THE SACCHAROMYCES-CEREVISIAE RAD30 GENE, A HOMOLOG OF ESCHERICHIA-COLI DINB AND UMUC, IS DNA-DAMAGE INDUCIBLE AND FUNCTIONS IN A NOVEL ERROR-FREE POSTREPLICATION REPAIR MECHANISM

Damage-inducible mutagenesis in prokaryotes is largely dependent upon the activity of the UmuD'C-like proteins. Since many DNA repair proces ses are structurally and/or functionally conserved between prokaryotes and eukaryotes, we investigated the role of RAD30, a previously uncha racterized Saccharomyces cerevisiae DNA repair gene related to the Esc herichia coli dinB, umuC and S. cerevisiae REV1 genes, in UV resistanc e and UV-induced mutagenesis. Similar to its prokaryotic homologues, R AD30 was found to be damage inducible. Like many S. cerevisiae genes i nvolved in error-prone DNA repair, epistasis analysis clearly places R AD30 in the XAD6 group and rad30 mutants display moderate UV sensitivi ty reminiscent of rev mutants. However, unlike rev mutants, no defect in UV-induced reversion was seen in rad30 strains. While rad6 and rad1 8 are both epistatic to rad30, no epistasis was observed with rev1, re v3, rev7 or rad5, all of which are members of the RAD6 epistasis group . These findings suggest that RAD30 participates in a novel error-free repair pathway dependent on RAD6 and RAD18, but independent of REV1, REV3 REV7 and RAD5.