Regulation of the lkyB gene expression in Escherichia coli K-12 strains carrying an lkyB-lacZ gene fusion.

Phage MudII301 was used to isolate new periplasmic-leaky mutants of Escherichia coli K12 carrying an lkyB-lacZ gene fusion. The properties of strain JC2299 carrying the lkyB-2299 insertion mutation were identical to those of strain JC207 carrying the previously described lkyB-207 mutation. The LkyB-beta-galactosidase hybrid protein was partially extracellular and membrane bound. It was shown that both a nonsense (envZ-22) and a polar (ompR::Tn10) mutation in the ompB operon led to an increase of beta-galactosidase activity in the lkyB-lacZ fusion strain. On the other hand, mutations in the phoB, phoR, phoS, phoT, malT or envY genes had no effect on lkyB gene expression.