome analysis of genes regulated by ComK. J Bacteriol. 2002-05. https://doi.org/10.1128/jb.184.9.2344-2351.2002 (supports regulon scope and K-box context) (berka2002microarrayanalysisof pages 1-2).
- Maier B. Competence and Transformation in Bacillus subtilis. Current Issues Mol Biol. 2020-01. https://doi.org/10.21775/cimb.037.057 (K-box, tetramer model, network) (maier2020competenceandtransformation pages 3-5, maier2020competenceandtransformation pages 1-3).
- Boonstra M et al. Competent vs non-competent subpopulations… Environ Microbiol. 2020-04. https://doi.org/10.1111/1462-2920.15005 (quantitative subpopulation data, new players) (boonstra2020analysesofcompetent pages 1-2).
- She Q et al. Negative interplay between biofilm and competence. mSystems. 2020-10. https://doi.org/10.1128/msystems.00539-20 (biofilm-competence antagonism) (boonstra2020analysesofcompetent pages 1-2).
- Rahmer R et al. Super-competent B. subtilis 168 using PmtlA-comKS. Front Microbiol. 2015-12. https://doi.org/10.3389/fmicb.2015.01431 (applications; mechanistic summary) (rahmer2015constructionofa pages 1-2).
- Danevčič T et al. DegQ policing link for QS-regulated traits. Microbiol Spectrum. 2023-10. https://doi.org/10.1128/spectrum.00908-23 (QS–competence context) (harms2024molecularmechanismsofa pages 51-54).
- Bidnenko V et al. Rho-mediated reprogramming blocks competence/sporulation. PLoS Genet. 2023-02. https://doi.org/10.1371/journal.pgen.1010618 (global transcription effects) (harms2024molecularmechanismsofa pages 51-54).
- Hausnerová VV et al. RIP-seq RNAs interacting with RNAP. Nucleic Acids Res. 2024-02. https://doi.org/10.1093/nar/gkae081 (RNAP–RNA landscape) (harms2024molecularmechanismsofa pages 51-54).
- Walls AW & Rosenthal AZ. Bacterial phenotypic heterogeneity and scRNA-seq. Transcription. 2024-03. https://doi.org/10.1080/21541264.2024.2334110 (heterogeneity; competence context) (harms2024molecularmechanismsofa pages 51-54).
- Ishikawa F et al. ClpP/ClpC proteolysis review with MecA–ComK context. Genes to Cells. 2024-07. https://doi.org/10.1111/gtc.13141 (proteostasis link) (harms2024molecularmechanismsof pages 51-54).
- Harms M. Molecular mechanisms of Sig-dependent gene regulation in B. subtilis. 2024. (SigB→as-comK repression of competence; network synthesis) (harms2024molecularmechanismsof pages 75-78, harms2024molecularmechanismsofa pages 51-54, harms2024molecularmechanismsof pages 51-54).

References

(maier2020competenceandtransformation pages 3-5): Berenike Maier. Competence and transformation in bacillus subtilis. Current issues in molecular biology, 37:57-76, Jan 2020. URL: https://doi.org/10.21775/cimb.037.057, doi:10.21775/cimb.037.057. This article has 51 citations and is from a poor quality or predatory journal.
(berka2002microarrayanalysisof pages 1-2): Randy M. Berka, Jeanette Hahn, Mark Albano, Irena Draskovic, Marjan Persuh, Xianju Cui, Alan Sloma, William Widner, and David Dubnau. Microarray analysis of the bacillus subtilis k‐state: genome‐wide expression changes dependent on comk. Molecular Microbiology, 43:1331-1345, Mar 2002. URL: https://doi.org/10.1046/j.1365-2958.2002.02833.x, doi:10.1046/j.1365-2958.2002.02833.x. This article has 298 citations and is from a domain leading peer-reviewed journal.
(maier2020competenceandtransformation pages 1-3): Berenike Maier. Competence and transformation in bacillus subtilis. Current issues in molecular biology, 37:57-76, Jan 2020. URL: https://doi.org/10.21775/cimb.037.057, doi:10.21775/cimb.037.057. This article has 51 citations and is from a poor quality or predatory journal.
(harms2024molecularmechanismsofa pages 51-54): M Harms. Molecular mechanisms of sig-dependent gene regulation in bacillus subtilis. Unknown journal, 2024.
(harms2024molecularmechanismsof pages 51-54): M Harms. Molecular mechanisms of sig-dependent gene regulation in bacillus subtilis. Unknown journal, 2024.
(rahmer2015constructionofa pages 1-2): Regine Rahmer, Kambiz Morabbi Heravi, and Josef Altenbuchner. Construction of a super-competent bacillus subtilis 168 using the pmtla-comks inducible cassette. Frontiers in Microbiology, Dec 2015. URL: https://doi.org/10.3389/fmicb.2015.01431, doi:10.3389/fmicb.2015.01431. This article has 98 citations and is from a poor quality or predatory journal.
(harms2024molecularmechanismsof pages 75-78): M Harms. Molecular mechanisms of sig-dependent gene regulation in bacillus subtilis. Unknown journal, 2024.
(boonstra2020analysesofcompetent pages 1-2): Mirjam Boonstra, Marc Schaffer, Joana Sousa, Luiza Morawska, Siger Holsappel, Petra Hildebrandt, Praveen Kumar Sappa, Hermann Rath, Anne de Jong, Michael Lalk, Ulrike Mäder, Uwe Völker, and Oscar P. Kuipers. Analyses of competent and non‐competent subpopulations of bacillus subtilis reveal yhfw, yhxc and ncrnas as novel players in competence. Environmental Microbiology, 22:2312-2328, Apr 2020. URL: https://doi.org/10.1111/1462-2920.15005, doi:10.1111/1462-2920.15005. This article has 15 citations and is from a domain leading peer-reviewed journal.

