title: Proofreading-defective DNA polymerase II increases adaptive mutation in Escherichia coli.
abstract: The role of Escherichia coli DNA polymerase (Pol) II in producing or avoiding mutations was investigated by replacing the chromosomal Pol II gene (polB+) by a gene encoding an exonuclease-deficient mutant Pol II (polBex1). The polBex1 allele increased adaptive mutations on an episome in nondividing cells under lactose selection. The presence of a Pol III antimutator allele (dnaE915) reduced adaptive mutations in both polB+ cells and cells deleted for polB (polB delta 1) to below the wild-type level, suggesting that both Pol II and Pol III are synthesizing episomal DNA in nondividing cells but that in wild-type cells Pol III generates the adaptive mutations. The adaptive mutations were mainly -1 frame-shifts occurring in short homopolymeric runs and were similar in wild-type, polB delta 1, and polBex1 strains. Mutations produced by both Pol III and Pol II ex1 were corrected by the mutHLS mismatch repair system.
authors.affiliation: Department of Environmental Health, Boston University School of Public Health, MA 02118-2394, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Foster
authors.forename: G
authors.initials: G
authors.lastname: Gudmundsson
authors.forename: J M
authors.initials: JM
authors.lastname: Trimarchi
authors.forename: H
authors.initials: H
authors.lastname: Cai
authors.forename: M F
authors.initials: MF
authors.lastname: Goodman
mesh_terms: D000064:Acclimatization; D000483:Alleles; D001483:Base Sequence; D002876:Chromosomes, Bacterial; D004257:DNA Polymerase II / Q000378:metabolism*; D004258:DNA Polymerase III / Q000378:metabolism; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000235:genetics; D005798:Genes, Bacterial; D005838:Genotype; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D016133:Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D004257:DNA Polymerase II; D004258:DNA Polymerase III; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V