Molecular and General Genetics MGG

, Volume 242, Issue 3, pp 289–296

The 3′ → 5′ exonucleases of both DNA polymerases δ and ε participate in correcting errors of DNA replication in Saccharomyces cerevisiae

  • Alan Morrison
  • Akio Sugino
Originals Articles

DOI: 10.1007/BF00280418

Cite this article as:
Morrison, A. & Sugino, A. Molec. Gen. Genet. (1994) 242: 289. doi:10.1007/BF00280418


DNA polymerases II (ε) and III(δ) are the only nuclear DNA polymerases known to possess an intrinsic 3′ → 5′ exonuclease in Saccharomyces cerevisiae. We have investigated the spontaneous mutator phenotypes of DNA polymerase δ and ε 3′ → 5′ exonuclease-deficient mutants, pol3-01 and pol2-4, respectively. pol3-01 and pol2-4 increased spontaneous mutation rates by factors of the order of 102 and 101, respectively, measured as URA3 forward mutation and his7-2 reversion. Surprisingly, a double mutant pol2-4 pol3-01 haploid was inviable. This was probably due to accumulation of unedited errors, since a pol2-4/pol2-4 pol3-01/pol3-01 diploid was viable, with the spontaneous his7-2 reversion rate increased by about 2 × 103-fold. Analysis of mutation rates of double mutants indicated that the 3′ → 5′ exonucleases of DNA polymerases δ and ε can act competitively and that, like the 3′ → 5′ exonuclease of DNA polymerase δ the 3′ → 5′ exonuclease of DNA polymerase ε acts in series with the PMS1 mismatch correction system. Mutational spectra at a URA3 gene placed in both orientations near to a defined replication origin provided evidence that the 3′ → 5′ exonucleases of DNA polymerases δ and ε act on opposite DNA strands, but were in sufficient to distinguish conclusively between different models of DNA replication.

Key words

DNA polymerases ε and δ3′ → 5′ ExonucleaseReplication errorsSpontaneous mutationsSaccharomyces cerevisiae

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Alan Morrison
    • 1
  • Akio Sugino
    • 2
  1. 1.Laboratory of Molecular GeneticsNational Institute of Environmental Health SciencesResearch Triangle ParkUSA
  2. 2.Department of Molecular Immunology, Research Institute for Microbial DiseasesOsaka UniversitySuita, OsakaJapan