title: Trans events associated with crossovers are revealed in the absence of mismatch repair genes in Saccharomyces cerevisiae.
abstract: Genetic analysis of recombination in Saccharomyces cerevisiae has revealed products with structures not predicted by the double-strand break repair model of meiotic recombination. A particular type of recombinant containing trans heteroduplex DNA has been observed at two loci. Trans events were originally identified only in tetrads in which the non-Mendelian segregations were not associated with a crossover. Because of this, these events were proposed to have arisen from the unwinding of double Holliday junctions. Previous studies used palindromes, refractory to mismatch repair, as genetic markers whereas we have used a complementary approach of deleting mismatch repair proteins to identify heteroduplex DNA. We found that the markers occurred in trans and were associated with crossovers. In both mlh1Delta and msh2Delta strains, the frequency of trans events associated with a crossover exceeded that predicted from the random association of crossovers with noncrossover trans events. We propose two different models to account for trans events associated with crossovers and discuss the relevance to wild-type DSB repair.
authors.affiliation: Department of Genetics, University of Leicester, UK.
authors.forename: Eva R
authors.initials: ER
authors.lastname: Hoffmann
authors.forename: Rhona H
authors.initials: RH
authors.lastname: Borts
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics; D000619:Aminohydrolases / Q000235:genetics; D020137:Base Pair Mismatch; D003434:Crossing Over, Genetic / Q000235:genetics*; D004260:DNA Repair; D005800:Genes, Fungal; D008957:Models, Genetic; D011755:Pyrophosphatases / Q000235:genetics; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000429:Alcohol Oxidoreductases; C092116:HIS4 protein, S cerevisiae; D000619:Aminohydrolases; D011755:Pyrophosphatases