Citations

maier2020competenceandtransformation pages 3-5
berka2002microarrayanalysisof pages 1-2
rahmer2015constructionofa pages 1-2
harms2024molecularmechanismsof pages 75-78
harms2024molecularmechanismsofa pages 51-54
harms2024molecularmechanismsof pages 51-54
boonstra2020analysesofcompetent pages 1-2
maier2020competenceandtransformation pages 1-3
https://doi.org/10.1046/j.1365-2958.2002.02833.x;
https://doi.org/10.21775/cimb.037.057.
https://doi.org/10.1046/j.1365-2958.2002.02833.x.
https://doi.org/10.3389/fmicb.2015.01431.
https://doi.org/10.3389/fmicb.2015.01431;
https://doi.org/10.1371/journal.pgen.1010618.
https://doi.org/10.1128/spectrum.00908-23.
https://doi.org/10.1111/gtc.13141.
https://doi.org/10.1093/nar/gkae081;
https://doi.org/10.1080/21541264.2024.2334110.
https://doi.org/10.1128/msystems.00539-20.
https://doi.org/10.1111/1462-2920.15005.
https://doi.org/10.21775/cimb.037.057;
https://doi.org/10.1371/journal.pgen.1010618;
https://doi.org/10.1046/j.1365-2958.2002.02833.x
https://doi.org/10.1128/jb.184.9.2344-2351.2002
https://doi.org/10.21775/cimb.037.057
https://doi.org/10.1111/1462-2920.15005
https://doi.org/10.1128/msystems.00539-20
https://doi.org/10.3389/fmicb.2015.01431
https://doi.org/10.1128/spectrum.00908-23
https://doi.org/10.1371/journal.pgen.1010618
https://doi.org/10.1093/nar/gkae081
https://doi.org/10.1080/21541264.2024.2334110
https://doi.org/10.1111/gtc.13141
https://doi.org/10.21775/cimb.037.057,
https://doi.org/10.1046/j.1365-2958.2002.02833.x,
https://doi.org/10.3389/fmicb.2015.01431,
https://doi.org/10.1111/1462-2920.15005,

OpenScientist

(comK-hypotheses/prediction-atp-binding/openscientist.md)

AIGR Gene Hypothesis Deep Research — Final Report OpenScientist openscientist-autonomous 7 citations 4 artifacts 2026-07-10T04:19:20.415263 citations file

OpenScientist final report (text/html)

OpenScientist final report (application/pdf)

OpenScientist comK ATP evidence matrix (text/csv)

OpenScientist comK GO decision table (text/csv)

AIGR Gene Hypothesis Deep Research — Final Report

ComK (BACSU, UniProt P40396): ATP binding (GO:0005524) computational prediction

Gene: comK / Competence transcription factor · Organism: Bacillus subtilis 168 (BACSU, NCBITaxon:224308) · UniProt: P40396
Predicted term under review: ATP binding (GO:0005524), from BioReason-Pro SFT
Focus type: computational_prediction · Reference context: doi:10.64898/2026.03.19.712954

Summary

The BioReason-Pro SFT prediction of ATP binding (GO:0005524) for Bacillus subtilis ComK (P40396) is refuted. ComK is a compact, 192-amino-acid, single-domain sequence-specific DNA-binding transcription factor — the master regulator of genetic competence development — and it contains no ATP-binding motif or nucleotide-binding fold. Five independent evidence types converge on this conclusion: (1) the protein sequence lacks a Walker A P-loop and a classic Walker B motif; (2) its domain family (Pfam PF06338 / InterPro IPR010461, the ComK family) carries no nucleotide-binding, kinase, or ATPase signature; (3) the curated UniProt record contains no ATP-binding annotation, keyword, or binding-site feature; (4) cryo-EM structures of the ComK–promoter complex show a DNA-binding, DNA-bending mechanism with no ATP site; and (5) mechanistic transcription studies show ComK activates transcription by stabilizing RNA polymerase at target promoters, with no ATP-hydrolysis step by ComK.

The one genuine link between ComK and ATP is indirect and does not confer ATP binding on ComK: ComK is a substrate of the ATP-dependent MecA–ClpCP protease. In that complex, the ATPase activity resides entirely in the AAA+ chaperone ClpC, while ComK is the passive degradation target. Because ComK biology is routinely discussed alongside "the ATP-dependent ClpCP protease," a model that keys on co-occurrence can easily misattribute the ATPase's ATP-dependence to the substrate. This pathway-context/co-mention bias — combined with the fact that GO:0005524 is among the most frequently over-assigned molecular-function terms — is the most plausible origin of the false-positive prediction.

Recommended curation action: Do NOT add GO:0005524. Retain and prioritize the DNA-binding transcription-factor terms that are actually supported (sequence-specific DNA binding; DNA-binding transcription activator activity), together with the well-supported process terms (DNA-templated transcription; establishment of competence for transformation). The prediction should be recorded as an over-annotation to reject.

Key Findings

Finding 1 — ComK is a sequence-specific DNA-binding transcription factor with no ATP-binding motif (prediction REFUTED)

ComK's primary molecular function is sequence-specific DNA binding driving transcriptional activation, and there is no evidence of a nucleotide-binding fold anywhere in the 192-residue protein.

Sequence-level evidence. A direct scan of the P40396 sequence found no Walker A P-loop motif (consensus [AG]x4GK[ST], the glycine-rich loop that cradles the β/γ-phosphates of ATP/GTP) and no classic Walker B motif (the hhhhDE aspartate/glutamate that coordinates the catalytic Mg²⁺–water). The absence of both halves of the canonical P-loop NTPase signature is strong negative evidence against ATP binding, because these motifs constitute the minimal structural hallmark shared across the overwhelming majority of ATP- and GTP-binding proteins.

Domain-level evidence. ComK is the founding and essentially sole member of the ComK family (Pfam PF06338 / InterPro IPR010461), a family defined by the transcription-factor function of ComK and its orthologs across Bacilli. It carries no annotation for nucleotide binding, ATPase, kinase, AAA+, or ABC architecture, and P40396 contains no auxiliary domain that could supply an ATP pocket.

Database-level evidence. UniProt annotates P40396 with keywords DNA-binding, Activator, Repressor, Transcription regulation, and with GO terms GO:0003677 (DNA binding), GO:0006351 (DNA-templated transcription), and GO:0030420 (establishment of competence for transformation). There is no ATP-binding annotation (GO:0005524) in the curated record — the prediction conflicts with, rather than derives from, the curated evidence — and there is no EC number, cofactor, or nucleotide binding-site feature.

Structural evidence. Cryo-EM structures of the complex between ComK and its promoter DNA (PMID: 34016970) demonstrate that ComK functions through mechanical forces that alter DNA curvature — an allosteric, DNA-bending mechanism — not a catalytic nucleotide-dependent step. Verified quote: "Cryo-EM structures of the complex between ComK and its promoter demonstrate that this coupling is due to mechanical forces that alter DNA curvature." No ATP or nucleotide participates in the described functional mechanism.

Mechanistic evidence. ComK activates transcription by stabilizing RNA polymerase binding at the target promoter (PMID: 14762007; verified quote: "ComK stabilizes the binding of RNA polymerase to the comG promoter"). This is a classic activator recruitment/stabilization mechanism and involves no ATP binding or hydrolysis by ComK. Foundational work (PMID: 7783616; verified quote: "we demonstrate that ComK specifically binds to DNA fragments containing promoter and upstream sequences of the genes it affects") established the sequence-specific DNA-binding activity that defines ComK, and mutational studies of the K-box AT-boxes (PMID: 17468244) confirmed base-specific DNA recognition.

Together, five independent evidence types — sequence, domain, curated database, structure, and mechanism — all point away from ATP binding and toward DNA binding. This is the central finding that refutes the seed hypothesis.

Finding 2 — ComK's only genuine ATP connection is as a substrate of the ATP-dependent MecA–ClpCP protease (explains the false positive)

The prediction most plausibly arises from pathway-context/co-mention bias, not from any intrinsic ComK property. In B. subtilis, ComK protein levels are controlled by regulated proteolysis: a ternary complex of the adaptor protein MecA and the ATP-dependent protease ClpCP targets ComK for degradation (PMID: 12598648, PMID: 19767395).

The decisive point for curation is the division of labor within this complex:

ClpC is an HSP100/Clp AAA+ ATPase; it binds and hydrolyzes ATP to power substrate unfolding and translocation. The ATP-binding activity belongs to ClpC.
MecA is the adaptor that recognizes ComK, delivers it to ClpC, and stimulates ClpC's ATPase activity.
ComK is the passive substrate. It contributes no ATP-binding or ATPase activity; it is the protein being degraded.

Verified quotes: "A complex of ClpC with the protease ClpP and the adaptor protein MecA also controls competence development by regulated proteolysis of the transcription factor ComK" (PMID: 12598648); "the degradation of the competence transcription factor ComK is mediated by a ternary complex involving the adaptor protein MecA and the ATP-dependent protease ClpCP" (PMID: 19767395).

Because ComK is routinely discussed in the same sentences as the "ATP-dependent protease ClpCP," a text- or co-occurrence-influenced model can mis-attribute the ATP-dependence of the degradation machinery to ComK itself. This is a textbook instance of pathway-context bias generating a false ATP-binding call for a protein that is merely a substrate. Notably, no paralog with an ATPase fold shares the ComK family, so paralog over-annotation can be ruled out as the source.

Mechanistic Model / Interpretation

The following schematic separates what ComK actually does from the ATP-dependent process in which ComK is a substrate, clarifying why GO:0005524 is a misassignment.

   ComK's ACTUAL molecular function (no ATP involved)
   ───────────────────────────────────────────────────
 ComK (192 aa, PF06338)
        │
     sequence-specific DNA binding
(K-box: paired AT-boxes, AAAA-N5-TTTT)
        │
        ▼
┌───────────────────────────────────┐
│  bends / curves promoter DNA       │  (cryo-EM, PMID 34016970)
│  stabilizes RNA polymerase binding │  (PMID 14762007)
└───────────────────────────────────┘
        │
        ▼
  activation of the K-regulon → competence
 (GO:0030420, GO:0006351)

   NO Walker A / Walker B / P-loop  →  NO ATP binding by ComK


   The ATP link is EXTERNAL to ComK (ComK = substrate)
   ───────────────────────────────────────────────────
      MecA (adaptor) ── recognizes ──► ComK (SUBSTRATE)
                          │
ClpC (AAA+ ATPase) ── ATP hydrolysis ──► unfolds / translocates
                          │
ClpP (protease) ─────────────────► degrades ComK

      ATP is bound & hydrolyzed by ClpC, NOT by ComK
      (PMID 12598648, PMID 19767395)

Interpretation. The two findings form a single coherent narrative. ComK is a compact, single-domain DNA-binding activator whose entire biochemistry — K-box recognition, DNA bending, and RNA polymerase recruitment — is nucleotide-independent. Its cellular abundance is set post-translationally by an ATP-powered protease, but that ATP dependence is a property of ClpC, not ComK. A predictor keying on the strong statistical association between "ComK" and "ATP-dependent ClpCP" in the literature would produce exactly the false-positive ATP-binding call observed. Distinguishing the substrate (ComK) from the enzyme (ClpC) is the crux of the correct curation decision.

Comparison table: expected features of an ATP-binding protein vs. observed for ComK

Feature diagnostic of ATP binding	Expected if hypothesis true	Observed for ComK (P40396)	Verdict
Walker A P-loop (`[AG]x4GK[ST]`)	Present	Absent	Refutes
Walker B motif (hhhhDE)	Present	Absent	Refutes
P-loop NTPase / AAA+ / ABC / kinase domain	Present	Absent (ComK family PF06338 only)	Refutes
UniProt ATP-binding keyword / site feature	Present	Absent	Refutes
GO:0005524 in curated record	Present	Absent	Refutes
ATP/nucleotide density in structure	Present	Absent (DNA-bound cryo-EM)	Refutes
Functional need for ATP in mechanism	Required	Not required (recruitment / DNA bending)	Refutes
Sequence-specific DNA-binding activity	Not required	Present, defining	Competing correct function

Evidence Base / Evidence Matrix

Citation	Evidence type	Direction	Claim tested	Key finding	Context	Confidence / limitations
This analysis (P40396 seq)	Computational (motif scan)	Refutes	ComK contains an ATP-binding motif	No Walker A P-loop, no classic Walker B in 192 aa	In silico	High; motif absence is strong but not exhaustive of atypical folds
UniProt P40396 (database)	Review/database	Refutes	Curated ATP-binding function exists	No ATP keyword/GO; only DNA-binding & transcription terms	Curated record	High; database-level orientation
Pfam PF06338 / InterPro IPR010461	Structural/evolutionary	Refutes	Nucleotide-binding fold in family	ComK-specific family; no NTPase/kinase signature	Domain model	High; no P-loop lineage
PMID: 34016970	Structural (cryo-EM)	Refutes / qualifies	Mechanism requires ATP	Function via DNA binding + DNA-curvature allostery; no ATP site	B. subtilis, in vitro	High
PMID: 7783616	Direct assay (DNA binding)	Supports DNA (competing correct fn)	Primary function is DNA binding	ComK binds specific promoter/upstream DNA	B. subtilis	High; establishes core function
PMID: 14762007	Direct assay (in vitro transcription)	Refutes (ATP not needed)	Activation is ATP-dependent	ComK stabilizes RNAP binding; no ATP step	B. subtilis, in vitro	High
PMID: 17468244	Mutant / binding	Qualifies (supports DNA)	DNA sequence specificity	K-box AT-box T2 base critical for binding/activation	B. subtilis	High
PMID: 15598897	Mutant / promoter mapping	Qualifies (regulatory context)	How comK is regulated	DegU binds inverted repeat in comK promoter	B. subtilis	Medium; concerns comK regulation, not ComK ATP
PMID: 12598648	Interaction / proteolysis	Competing / qualifies	ComK–ATP link	ComK is substrate of ATP-dependent ClpCP; ATPase is ClpC	B. subtilis	High; explains misassignment
PMID: 19767395	Interaction / proteolysis	Competing / qualifies	ComK ATP link is intrinsic	MecA targets ComK to ClpCP; ATP dependence is ClpCP's	B. subtilis	High; ComK is substrate, not ATP binder

GO Curation Implications

Lead requiring curator verification:

Do NOT add GO:0005524 (ATP binding). The molecular-function prediction is a false positive. No sequence motif, domain, curated annotation, structural feature, or mechanistic requirement supports ATP binding by ComK. If GO:0005524 has been auto-propagated onto P40396, it should be rejected / not accepted.
Retain and prioritize the informative Molecular Function terms that are actually supported:
GO:0003677 — DNA binding (already curated; supported by PMID: 7783616).
GO:0043565 — sequence-specific DNA binding and GO:0001216 — DNA-binding transcription activator activity as the precise MF terms (K-box specificity, PMID: 17468244; RNAP stabilization, PMID: 14762007). These are strictly more informative than "protein binding" and should be preferred. ComK also acts as a repressor in some contexts.
Retain the Biological Process terms: GO:0006351 (DNA-templated transcription) / GO:0006355 (regulation of transcription) and GO:0030420 (establishment of competence for transformation).
Frame the ATP link correctly, if annotated at all: ComK's relationship to ATP is as a substrate of an ATP-dependent protease (ClpCP). Any ATP-related annotation belongs to ClpC, not ComK. This relationship should not become an ATP-binding MF term on ComK.

Summary GO decision table:

GO term	Aspect	Recommended action	Basis
GO:0005524 ATP binding	MF	Reject / do not add	No motif, domain, structure, or mechanism; substrate-only ATP link
GO:0003677 DNA binding	MF	Retain	PMID 7783616
GO:0043565 sequence-specific DNA binding	MF	Add / upgrade (more specific)	PMID 17468244, 34016970
GO:0001216 DNA-binding transcription activator activity	MF	Add / consider	PMID 14762007
GO:0006351 / GO:0006355 transcription (regulation)	BP	Retain	Curated
GO:0030420 establishment of competence	BP	Retain	Curated

Mechanistic Scope

Immediate molecular function under test: whether ComK directly binds ATP (GO:0005524). The answer is no. ComK's direct, primary molecular activity is sequence-specific binding to K-box DNA elements (paired AT-boxes) and, through that binding, DNA bending and stabilization of RNA polymerase at target promoters.

What must be kept separate (not ComK's direct molecular function):
- Downstream developmental outcome: establishment of genetic competence, DNA uptake, and homologous recombination — consequences of ComK's transcriptional activity, not evidence for ATP binding.
- Pathway context: ATP-dependent proteolysis of ComK by MecA–ClpCP — an external regulatory process in which ComK is the substrate and ClpC is the ATPase.
- Upstream regulation: DegU binding to the comK promoter (PMID: 15598897) governs comK expression, unrelated to any ComK ATP activity.

The ATP-binding hypothesis fails precisely because it conflates a pathway-level ATP dependence (proteolysis) with a gene-product-level molecular function (nucleotide binding).

Conflicts and Alternatives

Substrate-vs-enzyme confusion (most likely artifact): The strongest ComK–ATP link in the literature is that ComK is a substrate of the ATP-dependent MecA–ClpCP protease (PMID: 12598648, PMID: 19767395). Attributing ClpC's ATP dependence to ComK is the error.
Frequency / prior bias: GO:0005524 is one of the most common MF terms; a model with a strong prior can over-assign it in the absence of any real signal.
Paralog / family confusion — ruled out: ComK is the sole defining member of PF06338; there is no ATP-binding paralog within the family that could seed annotation transfer.
Organism-specific differences — none: ComK's role as a competence transcription factor is conserved across Bacilli; no ortholog is reported to have acquired a nucleotide-binding domain.
In vitro-only artifact — none: No in vitro study reports ATP binding by ComK; the relevant assays (DNA binding, transcription activation) are ATP-independent for ComK.
Database carry-over — absent: UniProt P40396 does not carry GO:0005524, so the prediction contradicts, rather than inherits from, the curated record.

