Nucleotide sequence changes produced by mutations in the lac promoter of Escherichia coli.

Nucleotide changes occurring in class I mutants of the /ao promoter have been determined. Mutants L8, L37, L65 and L592 produce a G. C to T-A transition at nucleotide 19, while L29, L146 and L614 produce a C 'G to A.T transition at nucleotide 28. These two mutational sites are symmetrically located in a sequence in which 12 of 14 nucleotides are related by a dyad axis. This region may be the binding site for the catabolite gone activator protein. In a previous publication (Dickson etal., 1975) we presented the nucleotide changes seen in the class I I promoter mutants, L241 and L305, and the class TII promoter mutant, prla. Here we present the data which determined these nucleotide changes.