Abstract
Homologous recombination repairs DNA double-strand breaks (DSB) using an intact dsDNA molecule as a template. It entails a homology search step, carried out along a conserved RecA/Rad51-ssDNA filament assembled on each DSB end. Whether, how and to what extent a DSB impacts chromatin folding, and how this (re)organization in turns influences the homology search process, remain ill-defined. Here we characterize two layers of spatial chromatin reorganization following DSB formation in Saccharomyces cerevisiae. Although cohesin folds chromosomes into cohesive arrays of ~20-kb-long chromatin loops as cells arrest in G2/M, the DSB-flanking regions interact locally in a resection- and 9-1-1 clamp-dependent manner, independently of cohesin, Mec1ATR, Rad52 and Rad51. This local structure blocks cohesin progression, constraining the DSB region at the base of a loop. Functionally, cohesin promotes DSB-dsDNA interactions and donor identification in cis, while inhibiting them in trans. This study identifies multiple direct and indirect ways by which cohesin regulates homology search during recombinational DNA repair.
© 2021. The Author(s), under exclusive licence to Springer Nature Limited.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Chromatin / genetics
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Chromatin / metabolism*
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Chromatin Assembly and Disassembly*
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism*
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Cohesins
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DNA Breaks, Double-Stranded*
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DNA, Fungal / genetics
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DNA, Fungal / metabolism*
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Gene Expression Regulation, Fungal
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism
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Mutation
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism
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Rad51 Recombinase / genetics
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Rad51 Recombinase / metabolism
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Rad52 DNA Repair and Recombination Protein / genetics
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Rad52 DNA Repair and Recombination Protein / metabolism
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Recombinational DNA Repair*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
Substances
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Cell Cycle Proteins
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Chromatin
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Chromosomal Proteins, Non-Histone
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DNA, Fungal
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Intracellular Signaling Peptides and Proteins
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RAD52 protein, S cerevisiae
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Rad52 DNA Repair and Recombination Protein
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Saccharomyces cerevisiae Proteins
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MEC1 protein, S cerevisiae
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Protein Serine-Threonine Kinases
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RAD51 protein, S cerevisiae
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Rad51 Recombinase