All conflicts point the same direction: away from ATP binding by ComK.

Limitations and Knowledge Gaps

Motif scan scope. The Walker A/B scan used canonical consensus patterns; degenerate or atypical nucleotide pockets can occasionally escape simple motif matching. Why it matters: a hidden atypical site would be missed by motif search alone. Resolution: the gap is largely closed by the DNA-bound cryo-EM structure and by the ComK-family domain assignment, neither of which reveals a nucleotide pocket; a full HMMER/InterProScan and structure-based pocket analysis (e.g., on the AlphaFold model) would formally confirm.
Direct negative biochemical assay. No published experiment explicitly reports the absence of ATP binding by ComK (negative results are rarely published). Why it matters: absence of ATP binding is inferred from motif/domain/structure/mechanism rather than a dedicated binding assay. Resolution: an ITC, DSF/thermal-shift, DRaCALA, or ATP-agarose pulldown assay would provide a direct negative control.
Structure interpretation is literature-based. The cryo-EM conclusion is drawn from the published report (PMID: 34016970); the raw coordinates were not re-analyzed here for ligand density (none expected). Resolution: inspect the deposited PDB/EMDB entry for any nucleotide ligand.
Provenance of the prediction. The exact features BioReason-Pro SFT used are unknown. Why it matters: confirming co-mention/frequency bias would strengthen the "reject" recommendation. Resolution: inspect model attributions if available.

None of these gaps materially weakens the refutation; they are avenues for formal confirmation.

Discriminating Tests / Proposed Follow-up Experiments

Concrete, prioritized actions to definitively distinguish ATP binding from the established DNA-binding function:

ITC or thermal-shift (DSF) with ATP on purified ComK (± Mg²⁺). Expected if hypothesis true: measurable K_d / thermal stabilization. Predicted outcome: no binding — a clean direct negative control. Highest-value, low-cost test.
Inspect the ComK–DNA cryo-EM structure / PDB (PMID: 34016970) for any bound nucleotide density or P-loop-like pocket. Expected: none.
Structure-based pocket/ligand-site prediction on an AlphaFold model of P40396 and superposition against known P-loop NTPases. Expected: a DNA-binding surface, not an ATP pocket.
Full domain/HMM re-scan (InterProScan, HMMER vs. Pfam-A). Expected: PF06338-only architecture; no AAA+/P-loop/kinase domain.
ATP-agarose or DRaCALA binding assay on purified ComK. Predicted: negative — formally closes the biochemical gap.
Attribution audit of the BioReason-Pro prediction: test whether the ATP call tracks co-mention with ClpCP/MecA text, confirming frequency/pathway-context bias as the mechanism of the false positive.

Curation Leads (require curator verification)

Action: Reject the ATP binding (GO:0005524) prediction for P40396; do not add. Record as computational over-annotation driven by co-mention with the ATP-dependent ClpCP protease and general frequency bias.
Candidate MF terms to retain/add (more informative than "protein binding"):
GO:0003677 DNA binding (retain) — snippet to verify: "we demonstrate that ComK specifically binds to DNA fragments containing promoter and upstream sequences of the genes it affects" (PMID: 7783616).
GO:0043565 sequence-specific DNA binding / GO:0001216 DNA-binding transcription activator activity — snippets to verify: "Cryo-EM structures of the complex between ComK and its promoter demonstrate that this coupling is due to mechanical forces that alter DNA curvature" (PMID: 34016970); "ComK stabilizes the binding of RNA polymerase to the comG promoter" (PMID: 14762007).
BP terms to retain: GO:0006351 / GO:0006355 (transcription / regulation of transcription), GO:0030420 (establishment of competence).
Note for the record (optional): ComK is a substrate of the ATP-dependent MecA–ClpCP protease — snippets to verify: "A complex of ClpC with the protease ClpP and the adaptor protein MecA also controls competence development by regulated proteolysis of the transcription factor ComK" (PMID: 12598648); "the degradation of the competence transcription factor ComK is mediated by a ternary complex involving the adaptor protein MecA and the ATP-dependent protease ClpCP" (PMID: 19767395). This explains the ATP association without implying ATP binding by ComK.
Suggested curator question: Confirm whether the ComK cryo-EM/PDB entry shows any bound nucleotide (expected: none); and whether GO:0005524 was propagated from an electronic pipeline.
Suggested experiment: ATP-agarose / DRaCALA / ITC assay on purified ComK to formally close the gap (expected negative).

Conclusion

The ATP-binding (GO:0005524) prediction for Bacillus subtilis ComK (P40396) is refuted. ComK is a 192-amino-acid, single-domain (ComK family, PF06338/IPR010461) sequence-specific DNA-binding transcription factor with no Walker A/B motifs or nucleotide-binding fold. Sequence, domain, curated-database, structural (cryo-EM, PMID: 34016970), and mechanistic (PMID: 14762007) evidence unanimously support DNA binding and RNA polymerase stabilization rather than ATP binding. The only genuine ATP link is that ComK is a substrate of the ATP-dependent MecA–ClpCP protease, in which the ATPase is ClpC — the most plausible source of the frequency/pathway-context bias behind this misassignment. GO:0005524 should not be added; the informative, supported terms are sequence-specific DNA binding and DNA-binding transcription activator activity.

