AlgZ (also FimS; PA5262) is the membrane sensor of the AlgZR two-component system. It has four predicted N-terminal transmembrane helices and a cytoplasmic LytS/YpdA-type histidine kinase region. The H box with its phosphorylatable histidine is conserved, but the N box is degenerate and the G1, F and G2 boxes of the ATP lid are missing. Together with its response regulator AlgR, it is needed for twitching motility: AlgR phosphorylation activates the fimU-pilVWXY1Y2E minor pilin operon. AlgZR also coordinates other phenotypes, including cyanide production. The signal AlgZ senses is unknown. This PA5262 protein is distinct from AmrZ (PA3385), the DNA-binding protein first described under the name AlgZ.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000155 phosphorelay sensor kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN002531636, seeded by E. coli YpdA (IMP). AlgZ is the genetically defined kinase partner of AlgR. Reason: The H box (RPHFLFNSL) is conserved, and AlgR phosphorylation in an AlgZ-dependent pathway activates fimU. The missing ATP-lid boxes make AlgZ an atypical kinase whose activity has not been shown biochemically, so this is an accepted inference, not a demonstrated activity. Supporting Evidence: PMID:24999454 Together, these data indicate that AlgR phosphorylation by AlgZ increased AlgR affinity to the fimU promoter and activated its transcription. PMID:24999454 The obvious similarities between AlgZ and canonical histidine kinases are limited to these two boxes, as AlgZ lacks identifiable G1, F, and G2 boxes that make up the ATP-coordinating flexible lid. |
| GO:0000155 phosphorelay sensor kinase activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO from the histidine kinase internal region (PF06580). Reason: Same claim as the IBA row, consistent with the conserved H box. Supporting Evidence: file:PSEAE/algZ/algZ-uniprot.txt Pfam; PF06580; His_kinase |
| GO:0000160 phosphorelay signal transduction system | IDA PMID:8790418 The alginate regulator AlgR and an associated sensor FimS ar... | ACCEPT | Summary: PseudoCAP seed row for PTN002531636 (node term GO:0007165). Whitchurch et al. identified fimS next to algR and showed it is needed for twitching motility. Reason: Seed verdict UNVERIFIABLE. The term is correct: AlgZ is the sensor of the AlgZR two-component system. The IDA code could not be checked, because the PMC copy is a page scan. The abstract describes sequence identification and a mutant phenotype, which would fit IMP or ISS rather than IDA. Deferring to the curator on the term, with a SUSPECTED evidence-code query. Supporting Evidence: PMID:8790418 Adjacent to algR we have identified a sensor gene (fimS), which is also required for twitching motility. PMID:24999454 As described below, twitching motility, requires AlgR and its HK, AlgZ/FimS (Whitchurch et al., 1996). |
| GO:0000160 phosphorelay signal transduction system | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO from the histidine kinase internal region. Reason: Core process of a two-component sensor; same claim as the PseudoCAP row. Supporting Evidence: PMID:24999454 Together, these data indicate that AlgR phosphorylation by AlgZ increased AlgR affinity to the fimU promoter and activated its transcription. |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN002531636, seeded by the membrane sensors YpdA and BtsS. Reason: Four predicted N-terminal TM helices (Phobius) with a cytoplasmic kinase region; a membrane-anchored sensor. Supporting Evidence: file:PSEAE/algZ/algZ-uniprot.txt TRANSMEM 29..47 PMID:24999454 This arrangement is similar to many membrane anchored histidine kinases, and strongly suggests AlgZ is localized to the membrane. |
| GO:0007165 signal transduction | IBA GO_REF:0000033 | TOO GENERAL | Summary: IBA from PTN002531636, seeded by AlgZ itself (expected self-seed, via its GO:0000160 row), YpdA and BtsS. Reason: True. It is entailed by the accepted GO:0000160 phosphorelay signal transduction system, which is_a signal transduction. The IBD stands on the E. coli seeds (see notes). Supporting Evidence: PMID:24999454 As described below, twitching motility, requires AlgR and its HK, AlgZ/FimS (Whitchurch et al., 1996). |
| GO:0016020 membrane | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO membrane. Reason: Correct but general; the protein is in the inner (plasma) membrane, a term it already carries. Proposed replacements: plasma membrane Supporting Evidence: file:PSEAE/algZ/algZ-uniprot.txt TRANSMEM 29..47 |
| GO:2000147 positive regulation of cell motility | IMP PMID:8790418 The alginate regulator AlgR and an associated sensor FimS ar... | KEEP AS NON CORE | Summary: PseudoCAP IMP. The fimS mutant has lost twitching motility. Reason: AlgZR promotes twitching by activating the minor pilin genes through AlgR. The term is as specific as GO allows (there is no "regulation of type IV pilus-dependent motility" term). It is a downstream output of the signalling activity, so non-core. Supporting Evidence: PMID:8790418 Adjacent to algR we have identified a sensor gene (fimS), which is also required for twitching motility. PMID:24999454 Though the signal for the AlgZ sensor kinase has not been determined, the signal, via AlgR phosphorylation, activates twitching motility by increasing the expression of these prepilins. |
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Download this section (compressed HTML)Experiment: Test autophosphorylation of purified or membrane-reconstituted AlgZ and phosphotransfer to AlgR Asp54, and compare H-box histidine mutants for twitching, to see whether AlgZ is a true kinase despite lacking the ATP-lid motifs.
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