title: Precise excision of Tn10 in Salmonella typhimurium: effects of mutations in the polA, dam, mutH and mutB genes and of methionine or ethionine in the plating medium.
abstract: Precise excision of Tn10 occurs at significantly elevated frequencies in cultures of the polA7 mutant strain of Salmonella typhimurium, is further increased in polA7 dam-1 and polA7 mutB strains and decreased in a polA7 mutH background. The numbers of precise excision events occurring in polA7 strains are also significantly increased when methionine (20 micrograms/ml or less) is present in the medium but decreased when ethionine (again, 20 micrograms/ml or less) is present. When both amino present, the outcome is about a 2-fold increase in precise excision events. The involvement of mismatch repair and methylation patterns in precise excision events is discussed.
authors.affiliation: Department of Microbiology, La Trobe University, Bundoora, Vic., Australia.
authors.forename: L M
authors.initials: LM
authors.lastname: Hafner
authors.forename: D G
authors.initials: DG
authors.lastname: MacPhee
mesh_terms: D004260:DNA Repair; D004251:DNA Transposable Elements / Q000187:drug effects; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D005001:Ethionine / Q000494:pharmacology*; D005798:Genes, Bacterial; D008715:Methionine / Q000494:pharmacology*; D008745:Methylation; D009154:Mutation; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D008715:Methionine; D005001:Ethionine