The influence of excision repair on the distribution of N-propyl-N'-nitro-N-nitrosoguanidine-induced mutation in Escherichia coli.
To determine the influence of excision repair on the distribution of N-propyl-N'-nitro-N-nitrosoguanidine (PNNG)-induced mutation, we have analysed the DNA sequence changes of mutation induced at the lacI gene of Escherichia coli in a UvrB- strain. The mutagenic specificity was similar to that found in the wild-type strain. Base substitutions predominate; G:C----A:T transitions accounted for almost 75% of the mutational events, while G:C----T:A transversions constituted approximately 20% of the mutations. In both strains the distribution of G:C----A:T transitions was nonrandom, but the site specificity of the G:C----A:T transitions appear dissimilar, with the hot and cold sites occurring at different positions. A single - 1 frameshift was recovered in each strain but deletion events were absent in the excision-repair-deficient strain. The complexity of the sequence-specificity of PNNG might reflect the differential repair of n-propyl and iso-propyl adducts.
Biology Department, York University, Toronto, Ontario, Canada.
G M
GM
van der Vliet
M
M
Zielenska
M W
MW
Anderson
B W
BW
Glickman
D000477:Alkylating Agents / Q000633:toxicity*; D001483:Base Sequence; D004260:DNA Repair; D004269:DNA, Bacterial / Q000187:drug effects*; D004926:Escherichia coli / Q000235:genetics*; D008769:Methylnitronitrosoguanidine / Q000633:toxicity / Q000031:analogs & derivatives; D008969:Molecular Sequence Data; D009153:Mutagens; D009154:Mutation
D000477:Alkylating Agents; D004269:DNA, Bacterial; D009153:Mutagens; D008769:Methylnitronitrosoguanidine; C013659:propyl-N'-nitro-N-nitrosoguanidine