recA-dependent and recA-independent N-ethyl-N-nitrosourea mutagenesis at a plasmid-encoded herpes simplex virus thymidine kinase gene in Escherichia coli.

摘要: We have compared isogenic recA13/recA+ Escherichia coli K-12 strains for the induction by N-ethyl-N-nitrosourea (ENU) of forward mutations at a plasmid-encoded herpes simplex virus type 1 thymidine kinase (HSV-tk) gene. Treatment plasmid-bearing bacteria with ENU resulted in dose-dependent increase mutant frequencies chromosomal udk locus and plasmid HSV-tk both recA13 recA+ strains. Although strain was considerably more sensitive to cytotoxic effects treatment than strain, ENU-induced mutation frequency loci greater strain. When DNA modified vitro reaction used transform recA13, recA+, UV pre-irradiated strains, an observed all 3 cases. The followed similar dose-response, while significantly bacteria. These results indicate that fixation premutagenic lesions can occur recA-dependent recA-independent pathways.