Role of Major Outer Membrane Proteins of Escherichia coli in the Antimicrobial Action of Polyphosphate

Abstract

E. coli JE 1011 and its NS mutants were classified into polyphosphate (PP)-resistant strains (JE 1011, NS 3, NS 5), PP-sensitive strains (NS 2, NS 4, NS 6), and a PP-sensitivity changeablestrain (NS 1)depending on growth media. The PP-sensitive strains showed decreased amounts of matrix proteins (OmpF, OmpC) in the outer membrane. The release of OmpF from the cells was observed in the PP-sensitive strain with increased PP-sensitivity. When the outer membrane containing nonheated forms of matrix proteins (OmpF^*, OmpC^*)were treated with PP, themobility of these proteins on SDS gel electrophoresis changed, especially OmpF^*. Pretreatment of PP with PP-sensitive strains and osmotically shocked cells inhibited the oxidation of sugars, organic acids and medium components. This effect was not observed with PP-resistant strainsand NS 1. In these compounds the oxidation inhibition by PP appeared to be at the permeability level of the outer membrane.
These results suggested that PP could affect to matrix protein which involved in the permeation of various hydrophilic, small molecules through the outer membrane. We supposed, therefore, that the growth inhibitory effect of PP in PP-sensitive strains might be caused by the lack of nutrition essential to bacteria growth.