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Stepwise 5' DNA end-specific resection of DNA breaks by the Mre11-Rad50-Xrs2 and Sae2 nuclease ensemble

  • Cannavo, Elda Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland
  • Reginato, Giordano Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland - Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
  • Cejka, Petr Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland - Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
    28.02.2019
Published in:
  • Proceedings of the national academy of sciences of the United States of America. - 2019, vol. 116, no. 12 (March 19), p. 5505-5513
DNA
nuclease
homologous recombination
Mre11
DNA end resection
English To repair DNA double-strand breaks by homologous recombination, the 5′-terminated DNA strands must first be resected to produce 3′ overhangs. Mre11 from Saccharomyces cerevisiae is a 3′ → 5′ exonuclease that is responsible for 5′ end degradation in vivo. Using plasmid-length DNA substrates and purified recombinant proteins, we show that the combined exonuclease and endonuclease activities of recombinant MRX-Sae2 preferentially degrade the 5′-terminated DNA strand, which extends beyond the vicinity of the DNA end. Mechanistically, Rad50 restricts the Mre11 exonuclease in an ATP binding-dependent manner, preventing 3′ end degradation. Phosphorylated Sae2, along with stimulating the MRX endonuclease as shown previously, also overcomes this inhibition to promote the 3′ → 5′ exonuclease of MRX, which requires ATP hydrolysis by Rad50. Our results support a model in which MRX-Sae2 catalyzes 5′-DNA end degradation by stepwise endonucleolytic DNA incisions, followed by exonucleolytic 3′ → 5′ degradation of the individual DNA fragments. This model explains how both exonuclease and endonuclease activities of Mre11 functionally integrate within the MRX-Sae2 ensemble to resect 5′-terminated DNA.
Language
  • English
Classification
Biology, life sciences
License
License undefined
Open access status
green
Identifiers
  • RERO DOC 324587
  • ARK ark:/12658/srd1318860
Persistent URL
https://n2t.net/ark:/12658/srd1318860
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