Cyclic AMP receptor protein functions as a repressor of the osmotically inducible promoter proP P1 in Escherichia coli

The role of the cyclic adenosine monophosphate (cAMP) receptor protein (CRP) binding site at the proP P1 promoter region in the regulation of the P1 promoter was analyzed via site-directed mutagenesis. The site-directed mutagenesis of the CRP binding site indicated the role of the catabolite regulatory protein in inhibiting transcription at P1 under conditions of low to normal osmolality. Furthermore, the osmotic induction of the P1 promoter was dependent on the release of CRP-cAMP from its binding site within the promoter.