Sae2, Exo1 and Sgs1 collaborate in DNA double-strand break processing

By Eleni P. Mimitou, L. Symington. Nature, 2008

1,082 citations recorded by the source corpus.

DNA ends exposed after introduction of double-strand breaks (DSBs) undergo 5′–3′ nucleolytic degradation to generate single-stranded DNA, the substrate for binding by the Rad51 protein to initiate homologous recombination. This process is poorly understood in eukaryotes, but several factors have been implicated, including the Mre11 complex (Mre11–Rad50–Xrs2/NBS1), Sae2/CtIP/Ctp1 and Exo1. Here we demonstrate that yeast Exo1 nuclease and Sgs1 helicase function in alternative pathways for DSB processing. Novel, partially resected intermediates accumulate in a double mutant lacking Exo1 and Sgs1, which are poor substrates for homologous recombination. The early processing step that generates partly resected intermediates is dependent on Sae2. When Sae2 is absent, in addition to Exo1 and Sgs1, unprocessed DSBs accumulate and homology-dependent repair fails. These results suggest a two-step mechanism for DSB processing during homologous recombination. First, the Mre11 complex and Sae2 remove a small oligonucleotide(s) from the DNA ends to form an early intermediate. Second, Exo1 and/or Sgs1 rapidly process this intermediate to generate extensive tracts of single-stranded DNA that serve as substrate for Rad51.

Subfields: Cancer Research, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/a7d5a897ac6a46a05527543140fdd74be7756a1b

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In Cancer Research

1. Wolf-Dietrich Heyer
2. L. Marácz
3. Xiaolan Zhao
4. L. Krejci
5. J. Petrini
6. M. Moynahan
7. M. Jasin
8. M. Špírek

In Molecular Biology

1. M. Moynahan
2. M. Jasin
3. Claire Wyman
4. Wolf-Dietrich Heyer
5. Jie Liu
6. L. Marácz
7. Xiaolan Zhao
8. L. Krejci

Citations in the corpus

• Systematic identification of cell cycle-dependent yeast nucleocytoplasmic shuttling proteins by prediction of composite motifs (2009, background): “Dna2 resects DNA double-strand-break ends in concert with other helicase and nucleases including Sae2 (34), which is regulated by CDK1 (35).”
• Regulation of homologous recombination in eukaryotes (2010, background): “Extended resection is achieved by the 5 → 3 exonuclease activity of Exo1 or the helicase activity of Sgs1 in cooperation with the endonuclease activity of Dna2 (103, 173).”
• Chapter 1. General introduction (2015, positive): “After this initial processing of the DSB resection, it is taken over by the exonuclease (Exo1) and the Sgs1 helicase (20).”
• Homologous recombination and its regulation (2012, background): “We note that Sgs1 can also indirectly promote Rad51 filament formation by generation of 30-overhangs during end processing (102,112).”
• Mitotic homologous recombination maintains genomic stability and suppresses tumorigenesis (2010, positive): “Limited resection involves the Mre11 complex and Sae2; more extensive resection involves either exodeoxyribonuclease 1 (Exo1; a 5′ to 3′ exonuclease) or the Sgs1 helicase (which unwinds duplex DNA) together with a nuclease to digest the 5′ stran”
• BLM-DNA2-RPA-MRN and EXO1-BLM-RPA-MRN constitute two DNA end resection machineries for human DNA break repair. (2011, background): “In the physical absence of MRX, resection is kinetically delayed (Mimitou and Symington 2008; Zhu et al. 2008), whereas in the nuclease-deficient strain, there is no delay (Llorente and Symington 2004).”
• The MRE11 complex: starting from the ends (2011, positive): “This initial resection is followed by the bulk resection of DNA by either the 5′–3′ exonuclease 1 (Exo1) or DNA2 in conjunction with the helicase Sgs1 (Ref”