title: Separation-of-function mutations in Saccharomyces cerevisiae MSH2 that confer mismatch repair defects but do not affect nonhomologous-tail removal during recombination.
abstract: Yeast Msh2p forms complexes with Msh3p and Msh6p to repair DNA mispairs that arise during DNA replication. In addition to their role in mismatch repair (MMR), the MSH2 and MSH3 gene products are required to remove 3' nonhomologous DNA tails during genetic recombination. The mismatch repair genes MSH6, MLH1, and PMS1, whose products interact with Msh2p, are not required in this process. We have identified mutations in MSH2 that do not disrupt genetic recombination but confer a strong defect in mismatch repair. Twenty-four msh2 mutations that conferred a dominant negative phenotype for mismatch repair were isolated. A subset of these mutations mapped to residues in Msh2p that were analogous to mutations identified in human nonpolyposis colorectal cancer msh2 kindreds. Approximately half of the these MMR-defective mutations retained wild-type or nearly wild-type activity for the removal of nonhomologous DNA tails during genetic recombination. The identification of mutations in MSH2 that disrupt mismatch repair without affecting recombination provides a first step in dissecting the Msh-effector protein complexes that are thought to play different roles during DNA repair and genetic recombination.
authors.affiliation: Department of Molecular Biology, Cornell University, Ithaca, New York 14853-2703, USA.
authors.forename: B
authors.initials: B
authors.lastname: Studamire
authors.forename: G
authors.initials: G
authors.lastname: Price
authors.forename: N
authors.initials: N
authors.lastname: Sugawara
authors.forename: J E
authors.initials: JE
authors.lastname: Haber
authors.forename: E
authors.initials: E
authors.lastname: Alani
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D005785:Gene Conversion; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D051718:MutS Homolog 2 Protein; D009154:Mutation; D011995:Recombination, Genetic / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C489751:MSH2 protein, S cerevisiae; D051718:MutS Homolog 2 Protein