Involvement of the Escherichia coli Phosphoenolpyruvate‐Dependent Phosphotransferase System in Regulation of Transcription of Catabolic Genes

Abstract

Synthesis of catabolite-sensitive enzymes is repressed in mutants defective in the general proteins (enzyme I and HPr) of the E. coli phosphoenolpyruvate-dependent phosphotransferase system (ptsI and ptsH mutations). To elucidate the mechanism of this phenomenon, isogenic strains carrying pts mutations and different lesions of regulation of the lac operon or mutations affecting adenylate cyclase activity (cya mutation) and synthesis of cyclic-AMP-receptor protein (crp mutation) were constructed. Measurements of the differential rate of .beta.-galactosidase synthesis in these strains showed that the repressive effect of pts mutations was revealed in lac+, lacI, lacOc and cya bacteria, but it was lost in lacP and crp strains. Mutational damage to the general components of the phosphoenolpyruvate-dependent phosphotransferase system apparently diminishes activity of the lac promoter. The results showed that pts gene products (apparently phospho .apprx. HPr) are necessary for the initiation of transcription of catabolite-sensitive operons in E. coli.