Tetrameric Ctp1 coordinates DNA binding and DNA bridging in DNA double-strand-break repair.Andres, S.N., Appel, C.D., Westmoreland, J.W., Williams, J.S., Nguyen, Y., Robertson, P.D., Resnick, M.A., Williams, R.S.
(2015) Nat Struct Mol Biol 22: 158-166
- PubMed: 25580577
- DOI: https://doi.org/10.1038/nsmb.2945
- Primary Citation of Related Structures:
- PubMed Abstract:
Ctp1 (also known as CtIP or Sae2) collaborates with Mre11-Rad50-Nbs1 to initiate repair of DNA double-strand breaks (DSBs), but its functions remain enigmatic. We report that tetrameric Schizosaccharomyces pombe Ctp1 contains multivalent DNA-binding and DNA-bridging activities. Through structural and biophysical analyses of the Ctp1 tetramer, we define the salient features of Ctp1 architecture: an N-terminal interlocking tetrameric helical dimer-of-dimers (THDD) domain and a central intrinsically disordered region (IDR) linked to C-terminal 'RHR' DNA-interaction motifs. The THDD, IDR and RHR are required for Ctp1 DNA-bridging activity in vitro, and both the THDD and RHR are required for efficient DSB repair in S. pombe. Our results establish non-nucleolytic roles of Ctp1 in binding and coordination of DSB-repair intermediates and suggest that ablation of human CtIP DNA binding by truncating mutations underlie the CtIP-linked Seckel and Jawad syndromes.
Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA.