Mutator effects of overproducing DNA polymerase eta (Rad30) and its catalytically inactive variant in yeast

Mutat Res. 2001 Jul 1;478(1-2):129-39. doi: 10.1016/s0027-5107(01)00131-2.


DNA polymerase eta synthesizes DNA in vitro with low fidelity. Based on this, here we report the effects of deletion or increased expression of yeast RAD30 gene, encoding for polymerase eta (Pol eta), on spontaneous mutagenesis in vivo. Deletion of RAD30 did not affect spontaneous mutagenesis. Overproduction of Rad30p was slightly mutagenic in a wild-type yeast strain and moderately mutagenic in strains with inactive 3'-->5'-exonuclease of DNA polymerase epsilon or DNA mismatch repair. These data suggest that excess Rad30p reduces replication fidelity in vivo and that the induced errors may be corrected by exonucleolytic proofreading and DNA mismatch repair. However, the magnitude of mutator effect (only up to 10-fold) suggests that the replication fork is protected from inaccurate synthesis by Pol eta in the absence of DNA damage. Overproduction of catalytically inactive Rad30p was also mutagenic, suggesting that much of the mutator effect results from indirect perturbation of replication rather than from direct misincorporation by Pol eta. Moreover, while excess wild-type Pol eta primarily induced base substitutions in the msh6 and pms1 strains, excess inactive Rad30p induced both base substitutions and frameshifts. This suggests that more than one mutagenic mechanism is operating when RAD30 is overexpressed.

MeSH terms

  • Base Sequence
  • Catalysis
  • Cell Division / drug effects
  • Cell Division / genetics
  • Cell Division / radiation effects
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Dose-Response Relationship, Radiation
  • Galactose / pharmacology
  • Gene Deletion
  • Gene Frequency
  • Genetic Variation
  • Genotype
  • Glucose / pharmacology
  • Mutagenesis
  • Mutation
  • Point Mutation
  • Recombinant Fusion Proteins / drug effects
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Ultraviolet Rays


  • Recombinant Fusion Proteins
  • DNA-Directed DNA Polymerase
  • Rad30 protein
  • Glucose
  • Galactose