An altered spectrum of herpes simplex virus mutations mediated by an antimutator DNA polymerase

The mutation spectrum attributable to an antimutator DNA polymerase in a eukaryotic cell was examined. Drug-resistant thymidine kinase (tk) mutants derived from both a wild-type (wt) strain, KOS and an antimutator DNA polymerase (pol) mutant, PAAr5, of herpes simplex virus (HSV), were isolated, and the mutated tk genes were characterized at the sequence level. While both transition and frameshift mutations were found in the mutated tk genes derived from the wt KOS Pol, all the PAAr5-mediated mutants analyzed were frameshift mutations. These results imply that the wt HSV Pol is less faithful than the antimutator enzyme, at least in part, because of its propensity to mediate transition mutations.