Research Article

A global view of meiotic double-strand break end resection

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Science  06 Jan 2017:
Vol. 355, Issue 6320, pp. 40-45
DOI: 10.1126/science.aak9704

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Recombination revealed by mapping tails

Meiosis is a specialized double cell division that generates haploid gametes from diploid parent cells. Meiotic recombination between homologous chromosomes ensures the proper segregation of chromosomes to the daughter cells. Mimitou et al. carried out a genome-wide survey of resection of the ends of DNA double strand breaks in yeast. Resection generates single-stranded tails that are vital for meiotic recombination. The Tel1 kinase promoted initiation of resection. Nucleosomes, which normally package DNA, needed to be disassembled to allow rapid and efficient resection.

Science, this issue p. 40

Abstract

DNA double-strand breaks that initiate meiotic recombination are exonucleolytically processed. This 5′→3′ resection is a central, conserved feature of recombination but remains poorly understood. To address this lack, we mapped resection endpoints genome-wide at high resolution in Saccharomyces cerevisiae. Full-length resection requires Exo1 exonuclease and the DSB-responsive kinase Tel1, but not Sgs1 helicase. Tel1 also promotes efficient and timely resection initiation. Resection endpoints display pronounced heterogeneity between genomic loci that reflects a tendency for nucleosomes to block Exo1, yet Exo1 also appears to digest chromatin with high processivity and at rates similar to naked DNA in vitro. This paradox points to nucleosome destabilization or eviction as a defining feature of the meiotic resection landscape.

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