Ku protein

Structure of the Ku heterodimer bound to DNA

spinqualitylabelsall models Structure of the Ku heterodimer bound to DNA (PDB entry 1JEY) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D PubMed 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. Ku Ring Ku Ring Instead of most DNA binding proteins, the Ku heterodimer contains a ring that encircles the DNA helix, with preference towards DNA ends. By binding to the DNA end, the Ku ring protects the broken DNA strands from degradation and from base pairing to another DNA strand. Domains Ku70 Dimer α/β-Domain β-barrel C-terminal arm DNA binding ring

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