CheZ (PA1457) is the CheY-P phosphatase of the main flagellar chemotaxis system of Pseudomonas aeruginosa. By similarity to E. coli CheZ it is a cytoplasmic homodimer that accelerates the dephosphorylation of phosphorylated CheY, so terminating the signal that CheY-P sends to the flagellar motor to switch rotation. It thereby sets the rate at which a swimming cell changes direction and lets the chemotaxis pathway respond quickly to changes in attractant and repellent levels. A cheZ insertion mutant of PAO1 reverses its swimming direction much more often than wild type, the opposite of cheY mutants, and a cheY cheZ mutant is non-chemotactic.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: Root-level catalytic activity from the CheZ InterPro entry. Reason: GO:0004721 phosphoprotein phosphatase activity, accepted here, entails it. |
| GO:0004721 phosphoprotein phosphatase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA seeded by E. coli CheZ, the characterized CheY-P phosphatase. PA1457 is a CheZ-family protein in the same clade; GO has no more specific term for a phospho-aspartate response-regulator phosphatase. Reason: Core molecular function inherited from a well-characterized orthologue. Supporting Evidence: file:PSEAE/cheZ/cheZ-uniprot.txt Plays an important role in bacterial chemotaxis signal transduction pathway by accelerating the dephosphorylation of phosphorylated CheY (CheY-P). |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Soluble protein with no signal peptide or transmembrane segment, acting on cytoplasmic CheY-P. Reason: Consistent with its substrate and with the E. coli orthologue. Supporting Evidence: file:PSEAE/cheZ/cheZ-uniprot.txt Plays an important role in bacterial chemotaxis signal transduction pathway by accelerating the dephosphorylation of phosphorylated CheY (CheY-P). |
| GO:0006935 chemotaxis | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN001098776, seeded by E. coli CheZ, B. subtilis CheC and this gene's own IMP (self-seed, expected). Each seed has experimental chemotaxis evidence. Reason: Sound IBD on a CheY-P phosphatase clade; core process. Supporting Evidence: PMID:7860605 A chromosomal cheZ mutant, constructed by inserting a kanamycin resistance gene cassette into the wild-type gene, changed its swimming direction much more frequently than did wild-type strain PAO1. |
| GO:0006935 chemotaxis | IMP PMID:7860605 Isolation and characterization of chemotaxis mutants and gen... | ACCEPT | Summary: PseudoCAP seed of PTN001098776. The cheZ mutant has an altered swimming-reversal frequency, and the cheY cheZ mutant fails capillary chemotaxis assays. Reason: Direct genetic evidence for a role in chemotactic signalling. Supporting Evidence: PMID:7860605 A chromosomal cheZ mutant, constructed by inserting a kanamycin resistance gene cassette into the wild-type gene, changed its swimming direction much more frequently than did wild-type strain PAO1. |
| GO:0009288 bacterial-type flagellum | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: InterPro2GO mapping. CheZ is a soluble phosphatase acting on CheY-P; it is not a structural part of the flagellum, and no localization to the flagellum has been reported for PA1457. Reason: The mapping conflates the chemotaxis signalling pathway with the organelle it controls. Supporting Evidence: file:PSEAE/cheZ/cheZ-uniprot.txt Plays an important role in bacterial chemotaxis signal transduction pathway by accelerating the dephosphorylation of phosphorylated CheY (CheY-P). |
| GO:0050920 regulation of chemotaxis | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: By terminating CheY-P signalling CheZ tunes chemotactic behaviour, which can be read as regulation; the accepted term is chemotaxis itself. Reason: Defensible but secondary to the accepted chemotaxis annotation. Supporting Evidence: PMID:7860605 A chromosomal cheZ mutant, constructed by inserting a kanamycin resistance gene cassette into the wild-type gene, changed its swimming direction much more frequently than did wild-type strain PAO1. |
| GO:0071978 bacterial-type flagellum-dependent swarming motility | IMP PMID:7860605 Isolation and characterization of chemotaxis mutants and gen... | REMOVE | Summary: The swarm-plate screen in this paper is the soft-agar chemotaxis assay; the mutants were fully motile but did not spread, which the authors attribute to defective chemotactic signalling. No surface-swarming phenotype is reported for the cheZ single mutant. Reason: Term confusion between chemotactic swarm-plate spreading and flagellum-dependent surface swarming. The phenotype is already captured by the chemotaxis row. Supporting Evidence: PMID:7860605 These mutants were fully motile but incapable of swarming, suggesting that they had a defect in the intracellular signalling pathway. |
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Download this section (compressed HTML)Q: P. aeruginosa has several chemotaxis systems and CheY paralogues. Which CheY proteins does PA1457 CheZ dephosphorylate, and does it localize to the polar chemoreceptor array as E. coli CheZ does?
Experiment: Measure CheY-P dephosphorylation by purified PA1457 in vitro, and image a fluorescent CheZ fusion to test polar localization.
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