Structural basis for DNA break sensing by human MRE11-RAD50-NBS1 and its regulation by telomeric factor TRF2

Fan, Yilan; Kuybu, Filiz; Cui, Hengjun; Lammens, Katja; Chen, Jia-Xuan; Kugler, Michael; Jung, Christophe; Hopfner, Karl-Peter (2025): Structural basis for DNA break sensing by human MRE11-RAD50-NBS1 and its regulation by telomeric factor TRF2. Nature Communications, 16: 8320. ISSN 2041-1723

Abstract

The MRE11-RAD50-NBS1 (MRN) complex is a central, multifunctional factor in the detection, signaling and nucleolytic processing of DNA double-strand breaks (DSBs). To clarify how human MRN binds generic and telomeric DNA ends and can separate DNA end sensing from nuclease activities, we determined cryo-electron microscopy (cryo-EM) structures of human MRN bound to DNA and to DNA and the telomere protection factor TRF2. MRN senses DSBs through a tight clamp-like sensing state with closed coiled-coil domains, but auto-inhibited MRE11 nuclease. NBS1 wraps around the MRE11 dimer, with NBS1’s ATM recruitment motif sequestered by binding to the regulatory RAD50 S site, necessitating a switch in the NBS1 C helix for ATM activation. At telomeric DNA, TRF2 blocks the second S site via the iDDR motif to prevent nuclease and ATM activation. Our results provide a structural framework for DNA sensing via a gating mechanism and separation of sensing, signaling and processing activities of mammalian MRN.

• Dokumententyp: Artikel (LMU)
• Organisationseinheit (Fakultäten): 18 Chemie und Pharmazie > GenZentrum
• DFG-Fachsystematik der Wissenschaftsbereiche: Naturwissenschaften
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 393547839
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892