The Pol beta-14 dominant negative rat DNA polymerase beta mutator mutant commits errors during the gap-filling step of base excision repair in Saccharomyces cerevisiae

J Bacteriol. 1998 May;180(9):2292-7. doi: 10.1128/JB.180.9.2292-2297.1998.


We demonstrated recently that dominant negative mutants of rat DNA polymerase beta (Pol beta) interfere with repair of alkylation damage in Saccharomyces cerevisiae. To identify the alkylation repair pathway that is disrupted by the Pol beta dominant negative mutants, we studied the epistatic relationship of the dominant negative Pol beta mutants to genes known to be involved in repair of DNA alkylation damage in S. cerevisiae. We demonstrate that the rat Pol beta mutants interfere with the base excision repair pathway in S. cerevisiae. In addition, expression of one of the Pol beta dominant negative mutants, Pol beta-14, increases the spontaneous mutation rate of S. cerevisiae whereas expression of another Pol beta dominant negative mutant, Pol beta-TR, does not. Expression of the Pol beta-14 mutant in cells lacking APN1 activity does not result in an increase in the spontaneous mutation rate. These results suggest that gaps are required for mutagenesis to occur in the presence of Pol beta-14 but that it is not merely the presence of a gap that results in mutagenesis. Our results suggest that mutagenesis can occur during the gap-filling step of base excision repair in vivo.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkylation
  • Animals
  • DNA Damage
  • DNA Glycosylases*
  • DNA Polymerase beta / genetics*
  • DNA Polymerase beta / metabolism
  • DNA Repair Enzymes
  • DNA Repair*
  • Endodeoxyribonucleases / genetics
  • Endodeoxyribonucleases / metabolism
  • Epistasis, Genetic
  • Holliday Junction Resolvases
  • Mutagenesis*
  • Mutation
  • N-Glycosyl Hydrolases / genetics
  • N-Glycosyl Hydrolases / metabolism
  • Rats
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*


  • Saccharomyces cerevisiae Proteins
  • DNA Polymerase beta
  • Endodeoxyribonucleases
  • CCE1 protein, S cerevisiae
  • Holliday Junction Resolvases
  • Apn1 protein, S cerevisiae
  • 3-methyladenine-DNA glycosylase
  • DNA Glycosylases
  • N-Glycosyl Hydrolases
  • DNA Repair Enzymes