MRE11 deacetylation by SIRT2 promotes DNA binding to facilitate DNA end resection and ATM-dependent signaling.

MRE11, a breast tumor suppressor and component of the MRE11-RAD50-NBS1 complex, plays a critical role in DNA end resection and initiation of ataxia-telangiectasia mutation-dependent (ATM-dependent) DNA damage signaling. However, the precise mechanisms governing MRE11 function in the DNA damage response (DDR) remain incompletely understood. Here, we found that MRE11 is deacetylated by the SIRT2 sirtuin deacetylase and breast tumor suppressor, which promotes DNA binding to facilitate DNA end resection and ATM-dependent signaling. SIRT2 deacetylase activity promoted DNA end resection. SIRT2 further complexed with and deacetylated MRE11 at conserved lysine 393 (K393) in response to DNA double-stranded breaks (DSBs), which promoted MRE11 localization and DNA binding at DSBs but not interaction with RAD50, NBS1, or CtIP. Moreover, MRE11 K393 deacetylation by SIRT2 promoted ATM-dependent signaling. Our findings define a mechanism regulating MRE11 binding to DNA through SIRT2 deacetylation, elucidating a critical upstream signaling event directing MRE11 function in the DDR and providing insight into how SIRT2 dysregulation leads to genomic instability and tumorigenesis.