Quantifying the contributions of base selectivity, proofreading and mismatch repair to nuclear DNA replication in Saccharomyces cerevisiae

• Published in: DNA repair Vol. 31; pp. 41 - 51
• Main Authors: St Charles, Jordan A., Liberti, Sascha E., Williams, Jessica S., Lujan, Scott A., Kunkel, Thomas A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-07-2015
• Subjects: Base Pair Mismatch; Base Sequence; DNA Mismatch Repair; DNA polymerase; DNA Polymerase III - genetics; DNA Polymerase III - metabolism; DNA Replication; Genome stability; Molecular Sequence Data; Mutation rate; Replication fidelity; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Mutation rate; Replication fidelity; DNA polymerase; Genome stability
• ISSN: 1568-7864; 1568-7856
• DOI: 10.1016/j.dnarep.2015.04.006

•The base selectivity of the major replicases in vivo is higher than measured in vitro.•A variable balance between proofreading and MMR underlies replication fidelity•Proofreading contributes more to replication fidelity than does MMR.•Differences in proofreading and MMR may be relevant to tissue-specific tumorigenesis.
Mismatches generated during eukaryotic nuclear DNA replication are removed by two evolutionarily conserved error correction mechanisms acting in series, proofreading and mismatch repair (MMR). Defects in both processes are associated with increased susceptibility to cancer. To better understand these processes, we have quantified base selectivity, proofreading and MMR during nuclear DNA replication in Saccharomyces cerevisiae. In the absence of proofreading and MMR, the primary leading and lagging strand replicases, polymerase ɛ and polymerase δ respectively, synthesize DNA in vivo with somewhat different error rates and specificity, and with apparent base selectivity that is more than 100 times higher than measured in vitro. Moreover, leading and lagging strand replication fidelity rely on a different balance between proofreading and MMR. On average, proofreading contributes more to replication fidelity than does MMR, but their relative contributions vary from nearly all proofreading of some mismatches to mostly MMR of other mismatches. Thus accurate replication of the two DNA strands results from a non-uniform and variable balance between error prevention, proofreading and MMR.