Abstract
DNA double-strand break repair by homologous recombination is initiated by DNA end resection, which is commenced by the Mre11-Rad50-Xrs2 complex and Sae2 in yeast. Here we report that the nonhomologous end joining factor Ku limits the exonuclease activity of Mre11 and promotes its endonuclease to cleave 5'-terminated DNA strands at break sites. Following initial endonucleolytic cleavage past the obstacle, Exo1 specifically extends the resection track, leading to the generation of long 3' overhangs that are required for homologous recombination. These experiments provide mechanistic insights into how short-range and long-range DNA end resection enzymes overcome obstacles near broken DNA ends to initiate recombination.
Keywords:
DNA end resection; DNA nuclease; Ku70–80; Sae2; homologous recombination; yMre11.
© 2018 Reginato et al.; Published by Cold Spring Harbor Laboratory Press.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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DNA Cleavage
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DNA End-Joining Repair*
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DNA-Binding Proteins / metabolism
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Endodeoxyribonucleases / metabolism
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Endonucleases / metabolism*
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Enzyme Activation / genetics
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Exodeoxyribonucleases / metabolism
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Exonucleases / metabolism*
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Multiprotein Complexes / metabolism
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Sf9 Cells
Substances
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DNA-Binding Proteins
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Multiprotein Complexes
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RAD50 protein, S cerevisiae
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SAE2 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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XRS2 protein, S cerevisiae
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high affinity DNA-binding factor, S cerevisiae
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Endodeoxyribonucleases
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Endonucleases
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Exodeoxyribonucleases
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Exonucleases
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MRE11 protein, S cerevisiae
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exodeoxyribonuclease I