PA0938 (Wzz2) is the second O-antigen chain-length regulator of Pseudomonas aeruginosa PAO1, encoded outside the B-band O-antigen cluster. It is a 442-residue inner-membrane polysaccharide co-polymerase of the PCP-1 class, with two transmembrane helices flanking a large periplasmic domain and no cytoplasmic kinase domain; it groups with E. coli FepE, which makes very long O-antigen. Together with Wzz1 (PA3160) and the Wzy polymerase, Wzz2 sets the modal chain length of B-band O-specific antigen before it is ligated to lipid A-core: deletion of wzz2 leaves the Wzz1-specified modality, and deletion of both genes gives non-modal chains. Wzz2 forms octamers in vivo and co-precipitates with O-antigen polymer.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000794252 (five seeds: Wzz2 itself, Wzz1, E. coli FepE, Wzc and Etk). Reason: Two predicted TM helices and the PCP topology place Wzz2 in the inner membrane; three E. coli seeds have direct plasma-membrane evidence, so the node term holds for the clade. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 28..49 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" |
| GO:0004713 protein tyrosine kinase activity | IBA GO_REF:0000033 | REMOVE | Summary: IBA from PTN000794252, seeded by the E. coli BY-kinases Etk and Wzc. Wzz2 is a PCP-1 co-polymerase with no kinase domain. Reason: Wzz2 ends 30 residues after its second TM helix and lacks the cytoplasmic Walker A/B tyrosine-autokinase domain of Wzc and Etk; its GNVR motif is a shared periplasmic/TM2-junction motif, not the catalytic domain. The node-level defect is recorded once, on wzz (PA3160). Propagation Review Root cause: PROPAGATION BAD Failure modes: WRONG ORTHOLOG OR PARALOG FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN000794252 Β· PTN000794252 SUPPORTS SOURCE BUT NOT TARGET Mixed node containing BY-kinases (Wzc, Etk) and kinase-less PCP-1 chain-length regulators (Wzz1, Wzz2, FepE). GO_CENTRAL defect recorded on wzz (PA3160). UniProtKB:P76387 Β· E. coli Wzc SUPPORTS SOURCE BUT NOT TARGET True BY-kinase; its activity resides in the cytoplasmic domain Wzz2 lacks. UniProtKB:P38134 Β· E. coli Etk SUPPORTS SOURCE BUT NOT TARGET True BY-kinase; its activity resides in the cytoplasmic domain Wzz2 lacks. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 392..412 FT /note="Helical" PMID:12534470 As expected, the wzz2delta strain produced LPS with modal length imparted by Wzz1, and the wzz2delta/wzz1::Gm strain produced LPS O-antigen with a non-modal (random) length. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Mapping of the UniProt location (cell membrane, multi-pass). Reason: Same claim as the accepted IBA, supported by the two predicted TM helices. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 28..49 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" |
| GO:0016020 membrane | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro2GO mapping of the Wzz N-terminal domain. Reason: True, but entailed by the accepted GO:0005886 plasma membrane, which is_a membrane. |
| GO:0005886 plasma membrane | IDA PMID:12534470 Pseudomonas aeruginosa O-antigen chain length is determined ... | ACCEPT | Summary: PseudoCAP row and a seed of PTN000794252. The location is right; the abstract does not describe how it was determined. Reason: Two TM helices and the PCP-1 topology support the inner-membrane location. The full text may contain a fractionation with the anti-Wzz2 antibodies the paper raised, so the IDA code is not challenged. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 392..412 FT /note="Helical" |
| GO:0005886 plasma membrane | IDA PMID:23955007 The D3 bacteriophage Ξ±-polymerase inhibitor (Iap) peptide di... | ACCEPT | Summary: PseudoCAP row and a seed of PTN000794252. The abstract reports sequence alignment of Iap with the Wzz TM1 and topology predictions of Iap, not a localisation assay of Wzz2. Reason: The location is right. The evidence behind this row looks like sequence analysis rather than a direct assay, recorded as a suspected evidence-code defect since only the abstract was read. Supporting Evidence: PMID:23955007 Sequence alignment analyses revealed a high degree of similarity between Iap and the first transmembrane segment (TMS) of either Wzz1 or Wzz2. |
