The Relative Roles in Vivo of Saccharomyces cerevisiae Pol η, Pol ζ, Rev1 Protein and Pol32 in the Bypass and Mutation Induction of an Abasic Site, T-T (6-4) Photoadduct and T-T cis-syn Cyclobutane Dimer

Publisher Website
Google Scholar
Abstract
We have investigated the relative roles in vivo of Saccharomyces cerevisiae DNA polymerase η, DNA polymerase ζ, Rev1 protein, and the DNA polymerase δ subunit, Pol32, in the bypass of an abasic site, T-T (6-4) photoadduct and T-T cis-syn cyclobutane dimer, by transforming strains deleted for RAD30, REV3, REV1, or POL32 with duplex plasmids carrying one of these DNA lesions located within a 28-nucleotide single-stranded region. DNA polymerase η was found to be involved only rarely in the bypass of the T-T (6-4) photoadduct or the abasic sites in the sequence context used, although, as expected, it was solely responsible for the bypass of the T-T dimer. We argue that DNA polymerase ζ, rather than DNA polymerase δ as previously suggested, is responsible for insertion in bypass events other than those in which polymerase η performs this function. However, DNA polymerase δ is involved indirectly in mutagenesis, since the strain lacking its Pol32 subunit, known to be deficient in mutagenesis, shows as little bypass of the T-T (6-4) photoadduct or the abasic sites as those deficient in Pol ζ or Rev1. In contrast, bypass of the T-T dimer in the pol32Δ strain occurs at the wild-type frequency.