Cloning of the regulatory locus ompB of Salmonella typhimurium LT-2. II. Identification of the envZ gene product, a protein involved in the expression of the porin proteins.

We have isolated the envZ gene from a recombinant plasmid carrying the complete ompB region of Salmonella typhimurium (Liljeström et al. 1982). The gene was found to be situated very near the ompR gene in the ompB locus. Using minicells, the envZ gene product was identified as a 46 kd protein. Strains harboring either an ompR+ plasmid or an envZ+ ompR+ plasmid were found to differ in their response to environmental changes with respect to porin protein expression. The results obtained suggest that the EnvZ protein, together with ompR, ultimately determines the level of expression of the porin proteins.