Sensor histidine kinase EnvZ

UniProtKB accession:  P0AEJ4

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UniProtKB description:  Member of the two-component regulatory system EnvZ/OmpR involved in osmoregulation (particularly of genes ompF and ompC) as well as other genes (PubMed:2997120, PubMed:3536870). EnvZ functions as a membrane-associated protein kinase that phosphorylates OmpR in response to environmental signals; at low osmolarity OmpR activates ompF transcription, while at high osmolarity it represses ompF and activates ompC transcription (PubMed:1323560, PubMed:2277041, PubMed:2558046, PubMed:2656684, PubMed:2668281, PubMed:2668953, PubMed:2674113). Also dephosphorylates OmpR in the presence of ATP (PubMed:1323560, PubMed:2277041, PubMed:2558046, PubMed:2668281). The cytoplasmic dimerization domain (CDD) forms an osmosensitive core; increasing osmolarity stabilizes this segment (possibly by its contraction), enhancing the autophosphorylation rate and consequently, downstream phosphotransfer to OmpR and signaling (PubMed:22543870, PubMed:28256224). Autophosphorylation is greater when full-length EnvZ is reconstituted in a lipid environment, lipid-mediated allostery impacts the kinase function of EnvZ (PubMed:28256224). Involved in acid stress response; this requires EnvZ but not OmpR phosphorylation, and suggests that EnvZ senses cytoplasmic acidic pH (PubMed:29138484).