[Membrane proteins in Escherichia coli: effect of orthophosphate and mutation on regulatory genes of secreted alkaline phosphatase].

To elucidate the regulatory function of membranes during the biosynthesis of secreted alkaline phosphatase in E. coli, the protein compositions of membranes and periplasm in the E. coli wild strain and two mutants on regulatory phoS and phoRc genes of alkaline phosphatase have been studied during repressed and derepressed biosyntheses of enzymes. The biosynthesis of one of the membrane proteins is regulated by exogenous orthophosphate in parallel with alkaline phosphatase and a number of other periplasmic proteins (three of them have not been described in literature before). This regulation is determined by phoS gene common to alkaline phosphatase. The mutants of regulatory genes of alkaline phosphatase have a decreased content of membrane proteins or completely lack them. Mutations in the phoRc gene result in the loss of alkaline phosphatase and two membrane proteins and do not affect the biosynthesis of periplasmic proteins. Mutation in phoS gene diminishes the content of the other two membrane proteins, one of which is assumed to be the product of gene phoS--phosphate binding protein. The possible membrane localization of products of regulatory phoRc and phoS genes of alkaline phosphatase and participation of membrane proteins in the enzyme biosynthesis and its regulation are discussed.