XcpW (PA3098, also PddD) is the GspJ-family minor pseudopilin of the Xcp type II secretion system of Pseudomonas aeruginosa, the machine that exports elastase, lipases and other exoproteins from the periplasm across the outer membrane. It is made as a prepilin-like precursor whose short leader is removed by the prepilin peptidase PilD/XcpA, which also N-methylates the new N-terminal phenylalanine; the mature protein is anchored in the inner membrane by its N-terminal helix and has a type IV pilin-like periplasmic domain. XcpW forms with XcpV the core of the pseudopilus tip complex, which also recruits XcpX and XcpU, and is required for type II secretion.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | EXP PMID:8331069 Cleavage, methylation, and localization of the Pseudomonas a... | ACCEPT | Summary: UniProt EXP annotation from Nunn and Lory 1993, who localised XcpT-W to the inner membrane by cell fractionation. Reason: Fractionation of wild-type and pilD mutant cells placed XcpW precursor and mature forms in the inner membrane, which is the plasma membrane of a Gram-negative bacterium. Supporting Evidence: PMID:8331069 the precursor forms of XcpT-W are located predominantly in the bacterial inner membrane, and their localization is not altered after PilD-mediated removal of the leader sequence |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (cell inner membrane) to plasma membrane. Reason: Consistent with the experimental inner-membrane localisation (PMID:8331069). Supporting Evidence: PMID:8331069 the precursor forms of XcpT-W are located predominantly in the bacterial inner membrane |
| GO:0015627 type II protein secretion system complex | IDA PMID:8331069 Cleavage, methylation, and localization of the Pseudomonas a... | ACCEPT | Summary: PseudoCAP IDA from Nunn and Lory 1993 (PilD cleavage, N-methylation and inner-membrane localisation of XcpT-W); sole seed of the GO:0015627 IBD at PTN002446812. Reason: The term is correct. XcpW is a pseudopilin of the Xcp machine and is part of the XcpU-V-W-X pseudopilus tip complex (PMID:19828448) and the crystallised XcpVW and XcpVWX complexes (PMID:30346996). The cited paper, however, as far as its abstract shows, assays processing, methylation and membrane fractionation, not complex membership; it treats XcpW as a component of the apparatus rather than showing it. Full text is not in PMC, so the row is kept, with a suspected-level note that a complex-membership paper (PMID:19828448) would be the better reference. Supporting Evidence: PMID:8331069 Four components of the apparatus of extracellular protein secretion of Pseudomonas aeruginosa, Xcpt, -U, -V, and -W (XcpT-W), are synthesized as precursors with short N-terminal leader peptides PMID:19828448 The assembly of this quaternary complex was further demonstrated by co-purification using affinity chromatography PMID:30346996 we have confirmed that two minor pseudopilins, XcpV and XcpW, constitute a core complex indispensable to the pseudopilus tip |
| GO:0015627 type II protein secretion system complex | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO mapping from the T2SS GspJ family entry IPR010055. Reason: GspJ is a T2SS-specific minor pseudopilin family (NCBIfam TIGR01711); the mapping is correct and is confirmed experimentally for XcpW. Supporting Evidence: file:PSEAE/xcpW/xcpW-uniprot.txt NCBIfam; TIGR01711; gspJ; 1. PMID:19828448 We found an XcpV(I)-W(J)-X(K) complex, which demonstrates that the crystallized trimeric complex also exists in the P. aeruginosa T2SS |
| GO:0015628 protein secretion by the type II secretion system | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA from PTN002218419, with XcpW as WITH/FROM; the PAINT seed file lists the XcpW seed at PTN002446812, so the node identifier differs between the seed data and current GOA. Reason: The claim holds for XcpW (mutant loses LasB secretion, restored by complementation; PMID:30346996) and for GspJ proteins generally. The PseudoCAP seed's evidence code is wrong (IDA on a review) but primary mutant evidence exists, so the IBD is sound. Current QuickGO leaves of PTN002218419 are overwhelmingly GspJ-named. XcpW in its own WITH/FROM reflects its seed and is expected. Supporting Evidence: PMID:30346996 The absence of either XcpV or -W resulted in the non-functional T2SS file:PSEAE/xcpV/xcpV-bioinformatics/RESULTS.md PTN002218419 GO:0015628 (IBA node on XcpW/GspJ in current GOA): 618 proteins; T2SS-named=542, T4P/MSHA/TCP-named=2, generic/other=74 |
| GO:0015628 protein secretion by the type II secretion system | IDA PMID:9818381 GSP-dependent protein secretion in gram-negative bacteria: t... | ACCEPT | Summary: PseudoCAP IDA citing Filloux, Michel and Bally 1998, a review of the Xcp system; sole seed of the GO:0015628 IBD at PTN002446812. Reason: The term is correct (XcpW mutants lose secretion; PMID:1309616, PMID:30346996), but a review with no original secretion data (full text checked) cannot support IDA. The evidence should be TAS for this reference, or the row should be re-keyed to a primary mutant paper (PMID:30346996 or PMID:1309616) as IMP. Recorded consistently with the same defect on XcpX, XcpS and XcpV. Supporting Evidence: PMID:9818381 we will use the P. aeruginosa Xcp system as a basis to discuss multiple aspects of the GSP mechanism PMID:30346996 The absence of either XcpV or -W resulted in the non-functional T2SS |
| GO:0015628 protein secretion by the type II secretion system | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO mapping from the T2SS GspJ family entry IPR010055. Reason: Correct for a T2SS-specific family; consistent with the mutant evidence for XcpW. Supporting Evidence: PMID:30346996 The absence of either XcpV or -W resulted in the non-functional T2SS |
Loading supporting content…
Download this section (compressed HTML)Q: Does the full text of PMID:8331069 contain any assay of XcpW complex membership, or should the PseudoCAP GO:0015627 row be re-keyed to the tip-complex paper PMID:19828448?
Q: Are PTN002446812 (PAINT seed file) and PTN002218419 (current GOA WITH/FROM) the same GspJ node renamed between PANTHER versions?
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)