title: Overproduction of the epsilon subunit of DNA polymerase III counteracts the SOS mutagenic response of Escherichia coli.
abstract: It has been found that the mutator phenotype of the recA441 and recA730 strains that express the SOS response constitutively is suppressed by pIP1, a high-copy plasmid carrying the dnaQ gene encoding the 3'----5' exonuclease subunit (epsilon) of DNA polymerase III. We have constructed plasmid pIP11, in which the dnaQ gene is fused to the strong tac (trp-lac) promoter. Enhanced synthesis of the epsilon subunit stimulated by isopropyl beta-D-thiogalactopyranoside, the inducer of tac, prevents expression of the mutator phenotype of recA441 and markedly decreases the frequency of UV-induced mutations. These results strongly suggest that a loss of editing capacity by the epsilon subunit of DNA polymerase III holoenzyme plays a crucial role in generation of mutations during the SOS response.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw.
authors.forename: P
authors.initials: P
authors.lastname: Jonczyk
authors.forename: I
authors.initials: I
authors.lastname: Fijalkowska
authors.forename: Z
authors.initials: Z
authors.lastname: Ciesla
mesh_terms: D004258:DNA Polymerase III / Q000096:biosynthesis / Q000235:genetics*; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000528:radiation effects; D005838:Genotype; D046911:Macromolecular Substances; D009154:Mutation; D010957:Plasmids; D013014:SOS Response, Genetics; D014466:Ultraviolet Rays
chemical_list: D046911:Macromolecular Substances; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase