2022-04-082022-04-082022Canny, M. D., & Latham, M. P. (2022). LRET-derived haddock structural models describe the conformational heterogeneity required for DNA cleavage by the mre11-rad50 DNA damage repair complex. ELife, 11. https://doi.org/10.7554/elife.69579https://doi.org/10.7554/eLife.69579https://hdl.handle.net/2346/89094© 2022, Canny and Latham. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.The Mre11-Rad50-Nbs1 protein complex is one of the first responders to DNA double-strand breaks. Studies have shown that the catalytic activities of the evolutionarily conserved Mre11-Rad50 (MR) core complex depend on an ATP-dependent global conformational change that takes the macromolecule from an open, extended structure in the absence of ATP to a closed, globular structure when ATP is bound. We have previously identified an additional ‘partially open’ conformation using luminescence resonance energy transfer (LRET) experiments. Here, a combination of LRET and the molecular docking program HADDOCK was used to further investigate this partially open state and identify three conformations of MR in solution: closed, partially open, and open, which are in addition to the extended, apo conformation. Mutants disrupting specific Mre11-Rad50 interactions within each conformation were used in nuclease activity assays on a variety of DNA substrates to help put the three states into a functional perspective. LRET data collected on MR bound to DNA demonstrate that the three conformations also exist when nuclease substrates are bound. These models were further supported with small-angle X-ray scattering data, which corroborate the presence of multiple states in solution. Together, the data suggest a mechanism for the nuclease activity of the MR complex along the DNA.engBiochemistry and Chemical BiologyStructural Biology and Molecular BiophysicsP. furiosusMre11-Rad50Lanthanide Resonance Energy TransferDNA Damage RepairDNA Double-Strand Break RepairArticle