CadC activates pH-dependent expression of the Vibrio vulnificus cadBA operon at a distance through direct binding to an upstream region.

The Vibrio vulnificus cadBA genes were transcribed as a transcriptional operon by a single promoter, P(cadBA), which was activated by CadC in a pH-dependent manner. A direct interaction between CadC and the P(cadBA) DNA was demonstrated, and a CadC binding site centered at -233.5 was mapped by deletion analyses of P(cadBA) and confirmed by a DNase I protection assay.