title: mut-25, a mutation to mutator linked to purA in Escherichia coli.
abstract: The mutation mut-25 that results in a mutator phenotype is closely linked to purA on the chromosome of Escherichia coli. The gene order in this region is ampA mut-25 purA. purA mut-25 double mutants retained mutator activity indicating that mut-25 is not a mutation in the purA gene. The repair mutations uvrA6, recA56, and exrA1 had no effect on mutation frequencies in mut-25 strains, and mut-25 strains were normally resistant to ultraviolet irradiation. Frequencies of host range mutations were not increased in phages T1, T2, and T7 grown on mut-25 strains. mut-25 could act trans, reverting the trpA46 mutation either on the chromosome or on an F episome. The transitions AT yields GC (adenine-thymine yields guanine-cytosine) and GC yields AT were induced by mut-25.
mesh_terms: D001483:Base Sequence; D003090:Coliphages; D004260:DNA Repair; D004267:DNA Viruses; D004926:Escherichia coli / Q000378:metabolism* / Q000528:radiation effects; D005111:Extrachromosomal Inheritance; D005796:Genes; D008242:Lysogeny; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D010641:Phenotype; D011687:Purines / Q000096:biosynthesis*; D011830:Radiation Effects; D011995:Recombination, Genetic; D014161:Transduction, Genetic; D014364:Tryptophan / Q000096:biosynthesis; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D009604:Nitrosoguanidines; D011687:Purines; D014364:Tryptophan