Member of the two-component regulatory system EnvZ/OmpR involved in the regulation of osmoregulation (genes ompF and ompC). EnvZ functions as a membrane-associated protein kinase that phosphorylates OmpR in response to environmental signals (By similarity). This two-component system plays a role in virulence (By similarity). ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Homodimer. Has several major domains; the N-terminal cytoplasmic domain is followed by 2 transmembrane helices that anchor the protein in the membrane; the periplasmic domain between the helices interacts with MrzA. The cytoplasmic C-terminal domain has a HAMP domain joined by a flexible linker to a histidine kinase domain. The HAMP domain by itself is intrinsically disordered. The cytoplasmic dimerization domain (CDD) forms an osmosensitive core and includes the autophosphorylated histidine residue. Autophosphorylated.