title: Analysis of in vivo correction of defined mismatches in the DNA mismatch repair mutants msh2, msh3 and msh6 of Saccharomyces cerevisiae.
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.
authors.affiliation: Institut für Molekulare Genetik, Georg-August-Universität Göttingen, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Lühr
authors.forename: J
authors.initials: J
authors.lastname: Scheller
authors.forename: P
authors.initials: P
authors.lastname: Meyer
authors.forename: W
authors.initials: W
authors.lastname: Kramer
mesh_terms: D004260:DNA Repair / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D051718:MutS Homolog 2 Protein; D000074081:MutS Homolog 3 Protein; D009692:Nucleic Acid Heteroduplexes; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C081696:MSH3 protein, S cerevisiae; C098790:MSH6 protein, S cerevisiae; D000074081:MutS Homolog 3 Protein; D009692:Nucleic Acid Heteroduplexes; D029701:Saccharomyces cerevisiae Proteins; C489751:MSH2 protein, S cerevisiae; D051718:MutS Homolog 2 Protein