SPECTRUM OF PROTON-INDUCED MUTAGENESIS OF THE ESCHERICHIA-COLI CRP GENE

Mutation of the adenosine 3',5'-cyclic monophosphate receptor protein gene (crp) of Escherichia coli induced by protons, ionizing radiation of charged particles, was analyzed to determine the specificity of the mutational spectrum. The majority, 44 of 49 mutations detected, were base substitutions, and three frameshifts and two gross structural cha nges were also found. Base substitutions included 35 transversions and nine transitions. G:C to T:A transversions were the dominant type of base substitution, followed by G:C to C:G and A:T to T:A transversions . Almost all transitions were eight G:C to A:T changes. The spectrum o f proton mutagenesis was quite different from that of X-ray mutagenesi s of the crp gene, in which G:C to A:T transitions dominated.