5da9
ATP-gamma-S bound Rad50 from Chaetomium thermophilum in complex with the Rad50-binding domain of Mre11
Structural highlights
FunctionRAD50_CHATD Component of the MRN complex, which plays a central role in double-strand break (DSB) repair, DNA recombination, maintenance of telomere integrity and meiosis (By similarity). The MRN complex is involved in the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR), an error-free mechanism which primarily occurs during S and G2 phases (By similarity). The complex (1) mediates the end resection of damaged DNA, which generates proper single-stranded DNA, a key initial steps in HR, and is (2) required for the recruitment of other repair factors and efficient activation of ATM and ATR upon DNA damage (By similarity). The MRN complex possesses single-strand endonuclease activity and double-strand-specific 3'-5' exonuclease activity, which are provided by MRE11, to initiate end resection, which is required for single-strand invasion and recombination (By similarity). Within the complex, RAD50 is both required to bind DNA ends and hold them in close proximity and regulate the activity of MRE11 (PubMed:26896444, PubMed:36577401). RAD50 provides an ATP-dependent control of MRE11 by positioning DNA ends into the MRE11 active site: ATP-binding induces a large structural change from an open form with accessible MRE11 nuclease sites into a closed form (PubMed:36577401).[UniProtKB:Q92878][1] [2] Publication Abstract from PubMedThe Mre11-Rad50-Nbs1 (MRN) complex is a central factor in the repair of DNA double-strand breaks (DSBs). The ATP-dependent mechanisms of how MRN detects and endonucleolytically processes DNA ends for the repair by microhomology-mediated end-joining or further resection in homologous recombination are still unclear. Here, we report the crystal structures of the ATPgammaS-bound dimer of the Rad50NBD (nucleotide-binding domain) from the thermophilic eukaryote Chaetomium thermophilum (Ct) in complex with either DNA or CtMre11RBD (Rad50-binding domain) along with small-angle X-ray scattering and cross-linking studies. The structure and DNA binding motifs were validated by DNA binding experiments in vitro and mutational analyses in Saccharomyces cerevisiae in vivo. Our analyses provide a structural framework for the architecture of the eukaryotic Mre11-Rad50 complex. They show that a Rad50 dimer binds approximately 18 base pairs of DNA along the dimer interface in an ATP-dependent fashion or bridges two DNA ends with a preference for 3' overhangs. Finally, our results may provide a general framework for the interaction of ABC ATPase domains of the Rad50/SMC/RecN protein family with DNA. Structural mechanism of ATP-dependent DNA binding and DNA end bridging by eukaryotic Rad50.,Seifert FU, Lammens K, Stoehr G, Kessler B, Hopfner KP EMBO J. 2016 Feb 19. pii: e201592934. PMID:26896444[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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