Location of phosphorylation site and DNA-binding site of a positive regulator, OmpR, involved in activation of the osmoregulatory genes of Escherichia coli.

The OmpR protein of Escherichia coli is a positive regulator involved in activation of the ompF and ompC genes which encode the major outer membrane proteins OmpF and OmpC, respectively. By employing recombinant DNA techniques, we isolated the N- and C-terminal halves of the OmpR molecule. From the results of biochemical analyses of these fragments, it was concluded that the N-terminal portion contains a site involved in phosphorylation by an OmpR-specific protein kinase EnvZ, whereas the C-terminal part possesses a DNA-binding site for the ompC and ompF promoters.