Mutations that alter the DNA sequence specificity of the catabolite gene activator protein of E. coli

Three mutations that alter the DNA sequence specificity of the catabolite gene activator protein (CAP) from AA-TGTGA--T---TCA-ATW to AA-TGTAA--T---TCA-ATW have been isolated. All three mutations affect the same amino acid of CAP, glutamic acid 181. We propose that it is this amino acid of CAP that makes contacts with base pairs 7 and 16 of the symmetrical recognition site.