PA3697 encodes an uncharacterised 431-residue protein of Pseudomonas aeruginosa with a MATCAP (DUF1704) domain and a QEGLA motif (TIGR02421). The domain is named after the animal microtubule-associated tyrosine carboxypeptidase, a metalloprotease; the bacterial members have no demonstrated activity. In P. aeruginosa PAO1 it was isolated with the fhp-fhpR intergenic promoter region as bait. PA3697 mutants lose nitrate- and nitrite-induced activity of the promoter of the flavohemoglobin gene fhp, which encodes an NO-detoxifying enzyme. Its mutants also lose ROS-induced fhp promoter activity, so PA3697 is needed alongside FhpR and PA0779 for full fhp expression. Whether it binds DNA, acts as a protease or works indirectly is unknown.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0080164 regulation of nitric oxide metabolic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from PTN002422332, whose IBD has one seed, this gene's PseudoCAP IMP to PMID:18043907. The worklist counts 5 leaf IBAs; current GOA has about 175 rows citing the node, including dozens of Legionella spp. and planctomycete and myxobacterial proteins. Reason: The seed is a promoter-reporter phenotype. PA3697 mutants lose induced activity of the flavohemoglobin (fhp) promoter, but NO metabolism was not measured and how PA3697 acts is unknown. That phenotype depends on the P. aeruginosa Fhp/FhpR circuit and is not an activity of the MATCAP/QEGLA domain that the clade could inherit. Projecting it to a broad bacterial node with no other experimental member is unsupported. For this gene the claim is kept only as an over-annotation, consistent with the IMP row. Propagation Review Root cause: SOURCE WEAK OR INFERRED Failure modes: SOURCE EVIDENCE WEAK CONTEXT OR TISSUE MISMATCH Sources checked: UniProtKB:Q9HXU3 · PA3697 SOURCE WEAK OR INFERRED Sole seed; PseudoCAP IMP to PMID:18043907, a mutant promoter-activity phenotype on fhp, not a measurement of NO metabolism or a defined regulatory activity. Supporting Evidence: PMID:18043907 Both PA0779 and PA3697 were found to be essential for NO3(-) and NO2(-) induced Pfhp activity under aerobic and low-oxygen conditions file:PSEAE/PA3697/PA3697-uniprot.txt PE 4: Predicted; |
| GO:0080164 regulation of nitric oxide metabolic process | IMP PMID:18043907 Transcriptional activity of Pseudomonas aeruginosa fhp promo... | MARK AS OVER ANNOTATED | Summary: PseudoCAP IMP; sole seed of the PTN002422332 IBD. Koskenkorva et al. (2008) isolated PA3697 with the fhp-fhpR promoter as bait and found it essential for nitrate- and nitrite-induced fhp promoter activity. Reason: The mutant phenotype is real and specific to this gene, but the abstract measures promoter activity of fhp, not nitric oxide metabolism. The link to NO metabolism is two steps removed (fhp transcription, then Fhp-catalysed NO detoxification) and was not tested. The abstract itself shows the claim is an inferred consequence of a reporter phenotype, so the row is marked as over-annotated rather than undecided. A more literal transcription-regulation term is not proposed: there is no evidence that PA3697 binds DNA or acts directly on the promoter. Supporting Evidence: PMID:18043907 Both PA0779 and PA3697 were found to be essential for NO3(-) and NO2(-) induced Pfhp activity under aerobic and low-oxygen conditions, and needed for the full function of Pfhp/PfhpR as NO responsive regulatory circuit under aerobic conditions. PMID:19767835 ROS-induced fhp promoter activity was dependent on FhpR, PA0779, and PA3697 regulators. |
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Download this section (compressed HTML)Q: Does PA3697 bind the fhp-fhpR intergenic region directly, or was it co-isolated through another protein? Its MATCAP domain suggests a metalloprotease rather than a DNA-binding regulator.
Q: Do bacterial MATCAP/QEGLA-domain proteins have peptidase activity, and if so what are their substrates?
Experiment: Purify PA3697 and test (i) specific binding to the fhp-fhpR intergenic DNA by EMSA with competitor DNA, and (ii) zinc-dependent peptidase activity on peptide libraries; in parallel, measure NO consumption by wild-type and PA3697 mutant cells exposed to nitrite or NO donors.
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