Fig. 1.
Schematic view of EnvZ/OmpR regulation. The HK EnvZ exists with N- and C-termini in the cytoplasm, contains two TMs in the inner membrane and a periplasmic loop in between TM1 and TM2. In response to intracellular osmolytes, autophosphorylation increases 10-fold at the conserved histidine residue (H243). The phosphoryl group is transferred to an aspartic acid residue on OmpR (D55) and OmpR ~ P binds to the regulatory regions of ompF and ompC porin genes to activate and/or repress transcription (“Non-pathogenesis”). In Salmonella, OmpR ~ P activates the SsrA/B TCRS that is located on pathogenicity island 2 (SPI-2) and is essential for virulence (“Pathogenesis”).