Localization of phoE, the structural gene for outer membrane protein e in Escherichia coli K-12.

To localize the structural gene for outer membrane protein e, mutants resistant to the protein e-specific phage TC45 were isolated and characterized. Three classes of TC45-resistant strains were found: (i) mutants in phoB, a regulatory gene for protein e, (ii) mutants with an altered lipopolysaccharide, and (iii) mutants unaltered in the regulation of the pho regulon and producing an apparently normal lipopolysaccharide. Mutations in the latter class of mutants are probably altered in the structural gene for protein e and are cotransducible with proA,B at min 6 on the chromosomal map. As class (iii) includes mutants with an electrophoretically altered protein e, in both an nmpA and an nmpB background, we conclude that the structural gene for protein e, designated as phoE, is localized at min 6 on the chromosomal map, the gene order being phoE proA argF.