ComGA is an AAA+ ATPase that powers the assembly of the ComG competence pseudopilus in Bacillus subtilis. The protein contains a P-loop NTPase domain homologous to type II secretion system ATPases (GspE/T2SS-E family). ComGA is essential for DNA binding at the cell surface during natural genetic transformation, as it drives the assembly of competence pili composed primarily of ComGC pilin subunits. The protein localizes to cell poles through diffusion-capture mediated by ComEB, where it forms foci coincident with the DNA uptake machinery. ATP hydrolysis by ComGA is required for function, as Walker B motif mutations abolish both DNA binding and transformation competence while still allowing polar localization. During competence development, ComGA dynamics increase upon addition of extracellular DNA, consistent with pilus activity during substrate engagement.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: ComGA localizes to the cytoplasmic side of the cell membrane as a peripheral membrane protein, with enrichment at cell poles during competence development. The protein accumulates at cell poles through diffusion-capture and forms discrete foci coincident with the DNA uptake machinery. Reason: The IBA annotation is well-supported by experimental evidence. UniProt annotates ComGA as a peripheral membrane protein on the cytoplasmic side of the cell membrane based on PMID:9723928. Recent studies demonstrate polar membrane localization during competence. While ComGA also localizes more specifically to cell poles (GO:0060187), the plasma membrane annotation captures the essential cellular location. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA accumulates at a single cell pole through diffusion-capture, recruited by ComEB; DNA addition increases ComGA turnover and enhances polar localization |
| GO:0016887 ATP hydrolysis activity | IBA GO_REF:0000033 | ACCEPT | Summary: ComGA is an AAA+ ATPase with functional Walker A/B motifs that powers competence pilus assembly. ATP hydrolysis is required for DNA binding and transformation function, as Walker B motif mutations abolish DNA binding activity while still permitting polar localization. Reason: This annotation is strongly supported by both sequence analysis (P-loop NTPase domain, Walker A/B motifs) and functional studies. ComGA belongs to the GSP E family of secretion ATPases. Mutagenesis studies demonstrate that ATP hydrolysis is essential for function in DNA uptake. The IBA annotation correctly captures the core molecular function. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA is an AAA+ ATPase that powers ComG pseudopilus assembly, a requirement for DNA binding at the cell surface and for subsequent uptake. Mutation of the Walker B motif abrogates DNA binding, implicating ATP hydrolysis in function |
| GO:0000166 nucleotide binding | IEA GO_REF:0000043 | ACCEPT | Summary: ComGA contains a P-loop NTPase domain with Walker A/B motifs that bind ATP. The protein has a predicted ATP binding site at residues 144-151. Reason: This IEA annotation from UniProt keyword mapping is correct but redundant with the more specific ATP binding annotation (GO:0005524). ComGA clearly binds nucleotides (specifically ATP) based on domain analysis and functional requirements. Accept as a valid but less informative parent term. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA is an AAA+ P-loop NTPase homologous to type II secretion ATPases (GspE/T2SS-E). Functional Walker A/B motifs are present, and ATP hydrolysis is required for DNA binding and competence function |
| GO:0005524 ATP binding | IEA GO_REF:0000043 | ACCEPT | Summary: ComGA binds ATP through its P-loop NTPase domain. UniProt annotates a specific ATP binding site at residues 144-151 containing the Walker A motif. Mutagenesis of the Walker A lysine (K150Q) abolishes transformation while preserving polar localization. Reason: This annotation is well-supported by domain analysis showing Walker A/B motifs characteristic of AAA+ ATPases, and by functional evidence that ATP binding/hydrolysis is essential for ComGA function. The ATP binding annotation complements the ATP hydrolysis activity annotation and is appropriately specific. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA is an AAA+ P-loop NTPase homologous to type II secretion ATPases (GspE/T2SS-E). Functional Walker A/B motifs are present |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: ComGA is a peripheral membrane protein localized to the cytoplasmic side of the cell membrane. This IEA annotation derived from UniProt subcellular location vocabulary is consistent with experimental evidence showing membrane association. Reason: This annotation duplicates the IBA annotation for the same term but with different evidence. Both are correct. UniProt subcellular location curation confirms membrane localization based on experimental literature. Accept as valid supporting evidence for membrane localization. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA accumulates at a single cell pole through diffusion-capture, recruited by ComEB |
| GO:0030420 establishment of competence for transformation | IEA GO_REF:0000043 | ACCEPT | Summary: ComGA is essential for natural genetic transformation in B. subtilis. It powers the assembly of competence pili required for DNA binding and uptake at the cell surface. Deletion of comGA abolishes transformation and eliminates surface-exposed pilus structures. Reason: This annotation accurately captures the core biological process in which ComGA functions. ComGA is expressed specifically in competent cells (5-15% of population) under ComK regulation, and is absolutely required for DNA uptake during natural transformation. The term appropriately describes the process-level function of the protein. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md Deletion of comGA abolishes surface-exposed pilus structures and transformation-associated DNA binding/uptake PMID:11918817 In Bacillus subtilis, the competence transcription factor ComK activates its own transcription as well as the transcription of genes that encode DNA transport proteins PMID:11948146 The Bacillus subtilis competence transcription factor ComK is required for establishment of competence for genetic transformation |
| GO:0060187 cell pole | IDA file:BACSU/comGA/comGA-deep-research-falcon.md | NEW | Summary: ComGA localizes to cell poles during competence development through diffusion-capture mediated by ComEB. The protein forms discrete foci at cell poles coincident with the DNA uptake machinery. Reason: Cell pole localization is a well-characterized feature of ComGA that is more specific than plasma membrane. Multiple studies demonstrate polar localization during competence, with dynamics increasing upon DNA addition. This annotation adds precision to the cellular location without conflicting with the broader plasma membrane annotation. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md ComGA accumulates at a single cell pole through diffusion-capture, recruited by ComEB; DNA addition increases ComGA turnover and enhances polar localization |
| GO:0009297 pilus assembly | IDA file:BACSU/comGA/comGA-deep-research-falcon.md | NEW | Summary: ComGA powers the assembly of competence pili (ComG pseudopilus) from ComGC pilin subunits. Deletion of comGA abolishes surface-exposed pilus structures. Reason: Pilus assembly is the direct biochemical function through which ComGA enables competence. The protein provides ATP hydrolysis energy for pseudopilus biogenesis. This annotation links the molecular function (ATP hydrolysis) to the specific cellular assembly process. Supporting Evidence: file:BACSU/comGA/comGA-deep-research-falcon.md Deletion of comGA abolishes surface-exposed pilus structures and transformation-associated DNA binding/uptake |
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)