title: Tetrameric Ctp1 coordinates DNA binding and DNA bridging in DNA double-strand-break repair.
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.
authors.affiliation: 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.
authors.forename: Sara N
authors.initials: SN
authors.lastname: Andres
authors.affiliation: 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.
authors.forename: C Denise
authors.initials: CD
authors.lastname: Appel
authors.affiliation: 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.
authors.forename: James W
authors.initials: JW
authors.lastname: Westmoreland
authors.affiliation: 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.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Williams
authors.affiliation: 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.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nguyen
authors.affiliation: 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.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Robertson
authors.affiliation: 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.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Resnick
authors.affiliation: 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.
authors.forename: R Scott
authors.initials: RS
authors.lastname: Williams
mesh_terms: D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization / Q000502:physiology*; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C525888:Ctp1 protein, S pombe; D004268:DNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins