title: Mlh1-Mlh3, a meiotic crossover and DNA mismatch repair factor, is a Msh2-Msh3-stimulated endonuclease.
abstract: Crossing over between homologous chromosomes is initiated in meiotic prophase in most sexually reproducing organisms by the appearance of programmed double strand breaks throughout the genome. In Saccharomyces cerevisiae the double-strand breaks are resected to form three prime single-strand tails that primarily invade complementary sequences in unbroken homologs. These invasion intermediates are converted into double Holliday junctions and then resolved into crossovers that facilitate homolog segregation during Meiosis I. Work in yeast suggests that Msh4-Msh5 stabilizes invasion intermediates and double Holliday junctions, which are resolved into crossovers in steps requiring Sgs1 helicase, Exo1, and a putative endonuclease activity encoded by the DNA mismatch repair factor Mlh1-Mlh3. We purified Mlh1-Mlh3 and showed that it is a metal-dependent and Msh2-Msh3-stimulated endonuclease that makes single-strand breaks in supercoiled DNA. These observations support a direct role for an Mlh1-Mlh3 endonuclease activity in resolving recombination intermediates and in DNA mismatch repair.
authors.affiliation: From the Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Rogacheva
authors.forename: Carol M
authors.initials: CM
authors.lastname: Manhart
authors.forename: Cheng
authors.initials: C
authors.lastname: Chen
authors.forename: Alba
authors.initials: A
authors.lastname: Guarne
authors.forename: Jennifer
authors.initials: J
authors.lastname: Surtees
authors.forename: Eric
authors.initials: E
authors.lastname: Alani
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D053904:DNA Breaks, Single-Stranded; D045566:DNA, Cruciform / Q000235:genetics / Q000378:metabolism*; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis / Q000502:physiology*; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D051718:MutS Homolog 2 Protein / Q000235:genetics / Q000378:metabolism*; D000074081:MutS Homolog 3 Protein; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D045566:DNA, Cruciform; D004271:DNA, Fungal; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; C088859:MLH1 protein, S cerevisiae; C492408:MLH3 protein, S cerevisiae; C081696:MSH3 protein, S cerevisiae; D000074081:MutS Homolog 3 Protein; D029701:Saccharomyces cerevisiae Proteins; D003850:Deoxyribonuclease I; C489751:MSH2 protein, S cerevisiae; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D051718:MutS Homolog 2 Protein
keywords: Crossing Over; DNA Enzymes; DNA Mismatch Repair; DNA Recombination; DNA Repair; Endonuclease; Meiosis; Mlh1-Mlh3