title: A direct role for DNA polymerase III in adaptive reversion of a frameshift mutation in Escherichia coli.
abstract: The sequences of adaptive reversions of a lac frameshift mutation in Escherichia coli resemble DNA polymerase errors, and the adaptive reversions decrease in strains with an antimutator DNA polymerase III (PolIII) allele. The latter finding could imply that DNA PolIII itself makes adaptive mutations. Alternatively, normal DNA PolIII errors could saturate post-synthesis mismatch repair during adaptive mutation. If so, the antimutator strain would produce fewer adaptive mutations because it possesses greater capacity for mismatch repair which could correct errors made by a polymerase other than DNA PolIII. Mismatch repair capacity is limited specifically during adaptive mutation, necessitating a test of this indirect model. This indirect model is ruled out here by the observation that the antimutator PolIII allele decreases adaptive mutation even in mismatch repair-defective cells. This supports a direct role for DNA PolIII in recombination-dependent adaptive mutation.
authors.affiliation: Department of Biochemistry, University of Alberta Faculty of Medicine, Edmonton, Canada. reuben_harris@darwin.biochem.ualberta.ca
authors.forename: R S
authors.initials: RS
authors.lastname: Harris
authors.forename: H J
authors.initials: HJ
authors.lastname: Bull
authors.forename: S M
authors.initials: SM
authors.lastname: Rosenberg
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000235:genetics; D004258:DNA Polymerase III / Q000235:genetics*; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D016368:Frameshift Mutation; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; D011938:Rec A Recombinases / Q000235:genetics; D011995:Recombination, Genetic; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D011938:Rec A Recombinases; D004258:DNA Polymerase III; D001616:beta-Galactosidase; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli