PA4156 / FvbA (Q9HWM5) notes

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

Fetched with just fetch-gene PSEAE Q9HWM5 --alias PA4156 (accession fetch). Accession
Q9HWM5 (unreviewed, PE3) matches the worklist. No deep-research keys; literature from the
cached seed paper (PMID:21546589, abstract-only) and the UniProt record.

Identity

TonB-dependent outer-membrane receptor. Signal peptide 1-29, plug 56-171, beta-barrel
270-658. Pfam Plug + TonB_dep_Rec_b-barrel. UniProt places it in PANTHER PTHR32552
(ferrichrome iron receptor-related); PAINT seeded the GO:0015344 IBD at PTN004738955
(PTHR30069). Close homologue of the V. cholerae vibriobactin receptor ViuA.

Literature

FvbA required for vibriobactin use
PMID:21546589;
PMID:21546589.
Fur- and FvbR-regulated (described as preliminary)
PMID:21546589.

Annotation decisions

Cell outer membrane (IBA, IEA): ACCEPT. Siderophore uptake transmembrane transporter
activity (IBA, IMP): ACCEPT core. Siderophore-iron import into cell (IEA): ACCEPT.
Siderophore transmembrane transport (IBA): ACCEPT core process.
Siderophore transport (IMP, GO:0015891): TOO_GENERAL (GO:0044718 is its is_a descendant).
Cellular response to iron ion (EXP, GO:0071281, CollecTF, PMID:21546589):
MARK_AS_OVER_ANNOTATED. The evidence is that fvbA expression is Fur/vibriobactin/FvbR
controlled, i.e. fvbA is a Fur target, not a participant in the iron response; iron-regulated
expression of a target gene is not a role in responding to iron (Fur itself carries the
term). Abstract calls the regulation analysis preliminary.
Action counts: ACCEPT 5, TOO_GENERAL 1, MARK_AS_OVER_ANNOTATED 1.
No source defect on the PseudoCAP seed (sound). The GO:0071281 row is CollecTF, not
PseudoCAP; handled by MARK_AS_OVER_ANNOTATED rather than a source defect.

PseudoCAP IBA-seed assessment

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale	other seeds	IBD stands without this seed?
PTN004738955	GO:0015344 siderophore uptake transmembrane transporter activity	4	142 (21 taxa)	GO:0015344, IMP, PMID:21546589	SOUND	fvbA mutant (in a pvd/pch-null background) cannot use vibriobactin; FvbA is homologous to the V. cholerae vibriobactin receptor ViuA. Direct genetic evidence for ferric-siderophore uptake.	PfeA (Q05098), ChtA (PA4675, Q9HVC0), PirA (Q9I527) — PseudoCAP IMP; E. coli CirA (P17315) at the partner process IBD	Yes

The node-level assessment of PTN004738955 is recorded once in PA4675-notes.md (IBD sound,
node term suits the clade, no GO_CENTRAL defect). FvbA is consistent with it.