title: The level of GC-->AT transitions induced by MMS is not affected by the adaptive response in Escherichia coli K12.
abstract: I have examined the effect of the adaptive response on the frequency of MMS-induced umuC-dependent AT-->TA transversions and umuC-independent, GC-->AT transitions. It was found that the induction of the adaptive response causes a moderate decrease (50-60%) in the frequency of AT-->TA transversions and surprisingly has no effect on the level of GC-->AT transitions. In contrast, a dramatic decrease in MNNG-induced mutations has been observed in adapted cultures. However, this effect was completely abolished by MMS pretreatment of adapted cells before MNNG challenge. A mechanism for the MMS interference with the repair of MNNG-induced mutations in adapted cells is proposed.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw.
authors.forename: E
authors.initials: E
authors.lastname: Sledziewska-Gójska
mesh_terms: D004260:DNA Repair / Q000187:drug effects*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D008741:Methyl Methanesulfonate / Q000494:pharmacology / Q000633:toxicity*; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology / Q000633:toxicity*; D008780:Methyltransferases / Q000378:metabolism; D016296:Mutagenesis; D009153:Mutagens; D009154:Mutation; D019853:O(6)-Methylguanine-DNA Methyltransferase; D013489:Suppression, Genetic
chemical_list: D009153:Mutagens; D008769:Methylnitronitrosoguanidine; D008741:Methyl Methanesulfonate; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase; D003850:Deoxyribonuclease I