Interplay between Sae2 and Rif2 in the regulation of Mre11-Rad50 activities at DNA ends.

Diego Bonetti, Michela Clerici, Maria Pia Longhese

Current opinion in genetics & development 2021 Dec

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DNA double-strand breaks (DSBs) can be repaired by non-homologous end-joining (NHEJ) or homologous recombination (HR). HR is initiated by nucleolytic degradation of the DSB ends in a process termed resection. The Mre11-Rad50-Xrs2/NBS1 (MRX/N) complex is a multifunctional enzyme that, aided by the Sae2/CtIP protein, promotes DSB resection and maintains the DSB ends tethered to each other to facilitate their re-ligation. Furthermore, it activates the protein kinase Tel1/ATM, which initiates DSB signaling. In Saccharomyces cerevisiae, these MRX functions are inhibited by the Rif2 protein, which is enriched at telomeres and protects telomeric DNA from being sensed and processed as a DSB. The present review focuses on recent data showing that Sae2 and Rif2 regulate MRX functions in opposite manners by interacting with Rad50 and influencing ATP-dependent Mre11-Rad50 conformational changes. As Sae2 is enriched at DSBs whereas Rif2 is predominantly present at telomeres, the relative abundance of these two MRX regulators can provide an effective mechanism to activate or inactivate MRX depending on the nature of chromosome ends. Copyright © 2021 Elsevier Ltd. All rights reserved.

Citation

Diego Bonetti, Michela Clerici, Maria Pia Longhese. Interplay between Sae2 and Rif2 in the regulation of Mre11-Rad50 activities at DNA ends. Current opinion in genetics & development. 2021 Dec;71:72-77