Artifacts

📚 Additional Documentation

Bioreason Rl Predictions

(comK-bioreason-rl-predictions.md)

BioReason Chat Export

Exported on March 22, 2026 at 02:23 AM

Organism: Bacillus subtilis

Sequence:

MSQKTDAPLESYEVNGATIAVLPEEIDGKICSKIIEKDCVFYVNMKPLQIVDRSCRFFGSSYAGRKAGTYEVTKISHKPPIMVDPSNQIFLFPTLSSTRPQCGWISHVHVKEFKATEFDDTEVTFSNGKTMELPISYNSFENQVYRTAWLRTKFQDRIDHRVPKRQEFMLYPKEERTKMIYDFILRELGERY

Thinking Trace

I begin with the InterPro architecture: a single, nearly full-length competence factor signature, IPR010461 (Competence protein ComK family) spanning residues 5–191. This solitary, lineage-defining domain occupies essentially the entire polypeptide, which indicates a dedicated, non-modular regulator rather than a multi-domain enzyme. ComK-family architectures in Gram-positive bacteria are characterized by sequence features that favor nucleic-acid-associated transcriptional regulation and assembly of competence-specific complexes. The absence of additional catalytic or transmembrane modules implies a soluble regulator that exerts function through macromolecular binding and complex formation rather than through enzymatic turnover or membrane transport.

From this architecture, the molecular function is best explained by multivalent macromolecular binding that enables transcriptional control. A full-length competence regulator typically binds both DNA and partner proteins to switch on the competence regulon. This supports a core functional profile centered on protein binding (GO:0005515) as the minimal, well-supported activity that enables higher-order regulation and complex assembly. The ComK-family signature causally points to a transcriptional switch behavior: the domain’s prevalence in competence systems indicates that the protein’s primary biochemical role is to assemble and stabilize regulatory assemblies that activate competence gene expression.

These molecular activities feed directly into the biological process of genetic competence. By orchestrating the transcriptional state that enables uptake and processing of extracellular DNA, the regulator drives the broader competence program. Thus, the process aligns with genetic competence (GO:0009294), where the regulatory cascade licenses DNA acquisition and downstream recombination/repair pathways.

The cellular context follows from the soluble, non-membranous architecture and competence-specific transcriptional control. With no signal peptides or transmembrane segments and a regulator-like domain, the protein operates in the cytoplasm, consistent with a soluble assembly hub coordinating transcriptional machinery and competence-specific factors; this matches a cytoplasmic localization (GO:0005737).

Mechanistically, I infer that the ComK-family core forms a cytoplasmic regulatory scaffold that nucleates competence assemblies. By binding partner proteins and likely engaging promoter-proximal DNA, it elevates transcription of competence genes and couples them to downstream uptake pathways. This model predicts transient interactions with competence transcriptional modules and uptake machinery: cytoplasmic competence factors that drive DNA acquisition, along with general transcriptional regulators and RNA-associated assemblies. Such partnerships would allow the protein to gate the competence regulon, synchronize transcriptional activation with cytoplasmic uptake readiness, and ensure spatiotemporal fidelity of the competence state.

Functional Summary

A cytoplasmic competence regulator in Bacillus subtilis that assembles and stabilizes macromolecular complexes to activate the competence program. By using a competence-specific regulatory core, it binds partner proteins to orchestrate transcriptional switching of the competence regulon and coordinate downstream DNA uptake readiness. Its soluble architecture and regulatory role position it as a cytoplasmic hub that couples transcriptional control with the broader machinery of genetic competence.

UniProt Summary

Involved in genetic competence.

InterPro Domains

Competence protein ComK (IPR010461, family) — residues 5-191

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), protein binding (GO:0005515)

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), cellular component organization or biogenesis (GO:0071840), cellular component organization (GO:0016043), cellular component biogenesis (GO:0044085), protein-containing complex organization (GO:0043933), cellular component assembly (GO:0022607), protein-containing complex assembly (GO:0065003), protein complex oligomerization (GO:0051259), protein homooligomerization (GO:0051260)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), intracellular immature spore (GO:0042763)

Generated by BioReason

Bioreason Rl Review

(comK-bioreason-rl-review.md)

BioReason-Pro RL Review: comK (B. subtilis)

Source: comK-bioreason-rl-predictions.md

Correctness: 3/5
Completeness: 2/5

Functional Summary Review

The BioReason functional summary reads:

A cytoplasmic competence regulator in Bacillus subtilis that assembles and stabilizes macromolecular complexes to activate the competence program. By using a competence-specific regulatory core, it binds partner proteins to orchestrate transcriptional switching of the competence regulon and coordinate downstream DNA uptake readiness. Its soluble architecture and regulatory role position it as a cytoplasmic hub that couples transcriptional control with the broader machinery of genetic competence.

The summary correctly identifies ComK as a cytoplasmic competence regulator and links it to genetic competence (GO:0009294 / GO:0030420). However, it fundamentally mischaracterizes the molecular function. The curated review establishes that ComK is a DNA-binding transcription activator (GO:0001216) that binds to specific K-box motifs (AAAA-N5-TTTT) as a tetramer (dimer-of-dimers) to activate transcription of late competence genes. BioReason instead describes ComK as a "macromolecular complex assembler" with "protein binding" (GO:0005515) as its primary molecular function, and the predicted GO terms list only protein binding and protein complex assembly terms -- completely missing DNA binding, transcription factor activity, or transcription regulation.

This is a significant error. The curated review proposes DNA-binding transcription activator activity as the core MF and positive regulation of establishment of competence for transformation (GO:0045809) as the core BP. BioReason's narrative vaguely alludes to "transcriptional switching" but assigns the wrong molecular function, treating ComK more like a scaffold than the sequence-specific DNA-binding transcription factor it is.

The summary also omits ComK's positive autoregulatory feedback loop, the bistable switch generating bimodal population behavior (5-10% K-state cells), and the MecA-ClpC-ClpP proteolytic control mechanism -- all central to understanding ComK biology.

Comparison with interpro2go:

The interpro2go annotations for comK are minimal. The only InterPro domain is IPR010461 (Competence protein ComK), which maps to generic protein binding and protein homooligomerization terms in GO. BioReason closely recapitulates these interpro2go-level predictions without adding meaningful insight. Both miss the DNA-binding transcription factor activity that is ComK's actual function. BioReason provides no advantage over interpro2go here.

