Interhomolog bias during meiotic recombination: meiotic functions promote a highly differentiated interhomolog-only pathway.
Meiotic recombination occurs preferentially between homologous nonsister chromatids rather than between sisters, opposite to the bias of mitotic recombinational repair. We have examined formation of joint molecule recombination intermediates (JMs) between homologs and between sisters in yeast strains lacking the meiotic chromosomal protein Red1, the meiotic recA homolog Dmc1, and/or mitotic recA homolog(s), Rad51, Rad55, and Rad57. Mutant phenotypes imply that most meiotic recombination occurs via an interhomolog-only pathway along which interhomolog bias is established early, prior to or during double strand break (DSB) formation, and then enforced, just at the time when DSBs initiate JM formation. A parallel, less differentiated pathway yields intersister and, probably, a few interhomolog events. Coordinate action of mitotic recA homologs as one functional unit, two functions of RED1, and an interhomolog interaction function of DMC1 are also revealed.
Schwacha
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Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Kleckner
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N
D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics; D045643:DNA Repair Enzymes; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000235:genetics; D008540:Meiosis / Q000502:physiology*; D008938:Mitosis / Q000235:genetics; D009154:Mutation / Q000502:physiology; D010641:Phenotype; D051135:Rad51 Recombinase; D011938:Rec A Recombinases / Q000235:genetics; D011995:Recombination, Genetic / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
D018797:Cell Cycle Proteins; C513033:DMC1 protein, S cerevisiae; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C087191:RAD55 protein, S cerevisiae; C086673:RED1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; D000251:Adenosine Triphosphatases; C071451:RAD57 protein, S cerevisiae; D045643:DNA Repair Enzymes