pfeA (PA2688, Q05098) notes

Identity

Ferric enterobactin receptor PfeA, 746 aa, Swiss-Prot. TonB-dependent outer
membrane receptor (TBDR): signal peptide 1-25, TonB box 39-44, plug domain
47-174, 22-strand beta-barrel 179-746, TonB C-terminal box 729-746. FepA
ortholog (>60% identity to E. coli FepA). PANTHER PTHR30069:SF51
"FERRIENTEROBACTIN RECEPTOR"; TCDB 1.B.14.1.5.
No N-terminal signalling extension before the TonB box (signal peptide ends at
25, TonB box at 39): PfeA is a receptor/transporter, not a TonB-dependent
transducer like FpvA. Enterobactin sensing for pfeA induction is done by the
separate PfeS/PfeR two-component system (not reviewed here).
No deep-research provider was available; notes are from cached publications.

Literature

PseudoCAP seed paper (Dean and Poole 1993, abstract only; PMC196144 full text not
retrievable): mutant K407 lacking the 80 kDa receptor grows poorly on
enterobactin under iron limitation
PMID:8419284;
the cloned gene restores enterobactin-dependent iron uptake in E. coli fepA
PMID:8419284;
the product is made in outer membranes
PMID:8419284.
PirA (PA0931) is a second ferric-enterobactin receptor; only the pfeA pirA
double mutant fails to use ferric enterobactin
PMID:15899402.
Fluorescent-sensor binding study (UniProt IDA for enterobactin binding)
PMID:35101443.

PseudoCAP IBA-seed assessment

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale
PTN004738955	GO:0015344 siderophore uptake transmembrane transporter activity	4 (PfeA + 3 other PAO1 TBDRs)	142 (21 taxa)	GO:0015344, IMP, PMID:8419284 (PseudoCAP)	SOUND	Loss of the receptor impairs growth on ferric enterobactin, and the cloned gene restores enterobactin-dependent 55Fe uptake in an E. coli fepA mutant: direct genetic evidence that PfeA transports a ferric siderophore across the outer membrane. The node is a large TBDR clade where siderophore uptake is the expected function (a NOT IRD already blocks one child, PTN004739012).
PTN000763909	GO:0042930 enterobactin transport	1 (sole seed)	3 (3 taxa)	GO:0042930, IMP, PMID:8419284 (PseudoCAP)	SOUND	Same evidence; the node holds only the FepA/PfeA ferric-enterobactin receptors (E. coli P05825, Salmonella Q8ZR40, PfeA), for which enterobactin transport is the canonical, experimentally established function.
PTN000763909	GO:0042931 enterobactin transmembrane transporter activity	1 (sole seed)	3 (3 taxa)	GO:0042931, IMP, PMID:8419284 (PseudoCAP)	SOUND	As above. GO:0015620 ferric-enterobactin transmembrane transporter activity would name the iron-loaded substrate more exactly, but GO:0042931 sits under siderophore-iron transmembrane transporter activity and is acceptable.

Not a seed, but noted: the GO:0042912 colicin transmembrane transporter activity
IBA at PTN000763909 (seeded by E. coli FepA, a colicin B/D receptor) is propagated
to PfeA without evidence; P. aeruginosa is not a colicin target in the literature
reviewed. Marked over-annotated (with the inferred bacteriocin transport row).

Decisions summary

ACCEPT: cell outer membrane (IBA, IEA), enterobactin transport (IBA, IMP),
siderophore transmembrane transport (IBA), siderophore uptake transmembrane
transporter activity (IBA, IEA, IMP), enterobactin transmembrane transporter
activity (IBA, IEA, IMP).
MODIFY: siderophore-iron transmembrane transporter activity (IEA) -> enterobactin
transmembrane transporter activity; siderophore transport (IEA, IMP) ->
enterobactin transport; siderophore-iron import into cell (IEA) ->
ferric-enterobactin import into cell; outer membrane (IDA) -> cell outer
membrane.
MARK_AS_OVER_ANNOTATED: colicin transmembrane transporter activity (IBA),
bacteriocin transport (IEA).
REMOVE: signaling receptor activity (IEA, InterPro2GO).
KEEP_AS_NON_CORE: enterobactin binding (IDA).
No PSEUDOCAP defect; GO_CENTRAL CHECK (SUSPECTED) for the colicin IBD reaching PfeA.

PANTHER tree check (2026-11-05)

Topology fetched with projects/PSEUDOCAP/panther_tree.py node PTN000763909 --depth 3 --leaves (PTHR30069). The node is a Gammaproteobacteria SPECIATION node, 3 leaves, all
PTHR30069:SF51.

Child node	Event / taxon	Leaves	Subfamilies	Verdict
PTN002409317	LEAF, P. aeruginosa	1 (Q05098 PfeA)	SF51	Ferric-enterobactin receptor; no colicin evidence
PTN002012591	SPECIATION, Enterobacteriaceae	2 (P05825 E. coli FepA, Q8ZR40 S. typhimurium FepA)	SF51:2	Colicin B/D receptors; correct home for the GO:0042912 IBD

The topology settles the earlier concern cleanly. The node's only non-enterobacterial
leaf is PfeA itself, and the two colicin-receptor leaves form a single child clade, so
GO:0042912 colicin transmembrane transporter activity can be moved from PTN000763909 to
PTN002012591 with no loss: the FepA IBAs survive and the PfeA IBA (reviewed here as
MARK_AS_OVER_ANNOTATED, unchanged) disappears. No NOT annotation is needed. The
GO:0042930 enterobactin transport IBD is right where it is: all three leaves are
ferric-enterobactin receptors. The GO_CENTRAL defect is kept and raised SUSPECTED ->
CONFIRMED, now naming PTN002012591 as the target node.