Notes on thinking trace

The trace acknowledges the single-domain architecture and correctly infers a regulatory rather than enzymatic role. However, it defaults to "protein binding" as the molecular function, likely because the InterPro entry for the ComK family does not explicitly annotate DNA-binding activity. The trace does mention "nucleic-acid-associated transcriptional regulation" early on but does not carry this through to the GO term predictions.

📄 View Raw YAML

id: P40396
gene_symbol: comK
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:224308
  label: Bacillus subtilis (strain 168)
description: ComK is the master transcriptional regulator of genetic competence in
  Bacillus subtilis, functioning as a DNA-binding transcription activator that controls
  the expression of late competence genes required for DNA uptake, processing, and
  recombination. ComK binds to specific AT-rich motifs called K-boxes (consensus AAAA-N5-TTTT)
  in promoter regions as a tetramer (dimer-of-dimers) to activate transcription of
  target genes including the comC, comE, comF, comG operons encoding DNA uptake machinery,
  as well as recA and nucA involved in DNA processing. A critical feature of ComK
  regulation is its positive autoregulation at its own promoter (PcomK), which creates
  a bistable switch leading to bimodal population behavior where only 5-10% of cells
  enter the competent K-state. ComK protein levels are tightly controlled through
  post-translational degradation by the MecA-ClpC-ClpP protease system; the adaptor
  protein MecA targets ComK to the ClpC-ClpP protease for degradation. This proteolytic
  control is relieved by ComS, a small protein produced from the quorum-sensing regulated
  srf operon, which competes with ComK for MecA binding and thereby stabilizes ComK.
  ComK expression is also negatively regulated at the transcriptional level by multiple
  repressors including AbrB, Rok, and CodY, with Spo0A-P relieving AbrB repression
  during transition to stationary phase. The ComK regulon encompasses at least 165
  genes, making it a central hub connecting quorum sensing, nutritional status, and
  stress responses to the developmental decision to enter the competent state.
references:
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: file:BACSU/comK/comK-deep-research-falcon.md
  title: Deep research report on comK competence transcription factor
  findings:
  - statement: ComK is a DNA-binding transcription activator that triggers the K-state
    supporting_text: ComK is a DNA-binding transcription activator that triggers the
      K-state (competent state) by upregulating late competence genes required for
      DNA uptake, processing, and recombination; it also activates its own transcription,
      forming a positive feedback loop (autoregulation)
  - statement: ComK binds K-boxes as tetramer to activate transcription
    supporting_text: "ComK binds promoter K-boxes, typically recognized as a symmetric\
      \ AT-rich motif AAAA\u2013N5\u2013TTTT; ComK forms a dimer-of-dimers (tetramer)\
      \ to bind K-box elements and activate transcription at competence promoters\
      \ including comG and its own comK promoter"
  - statement: ComK regulon encompasses at least 165 genes
    supporting_text: Genome-scale analyses identified at least ~165 ComK-activated
      genes, many in operons preceding identifiable ComK-box motifs, including DNA
      uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA)
  - statement: ComK protein stability is controlled by MecA-ClpC/ClpP proteolysis
    supporting_text: MecA binds ComK and targets it to ClpC/ClpP for ATP-dependent
      proteolysis; ComS, produced from the quorum-sensing srf operon, competes for
      MecA and thereby protects/stabilizes ComK
  - statement: Positive feedback creates bistability and bimodal competence
    supporting_text: Positive feedback at PcomK creates a switch-like, bimodal population
      in which only a subpopulation becomes competent (K-state)
  - statement: Only 5-10% of cells enter the competent K-state
    supporting_text: "Approximately 5\u201310% of cells express comK and enter the\
      \ K-state under standard competence-inducing conditions"
existing_annotations:
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: ComK is definitively a DNA-binding protein. It binds to specific AT-rich
      K-box motifs (AAAA-N5-TTTT) in promoter regions to activate transcription of
      competence genes. However, the term GO:0003677 "DNA binding" is too general
      - it does not capture the specific role of ComK as a sequence-specific DNA-binding
      transcription activator.
    action: MODIFY
    reason: While ComK does bind DNA, the generic "DNA binding" term is insufficiently
      informative. ComK is specifically a sequence-specific DNA-binding transcription
      factor that binds K-box regulatory elements to activate gene expression. The
      more specific term GO:0001216 "DNA-binding transcription activator activity"
      more accurately captures ComK's molecular function as it includes both the DNA
      binding and transcriptional activation aspects of its role.
    proposed_replacement_terms:
    - id: GO:0001216
      label: DNA-binding transcription activator activity
    supported_by:
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: ComK is a DNA-binding transcription activator that triggers
        the K-state (competent state) by upregulating late competence genes required
        for DNA uptake, processing, and recombination
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: "ComK binds promoter K-boxes, typically recognized as a symmetric\
        \ AT-rich motif AAAA\u2013N5\u2013TTTT; ComK forms a dimer-of-dimers (tetramer)\
        \ to bind K-box elements and activate transcription at competence promoters\
        \ including comG and its own comK promoter"
- term:
    id: GO:0006351
    label: DNA-templated transcription
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: ComK is involved in transcription as a transcription factor, but GO:0006351
      "DNA-templated transcription" refers to the actual synthesis of RNA from a DNA
      template (the catalytic process performed by RNA polymerase). ComK is a regulatory
      transcription factor that modulates transcription but does not directly catalyze
      RNA synthesis. A more appropriate annotation would be a regulatory process term.
    action: MODIFY
    reason: GO:0006351 is the core transcription process (RNA synthesis from DNA template),
      which is carried out by RNA polymerase, not by transcription factors. ComK's
      role is to regulate transcription by binding to promoter elements and recruiting/activating
      the transcription machinery. The appropriate biological process term would be
      GO:0045893 "positive regulation of DNA-templated transcription" which accurately
      describes ComK's role in activating transcription of target genes.
    proposed_replacement_terms:
    - id: GO:0045893
      label: positive regulation of DNA-templated transcription
    supported_by:
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: Genome-scale analyses identified at least ~165 ComK-activated
        genes, many in operons preceding identifiable ComK-box motifs, including DNA
        uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA)
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: ComK is a DNA-binding transcription activator that triggers
        the K-state (competent state) by upregulating late competence genes required
        for DNA uptake, processing, and recombination
- term:
    id: GO:0030420
    label: establishment of competence for transformation
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: This is the most appropriate biological process term for ComK. ComK is
      the master regulator that directly controls the establishment of competence
      for transformation in B. subtilis. ComK activates all the late competence genes
      required for DNA uptake and processing.
    action: ACCEPT
    reason: ComK is definitively required for the establishment of genetic competence.
      ComK directly activates genes encoding DNA uptake machinery (comC, comE, comF,
      comG operons) and DNA processing enzymes (nucA, recA). The term accurately captures
      the biological process in which ComK participates. The deep research confirms
      ComK triggers the K-state (competent state) by upregulating late competence
      genes.
    supported_by:
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: ComK is a DNA-binding transcription activator that triggers
        the K-state (competent state) by upregulating late competence genes required
        for DNA uptake, processing, and recombination
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: Genome-scale analyses identified at least ~165 ComK-activated
        genes, many in operons preceding identifiable ComK-box motifs, including DNA
        uptake and recombination loci (e.g., comCDEFG, comFA, comEA, nucA, recA)
- term:
    id: GO:0045809
    label: positive regulation of establishment of competence for transformation
  evidence_type: TAS
  original_reference_id: file:BACSU/comK/comK-deep-research-falcon.md
  review:
    summary: ComK is the master positive regulator of competence establishment. It
      activates transcription of all late competence genes and also positively regulates
      its own expression through an autoregulatory feedback loop.
    action: NEW
    reason: This term should be added as it specifically captures ComK's regulatory
      role in competence. ComK positively regulates the establishment of competence
      by activating transcription of late competence genes. The positive autoregulation
      at the comK promoter creates a bistable switch that controls entry into the
      competent state. This term complements GO:0030420 by specifying the regulatory
      relationship.
    supported_by:
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: ComK is a DNA-binding transcription activator that triggers
        the K-state (competent state) by upregulating late competence genes required
        for DNA uptake, processing, and recombination; it also activates its own transcription,
        forming a positive feedback loop (autoregulation)
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: Positive feedback at PcomK creates a switch-like, bimodal population
        in which only a subpopulation becomes competent (K-state)
- term:
    id: GO:0000976
    label: transcription cis-regulatory region binding
  evidence_type: TAS
  original_reference_id: file:BACSU/comK/comK-deep-research-falcon.md
  review:
    summary: ComK binds to specific cis-regulatory regions (K-boxes) in promoters
      of competence genes. The K-box is a well-characterized AT-rich motif (AAAA-N5-TTTT)
      that ComK recognizes as a tetramer.
    action: NEW
    reason: This molecular function term captures the specific DNA-binding activity
      of ComK at promoter regulatory regions. ComK binds K-box elements which are
      cis-regulatory regions in promoters of competence genes. This term provides
      more specific information about the nature of ComK's DNA binding activity compared
      to the generic GO:0003677.
    supported_by:
    - reference_id: file:BACSU/comK/comK-deep-research-falcon.md
      supporting_text: "ComK binds promoter K-boxes, typically recognized as a symmetric\
        \ AT-rich motif AAAA\u2013N5\u2013TTTT; ComK forms a dimer-of-dimers (tetramer)\
        \ to bind K-box elements and activate transcription at competence promoters\
        \ including comG and its own comK promoter"
core_functions:
- molecular_function:
    id: GO:0001216
    label: DNA-binding transcription activator activity
  description: Core molecular function - ComK binds K-box motifs as a tetramer to
    activate transcription of late competence genes
  directly_involved_in:
  - id: GO:0045809
    label: positive regulation of establishment of competence for transformation
  - id: GO:0030420
    label: establishment of competence for transformation
proposed_new_terms: []
suggested_questions:
- question: What is the precise molecular mechanism by which ComK tetramer binding
    to K-boxes recruits RNA polymerase and activates transcription? While ComK binding
    to K-boxes is established, the detailed mechanism of transcription activation
    (interaction with sigma factors, RNAP recruitment) is less clear.
- question: Are there ComK-repressed genes beyond rok, and what is the mechanism of
    repression? UniProt notes ComK may repress some genes, but the extent and mechanism
    is unclear.
suggested_experiments:
- description: ChIP-seq of ComK in competent B. subtilis cells to comprehensively
    map K-box binding sites genome-wide. This would provide definitive map of direct
    ComK targets versus indirect effects.
- description: Structural studies of ComK tetramer bound to K-box DNA. This would
    reveal molecular basis for K-box recognition and tetramer assembly.
tags:
- bacsu

