The importance of genetic recombination for fidelity of chromosome pairing in meiosis.
In budding yeast, absence of the Hop2 protein leads to extensive synaptonemal complex (SC) formation between nonhomologous chromosomes, suggesting a crucial role for Hop2 in the proper alignment of homologous chromosomes during meiotic prophase. Genetic analysis indicates that Hop2 acts in the same pathway as the Rad51 and Dmc1 proteins, two homologs of E. coli RecA. Thus, the hop2 mutant phenotype demonstrates the importance of the recombination machinery in promoting accurate chromosome pairing. We propose that the Dmc1/Rad51 recombinases require Hop2 to distinguish homologous from nonhomologous sequences during the homology search process. Thus, when Hop2 is absent, interactions between nonhomologous sequences become inappropriately stabilized and can initiate SC formation. Overexpression of RAD51 largely suppresses the meiotic defects of the dmc1 and hop2 mutants. We conclude that Rad51 is capable of carrying out a homology search independently, whereas Dmc1 requires additional factors such as Hop2.
Tsubouchi
Hideo
H
Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Roeder
G Shirleen
GS
D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D023902:Chromosome Pairing / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D008540:Meiosis / Q000502:physiology*; D009154:Mutation / Q000502:physiology; D051135:Rad51 Recombinase; D011995:Recombination, Genetic / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D004718:Saccharomycetales / Q000235:genetics*; D013172:Spores, Fungal / Q000235:genetics
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; C513033:DMC1 protein, S cerevisiae; D004268:DNA-Binding Proteins; C113830:HOP2 protein, S cerevisiae; C454441:MND1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051135:Rad51 Recombinase