Extensive 3'-overhanging, single-stranded DNA associated with the meiosis-specific double-strand breaks at the ARG4 recombination initiation site.
Meiosis-specific double-strand breaks occur at the initiation site for meiotic gene conversion in the yeast ARG4 gene. Here we show that the break fragments end in extensive 3'-overhanging, single-stranded tails. The single-stranded tails very in length, generating a gradient of single-strandedness that parallels the gradient of gene conversion frequencies in ARG4. In strains carrying a rad50S mutation, which blocks meiotic recombination, the extensive single-stranded tails do not form, suggesting that their generation is an obligatory step in meiotic recombination. Using the rad50S mutant, we have mapped the site of the ARG4 break to a small region within the genetically defined recombination initiation site. These results strongly support the double-strand break model of meiotic recombination.
Sun
H
H
Department of Molecular Biology, Massachusetts General Hospital, Boston 02114.
Treco
D
D
Szostak
J W
JW
D004271:DNA, Fungal / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000502:physiology*; D005785:Gene Conversion; D005800:Genes, Fungal / Q000235:genetics; D008540:Meiosis; D009154:Mutation; D011995:Recombination, Genetic / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004271:DNA, Fungal; D004277:DNA, Single-Stranded