Mutator alleles of yeast DNA polymerase ζ

Ayako N. Sakamoto, Jana E. Stone, Grace E. Kissling, Scott D. McCulloch, Youri I. Pavlov, Thomas A. Kunkel

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The yeast REV3 gene encodes the catalytic subunit of DNA polymerase zeta (pol ζ), a B family polymerase that performs mutagenic DNA synthesis in cells. To probe pol ζ mutagenic functions, we generated six mutator alleles of REV3 with amino acid replacements for Leu979, a highly conserved residue inferred to be at the pol ζ active site. Replacing Leu979 with Gly, Val, Asn, Lys, Met or Phe resulted in yeast strains with elevated UV-induced mutant frequencies. While four of these strains had reduced survival following UV irradiation, the rev3-L979F and rev3-L979M strains had normal survival, suggesting retention of pol ζ catalytic activity. UV mutagenesis in the rev3-L979F background was increased when photoproduct bypass by pol η was eliminated by deletion of RAD30. The rev3-L979F mutation had little to no effect on mutagenesis in an ogg1Δ background, which cannot repair 8-oxo-guanine in DNA. UV-induced can1 mutants from rev3-L979F and rad30Δ rev3-L979F strains primarily contained base substitutions and complex mutations, suggesting error-prone bypass of UV photoproducts by L979F pol ζ. Spontaneous mutation rates in rev3-L979F and rev3-L979M strains are elevated by about two-fold overall and by two- to eight-fold for C to G transversions and complex mutations, both of which are known to be generated by wild-type pol ζ in vitro. These results indicate that Rev3p-Leu979 replacements reduce the fidelity of DNA synthesis by yeast pol ζ in vivo. In conjunction with earlier studies, the data establish that the conserved amino acid at the active site location occupied by Leu979 is critical for the fidelity of all four yeast B family polymerases. Reduced fidelity with retention of robust polymerase activity suggests that the homologous rev3-L979F allele may be useful for analyzing pol ζ functions in mammals, where REV3 deletion is lethal.

Original languageEnglish (US)
Pages (from-to)1829-1838
Number of pages10
JournalDNA Repair
Volume6
Issue number12
DOIs
StatePublished - Dec 1 2007

Keywords

  • Mutagenesis
  • Pol ζ
  • Translesion synthesis
  • Yeast

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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