Requirement of Rad5 for DNA Polymerase -Dependent Translesion Synthesis in Saccharomyces cerevisiae

摘要

In yeast, Rad6–Rad18-dependent lesion bypass involves translesion synthesis (TLS) byDNApolymerases hnor z or Rad5-dependent postreplication repair (PRR) in which error-free replication through theDNAlesionnoccurs by template switching. Rad5 functions in PRR via its two distinct activities—a ubiquitin ligase thatnpromotes Mms2–Ubc13-mediated K63-linked polyubiquitination of PCNA at its lysine 164 residue and anDNAhelicase that is specialized for replication fork regression. Both these activities are important for Rad5’snability to function in PRR. Here we provide evidence for the requirement of Rad5 in TLS mediated by Polz.nUsing duplex plasmids carrying different site-specific DNAlesions—an abasic site, a cis–syn TT dimer, a (6-4)nTT photoproduct, or a G-AAF adduct—we show that Rad5 is needed for Polz-dependent TLS. Rad5 action innthis role is likely to be structural, since neither the inactivation of its ubiquitin ligase activity nor theninactivation of its helicase activity impairs its role in TLS.