Increased spontaneous mutation and alkylation sensitivity of Escherichia coli strains lacking the ogt O6-methylguanine DNA repair methyltransferase.

摘要: Abstract Escherichia coli expresses two DNA repair methyltransferases (MTases) that the mutagenic O6-methylguanine (O6MeG) and O4-methylthymine (O4MeT) lesions; one is product of inducible ada gene, here we confirm other constitutive ogt gene. We have generated various disruption mutants. Double mutants (ada ogt) do not express any O6MeG/O4MeT MTases, indicating Ada Ogt are probably only MTases in E. coli. were more sensitive to alkylation-induced mutation, arose linearly with dose, unlike ogt+ cells, which had a threshold dose below no accumulated; this ogt(+)-dependent was seen both ada+ strains. also killing (in an background), overexpression MTase from plasmid provided ada, but ada+, cells increased resistance by alkylating agents. The induction adaptive response normal infer these results prevents mutagenesis low levels agents that, protects found higher rate spontaneous mutation than wild-type, occurred nondividing cells. there endogenous source O6MeG or O4MeT damage prevalent