Analysis of in vivo correction of defined mismatches in the DNA mismatch repair mutants msh2, msh3 and msh6 of Saccharomyces cerevisiae

Mol Gen Genet. 1998 Feb;257(3):362-7. doi: 10.1007/s004380050658.

Abstract

We have analysed the correction of defined mismatches in wild-type and msh2, msh3, msh6 and msh3 msh6 mutants of Saccharomyces cerevisiae in two different yeast strain backgrounds by transformation with plasmid heteroduplex DNA constructs. Ten different base/base mismatches, two single-nucleotide loops and a 38-nucleotide loop were tested. Repair of all types of mismatches was severely impaired in msh2 and msh3 msh6 mutants. In msh6 mutants, repair efficiency of most base/base mismatches was reduced to a similar extent as in msh3 msh6 double mutants. G/T and A/C mismatches, however, displayed residual repair in msh6 mutants in one strain background, implying a role for Msh3p in recognition of base/base mismatches. Furthermore, the efficiency of repair of base/base mismatches was considerably reduced in msh3 mutants in one strain background, indicating a requirement for MSH3 for fully efficient mismatch correction. Also the efficiency of repair of the 38-nucleotide loop was reduced in msh3 mutants, and to a lesser extent in msh6 mutants. The single-nucleotide loop with an unpaired A was less efficiently repaired in msh3 mutants and that with an unpaired T was less efficiently corrected in msh6 mutants, indicating non-redundant functions for the two proteins in the recognition of single-nucleotide loops.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Repair / genetics*
  • DNA, Fungal / genetics*
  • DNA-Binding Proteins / genetics
  • Fungal Proteins / genetics
  • Genes, Fungal / genetics*
  • MutS Homolog 2 Protein
  • MutS Homolog 3 Protein
  • Nucleic Acid Heteroduplexes
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*

Substances

  • DNA, Fungal
  • DNA-Binding Proteins
  • Fungal Proteins
  • MSH3 protein, S cerevisiae
  • MSH6 protein, S cerevisiae
  • MutS Homolog 3 Protein
  • Nucleic Acid Heteroduplexes
  • Saccharomyces cerevisiae Proteins
  • MSH2 protein, S cerevisiae
  • MutS Homolog 2 Protein