title: Mutagenic and comutagenic effects of ethionine in Escherichia coli K12.
abstract: A possible mutagenic and comutagenic activity of ethionine, an analog of the amino acid methionine, was investigated in several mutant strains of E. coli K12. Ethionine was found to act as a weak mutagen only in a mismatch repair deficient mutator strain (mutL) and as a comutagen with 2-aminopurine (2AP) in a wild type E. coli. The latter effect was nor observed in a restriction-deficient strain (r-) nor in a recombination or SOS-deficient recA strain. These effects are interpreted as a consequence of restriction-induced double-strand breaks in hypomethylated E. coli DNA resulting in induction of the SOS mutator effect which generates predominantly mismatch correctable untargeted mutations.
mesh_terms: D015075:2-Aminopurine / Q000494:pharmacology*; D000225:Adenine / Q000031:analogs & derivatives*; D001426:Bacterial Proteins / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005001:Ethionine / Q000494:pharmacology*; D008745:Methylation; D011938:Rec A Recombinases / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015075:2-Aminopurine; D004248:DNA (Cytosine-5-)-Methyltransferases; D011938:Rec A Recombinases; D000225:Adenine; D005001:Ethionine