Spontaneous mutation in Escherichia coli containing the dnaE911 DNA polymerase antimutator allele

DNA sequencing and colony hybridization studies of the function of the dnaE911 DNA polymerase antimutator allele in spontaneous mutagenesis of Escherichia coli reveal that dnaE911 reduces galK, lacI and Rif mutations by 1.5 to 2-fold in the mismatch-repair proficient background. DNA sequences of the lacI gene mutants show that transitions, deletions, frameshifts and duplications remain stable, while a 3-fold reduction of transversions occurs in the dnaE911 allele presence. The A.T to T.A transversion undergoes a 6-fold reduction while the A.T to G.C base-pair substitution hotspot in the lac operator undergoes 5-fold decrease, suggesting that dnaE911 allelic activity is genetic background and mutation type specific.