Structure of the Ku Heterodimer Bound to DNA and Its Implications for Double-Strand Break Repair

Nature. 2001 Aug 9;412(6847):607-14. doi: 10.1038/35088000.

Abstract

The Ku heterodimer (Ku70 and Ku80 subunits) contributes to genomic integrity through its ability to bind DNA double-strand breaks and facilitate repair by the non-homologous end-joining pathway. The crystal structure of the human Ku heterodimer was determined both alone and bound to a 55-nucleotide DNA element at 2.7 and 2.5 A resolution, respectively. Ku70 and Ku80 share a common topology and form a dyad-symmetrical molecule with a preformed ring that encircles duplex DNA. The binding site can cradle two full turns of DNA while encircling only the central 3-4 base pairs (bp). Ku makes no contacts with DNA bases and few with the sugar-phosphate backbone, but it fits sterically to major and minor groove contours so as to position the DNA helix in a defined path through the protein ring. These features seem well designed to structurally support broken DNA ends and to bring the DNA helix into phase across the junction during end processing and ligation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Antigens, Nuclear*
  • Crystallography, X-Ray
  • DNA / chemistry
  • DNA / metabolism*
  • DNA Helicases*
  • DNA Repair*
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology
  • Humans
  • Ku Autoantigen
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / physiology
  • Nucleic Acid Conformation
  • Protein Binding
  • Protein Conformation
  • Recombinant Proteins / chemistry
  • Sequence Alignment

Substances

  • Antigens, Nuclear
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Recombinant Proteins
  • DNA
  • DNA Helicases
  • XRCC5 protein, human
  • Xrcc6 protein, human
  • Ku Autoantigen

Associated data

  • PDB/1JEQ
  • PDB/1JEY