Regulation of porin gene expression over a wide range of extracellular pH in Escherichia coli K‐12: Influence of a tolA mutation

Analysis of porin gene expression as a function of extracellular pH (pHo) showed that ompF and lamB expression passed through a maximum, whereas ompC expression passed through a minimum at pH 8. This pH-dependent control operated at both transcriptional and post-transcriptional levels of ompF, but only at the transcriptional level on ompC. Similar studies carried out with tolA, tol B and excC mutant strains showed that the TolA, TolB and ExcC proteins are involved in the pH regulation of porin genes.