KinB (PA5484) is the membrane-bound sensor histidine kinase of the KinB-AlgB two-component system of Pseudomonas aeruginosa, encoded immediately downstream of its cognate NtrC-family response regulator AlgB. It is an inner-membrane protein with an N-terminal periplasmic sensor domain, a HAMP linker, a PAS domain and a C-terminal HisKA/HATPase kinase core with the conserved autophosphorylated histidine (His385). The purified cytoplasmic domain autophosphorylates and transfers phosphate to AlgB, and it also dephosphorylates phospho-AlgB. In vivo its phosphatase activity is the dominant output: by keeping AlgB unphosphorylated, KinB limits AlgU (sigma-22) activity, promotes acute-virulence traits (pyocyanin, elastase, motility) and restrains alginate production (mucoidy).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000155 phosphorelay sensor kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the PTN001293174 IBD (seeds E. coli EnvZ P0AEJ4, this gene, and ParS Q9I2U4). KinB has a canonical HisKA/HATPase core and is a demonstrated autokinase that phosphorylates AlgB. Reason: Core activity, consistent with this gene's own experimental evidence; its self-appearance in the With/From is expected. Supporting Evidence: PMID:9218420 COOH-terminal KinB protein was observed to undergo progressive |
| GO:0000155 phosphorelay sensor kinase activity | IDA PMID:9218420 Identification of the histidine protein kinase KinB in Pseud... | ACCEPT | Summary: PseudoCAP IDA and one of three seeds of the PTN001293174 IBD. The abstract reports autophosphorylation of purified C-terminal KinB and rapid phosphotransfer to purified AlgB, lost on substitution of conserved residues. Reason: Sound seed; direct biochemical evidence for sensor kinase activity. Supporting Evidence: PMID:9218420 COOH-terminal KinB protein was observed to undergo progressive PMID:9218420 rapidly transferred to purified AlgB. Substitutions of the residues conserved |
| GO:0000155 phosphorelay sensor kinase activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO from the HisKA dimerisation/phosphoacceptor domain. Reason: Agrees with the experimental evidence. Supporting Evidence: PMID:9218420 COOH-terminal KinB protein was observed to undergo progressive |
| GO:0000160 phosphorelay signal transduction system | IEA GO_REF:0000108 | ACCEPT | Summary: Inferred from the sensor kinase MF. KinB acts in the KinB-AlgB phosphorelay. Reason: KinB phosphorylates and dephosphorylates its cognate regulator AlgB, the defining steps of the two-component phosphorelay. Supporting Evidence: PMID:9218420 rapidly transferred to purified AlgB. Substitutions of the residues conserved PMID:23024348 Together, these data argue that KinB exhibits phosphatase activity and can directly dephosphorylate AlgB. |
| GO:0004673 protein histidine kinase activity | IEA GO_REF:0000120 | TOO GENERAL | Summary: Protein histidine kinase activity from ARBA/EC 2.7.13.3. Reason: True, but phosphorelay sensor kinase activity (GO:0000155), accepted here, is_a this term. |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA plasma membrane from PTN001293174 (seeds EnvZ and P18392). Reason: KinB is an inner-membrane protein with a periplasmic N-terminal domain, shown by phoA fusions; the bacterial inner membrane is the plasma membrane. Supporting Evidence: PMID:9218420 indicate that KinB localizes to the inner membrane and has a NH2-terminal |
| GO:0005886 plasma membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Plasma membrane from UniProt subcellular location mapping. Reason: Consistent with the phoA-fusion topology data. Supporting Evidence: PMID:9218420 indicate that KinB localizes to the inner membrane and has a NH2-terminal |
| GO:0007165 signal transduction | IEA GO_REF:0000002 | TOO GENERAL | Summary: Signal transduction from HAMP/HisKA InterPro entries. Reason: Phosphorelay signal transduction system (GO:0000160), accepted here, is_a signal transduction. |
| GO:0016020 membrane | IEA GO_REF:0000002 | TOO GENERAL | Summary: Membrane from the HAMP domain InterPro entry. Reason: Plasma membrane (GO:0005886), accepted here, is_a membrane. |
| GO:0016301 kinase activity | IEA GO_REF:0000104 | TOO GENERAL | Summary: Kinase activity from UniRule. Reason: Entailed by phosphorelay sensor kinase activity (GO:0000155), accepted here. |
| GO:0016740 transferase activity | IEA GO_REF:0000104 | TOO GENERAL | Summary: Transferase activity from UniRule. Reason: Entailed by phosphorelay sensor kinase activity (GO:0000155), accepted here. |
| GO:0016772 transferase activity, transferring phosphorus-containing groups | IEA GO_REF:0000002 | TOO GENERAL | Summary: Transferase activity, transferring phosphorus-containing groups, from InterPro. Reason: Entailed by phosphorelay sensor kinase activity (GO:0000155), accepted here. |
| GO:0016791 phosphatase activity | IDA PMID:23024348 The two-component sensor KinB acts as a phosphatase to regul... | MODIFY | Summary: PseudoCAP IDA. Full text shows purified HC-KinB removes the label from phospho-AlgB, whereas the P390S mutant does not; adding wild-type KinB back restores dephosphorylation. Reason: The activity is real and central to KinB signalling, but the substrate is a phosphoprotein (phospho-AlgB), so phosphoprotein phosphatase activity (GO:0004721) is the specific supported term. Proposed replacements: phosphoprotein phosphatase activity Supporting Evidence: PMID:23024348 Together, these data argue that KinB exhibits phosphatase activity and can directly dephosphorylate AlgB. |
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Download this section (compressed HTML)Q: What signal does the KinB periplasmic sensor domain perceive, and does it shift the balance between kinase and phosphatase output?
Experiment: Screen candidate ligands (e.g. by thermal shift or ITC) against the purified KinB periplasmic domain and measure their effect on AlgB phosphorylation and dephosphorylation rates in vitro.
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