Rm. Schaaper et Rl. Dunn, EFFECT OF ESCHERICHIA-COLI DNAE ANTIMUTATOR MUTANTS ON MUTAGENESIS BYTHE BASE ANALOG N-4-AMINOCYTIDINE, Mutation research. Fundamental and molecular mechanisms of mutagenesis, 402(1-2), 1998, pp. 23-28
Previous studies in our laboratory have identified a set of mutations
in the Escherichia coli dnaE gene that confer increased accuracy of DN
A replication (antimutators). The dnaE gene encodes the polymerase sub
unit of DNA polymerase III holoenzyme that replicates the E. coli chro
mosome. Here, we have investigated their effect on mutagenesis by the
base analog N-4-aminocytidine (4AC). For three different mutational ma
rkers, rifampicin resistance, nalidixic acid resistance and lad forwar
d mutagenesis, the dnaE911 allele reduced 4AC-induced mutagenesis by a
pproximately 2.5-fold, while the dnaE915 allele reduced it by 2.5-, 3.
5- and 6.5-fold, respectively. We also investigated the dependence of
4AC mutagenesis on mutations in the MutHLS mismatch repair system and
the UvrABC nucleotide excision repair system. The results show that mu
tagenesis by 4AC is unaffected by defects in either system. The combin
ed results point to the critical role of the DNA polymerase in prevent
ing mutations by base analogs. (C) 1998 Elsevier Science B.V. All righ
ts reserved.