1. DNA Double-Strand Break Repair Pathway Choice Is Directed by Distinct MRE11 Nuclease Activities.
- Author
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Shibata, Atsushi, Moiani, Davide, Arvai, Andrew?S., Perry, Jefferson, Harding, Shane?M., Genois, Marie-Michelle, Maity, Ranjan, van?Rossum-Fikkert, Sari, Kertokalio, Aryandi, Romoli, Filippo, Ismail, Amani, Ismalaj, Ermal, Petricci, Elena, Neale, Matthew?J., Bristow, Robert?G., Masson, Jean-Yves, Wyman, Claire, Jeggo, Penny?A., and Tainer, John?A.
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DNA repair , *NUCLEASES , *GENETIC recombination , *CHEMICAL libraries , *EXONUCLEASES , *ENZYME inhibitors - Abstract
Summary: MRE11 within the MRE11-RAD50-NBS1 (MRN) complex acts in DNA double-strand break repair (DSBR), detection, and signaling; yet, how its endo- and exonuclease activities regulate DSBR by nonhomologous end-joining (NHEJ) versus homologous recombination (HR) remains enigmatic. Here, we employed structure-based design with a focused chemical library to discover specific MRE11 endo- or exonuclease inhibitors. With these inhibitors, we examined repair pathway choice at DSBs generated in G2 following radiation exposure. While nuclease inhibition impairs radiation-induced replication protein A (RPA) chromatin binding, suggesting diminished resection, the inhibitors surprisingly direct different repair outcomes. Endonuclease inhibition promotes NHEJ in lieu of HR, while exonuclease inhibition confers a repair defect. Collectively, the results describe nuclease-specific MRE11 inhibitors, define distinct nuclease roles in DSB repair, and support a mechanism whereby MRE11 endonuclease initiates resection, thereby licensing HR followed by MRE11 exonuclease and EXO1/BLM bidirectional resection toward and away from the DNA end, which commits to HR. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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