| GO:0009243 O antigen biosynthetic process | EXP PMID:12534470 Pseudomonas aeruginosa O-antigen chain length is determined ... | ACCEPT | Summary: PseudoCAP row. wzz2 and wzz1 wzz2 mutants alter O-antigen chain-length modality. Reason: Wzz2 acts with Wzy in O-antigen polymerisation to set modal chain length, so it takes part in O-antigen synthesis. Supporting Evidence: PMID:12534470 As expected, the wzz2delta strain produced LPS with modal length imparted by Wzz1, and the wzz2delta/wzz1::Gm strain produced LPS O-antigen with a non-modal (random) length. |
| GO:0009276 Gram-negative-bacterium-type cell wall | IDA PMID:24309320 Conserved-residue mutations in Wzy affect O-antigen polymeri... | REMOVE | Summary: PseudoCAP row. GO:0009276 is the peptidoglycan layer of the Gram-negative envelope; the cited paper (full text read) reports no localisation of Wzz2 to it. Reason: Wzz2 is an integral inner-membrane protein (two TM helices), and the paper is a Wzy mutagenesis study in which Wzz2 serves only as a modality readout and mCherry-fusion complementation construct. No assay in the text places Wzz2 in the peptidoglycan layer. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 392..412 FT /note="Helical" PMID:24309320 regulation of polymer length is affected by interaction of Wzz with Wzy |
| GO:0016020 membrane | IDA PMID:23955007 The D3 bacteriophage Ξ±-polymerase inhibitor (Iap) peptide di... | TOO GENERAL | Summary: PseudoCAP row from the Iap mimicry paper. Reason: True, but entailed by the accepted GO:0005886 plasma membrane. The evidence-code doubt recorded on the plasma-membrane row from the same paper applies here too. |
| GO:0043165 Gram-negative-bacterium-type cell outer membrane assembly | IDA PMID:12534470 Pseudomonas aeruginosa O-antigen chain length is determined ... | MARK AS OVER ANNOTATED | Summary: PseudoCAP row. The paper studies O-antigen chain length, not outer membrane assembly. Reason: Wzz2 regulates the length of O-antigen made at the inner membrane; the finished LPS is moved to the outer membrane by the Lpt machinery. Making a component of the outer membrane is not assembling it. Same judgement as for wzz (PA3160). Supporting Evidence: PMID:12534470 As expected, the wzz2delta strain produced LPS with modal length imparted by Wzz1, and the wzz2delta/wzz1::Gm strain produced LPS O-antigen with a non-modal (random) length. |
| GO:0043165 Gram-negative-bacterium-type cell outer membrane assembly | IDA PMID:24309320 Conserved-residue mutations in Wzy affect O-antigen polymeri... | MARK AS OVER ANNOTATED | Summary: PseudoCAP row from a Wzy mutagenesis study in which Wzz2 modality is a readout. Reason: The full text reports O-antigen modality and Wzy stability, not outer membrane assembly. Supporting Evidence: PMID:24309320 regulation of polymer length is affected by interaction of Wzz with Wzy |
| GO:0098567 periplasmic side of plasma membrane | IDA PMID:12534470 Pseudomonas aeruginosa O-antigen chain length is determined ... | ACCEPT | Summary: PseudoCAP row and a seed of the PTN000794252 plasma-membrane IBD (GO:0098567 is part_of plasma membrane). The bulk of Wzz2, its periplasmic domain, lies on this side. Reason: Right for a PCP-1 protein, and GO:0098567 includes membrane-embedded proteins. The abstract does not describe a topology assay; no defect is filed because the full text may contain one. Supporting Evidence: file:PSEAE/PA0938/PA0938-uniprot.txt TRANSMEM 28..49 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" |
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Download this section (compressed HTML)Q: What modal length does Wzz2 specify on its own (very long, like FepE?), and does it interact with Wzy through a different surface from Wzz1, given that Wzy CL6 mutations spare Wzz2 modality?
Experiment: Chain-length analysis of a wzz1 mutant expressing Wzz2 alone, and crosslinking or co-purification of Wzz2 with Wzy carrying CL6 substitutions.
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