Saccharomyces cerevisiae MSH2-MSH3 and MSH2-MSH6 complexes display distinct requirements for DNA binding domain I in mismatch recognition

J Mol Biol. 2007 Feb 9;366(1):53-66. doi: 10.1016/j.jmb.2006.10.099. Epub 2006 Nov 3.


In eukaryotic mismatch repair (MMR) MSH2-MSH6 initiates the repair of base-base and small insertion/deletion mismatches while MSH2-MSH3 repairs larger insertion/deletion mismatches. Here, we show that the msh2Delta1 mutation, containing a complete deletion of the conserved mismatch recognition domain I of MSH2, conferred a separation of function phenotype with respect to MSH2-MSH3 and MSH2-MSH6 functions. Strains bearing the msh2Delta1 mutation were nearly wild-type in MSH2-MSH6-mediated MMR and in suppressing recombination between DNA sequences predicted to form mismatches recognized by MSH2-MSH6. However, these strains were completely defective in MSH2-MSH3-mediated MMR and recombination functions. This information encouraged us to analyze the contributions of domain I to the mismatch binding specificity of MSH2-MSH3 in genetic and biochemical assays. We found that domain I in MSH2 contributed a non-specific DNA binding activity while domain I of MSH3 appeared important for mismatch binding specificity and for suppressing non-specific DNA binding. These observations reveal distinct requirements for the MSH2 DNA binding domain I in the repair of DNA mismatches and suggest that the binding of MSH2-MSH3 to mismatch DNA involves protein-DNA contacts that appear very different from those required for MSH2-MSH6 mismatch binding.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Pair Mismatch*
  • Binding Sites
  • DNA Mismatch Repair*
  • DNA, Fungal / genetics*
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Lysine / genetics
  • Molecular Sequence Data
  • MutS Homolog 2 Protein / genetics*
  • MutS Homolog 2 Protein / metabolism
  • MutS Homolog 3 Protein
  • Protein Structure, Tertiary
  • Recombination, Genetic
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Structure-Activity Relationship
  • Substrate Specificity


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