pctC (Q9HW93, PA4307) review notes

Review session 2026-11-05 (PseudoCAP IBA-seed protocol, tier 2)

Fetched with just fetch-gene PSEAE Q9HW93 --alias pctC (accession fetch); accession Q9HW93 matches the worklist. Reviewed Swiss-Prot entry. No deep-research provider was used; literature found through the UniProt references and the PubMed MCP, and the cited papers were cached with ai-gene-review fetch-pmid. PMC full text could not be retrieved through the PubMed MCP for the PseudoCAP seed papers with PMC ids (empty body), so those were read as abstracts; the confidence rule is not engaged because no defect is recorded.

Identity

MCP with two TM helices (11-31, 280-300) around a periplasmic dCache_1 ligand binding region, cytoplasmic HAMP and MCPsignal domains (PF02743, PF00672, PF00015; PTHR32089:SF39). LBR structure 5LTV.
Paralogue of PctA, from a pctA duplication in the ancestor of the genus Pseudomonas PMID:31964737.

Literature

Seed paper PMID:9353923 (abstract only).
Direct binding of two amino acids and GABA PMID:23650915; pctC mutant loses GABA taxis PMID:23650915.
Histamine chemotaxis without histamine binding PMID:30425146; full text: pctC in trans restored histamine chemotaxis of the deletion strain.
Repellent role PMID:16233808.

Annotation decisions

Same pattern as pctB (see genes/PSEAE/pctB/pctB-notes.md): chemotaxis, response to amino acid and amino acid binding rows ACCEPT; plasma membrane ACCEPT; membrane TOO_GENERAL; signal transduction MODIFY to GO:0007166; NEW GO:0004888 (IC), core MF.
Action counts: ACCEPT 8, MODIFY 1, TOO_GENERAL 1, NEW 1.

PseudoCAP IBA-seed assessment

Node-level assessment: see genes/PSEAE/pctB/pctB-notes.md (recorded once there); summary repeated below.

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale	other seeds	IBD stands without this seed?
PTN001280296	GO:0006935 chemotaxis	10	215 (22 taxa)	GO:0006935, IMP, PMID:9353923	SOUND	Abstract states complementation of the pct deletion strain by pctC restores His and Pro chemotaxis; pctC mutant later shown to lose GABA taxis, and the LBR binds these ligands.	PctA, PctB/PctC, CtpH, CtpL, CtpM, Aer (PseudoCAP IMP); B. subtilis McpC (IDA/IMP positive chemotaxis); B. subtilis and H. salinarum HemAT (IDA aerotaxis)	Yes; independent IDA seeds (McpC, two HemATs) and six other PseudoCAP seeds

No source_defects were recorded: the PseudoCAP row is sound and the IBD (shared with pctB, ctpH, ctpM, aer, ctpL, pctA) is sound; no GO_CENTRAL defect.