comK

Gene Description

Existing Annotations Review

Core Functions

Core molecular function - ComK binds K-box motifs as a tetramer to activate transcription of late competence genes

References

Suggested Questions for Experts

Suggested Experiments

Tags

Deep Research

Falcon

Citations

OpenScientist

AIGR Gene Hypothesis Deep Research — Final Report

ComK (BACSU, UniProt P40396): ATP binding (GO:0005524) computational prediction

Summary

Key Findings

Finding 1 — ComK is a sequence-specific DNA-binding transcription factor with no ATP-binding motif (prediction REFUTED)

Finding 2 — ComK's only genuine ATP connection is as a substrate of the ATP-dependent MecA–ClpCP protease (explains the false positive)

Mechanistic Model / Interpretation

Comparison table: expected features of an ATP-binding protein vs. observed for ComK

Evidence Base / Evidence Matrix

GO Curation Implications

Mechanistic Scope

Conflicts and Alternatives

Limitations and Knowledge Gaps

Discriminating Tests / Proposed Follow-up Experiments

Curation Leads (require curator verification)

Conclusion

Artifacts

📚 Additional Documentation

Bioreason Rl Predictions

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Bioreason Rl Review

BioReason-Pro RL Review: comK (B. subtilis)

Functional Summary Review

Notes on thinking trace

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