title: Structural model of full-length human Ku70-Ku80 heterodimer and its recognition of DNA and DNA-PKcs.
abstract: Recognition of DNA double-strand breaks during non-homologous end joining is carried out by the Ku70-Ku80 protein, a 150 kDa heterodimer that recruits the DNA repair kinase DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to the lesion. The atomic structure of a truncated Ku70-Ku80 was determined; however, the subunit-specific carboxy-terminal domain of Ku80--essential for binding to DNA-PKcs--was determined only in isolation, and the C-terminal domain of Ku70 was not resolved in its DNA-bound conformation. Both regions are conserved and mediate protein-protein interactions specific to mammals. Here, we reconstruct the three-dimensional structure of the human full-length Ku70-Ku80 dimer at 25 A resolution, alone and in complex with DNA, by using single-particle electron microscopy. We map the C-terminal regions of both subunits, and their conformational changes after DNA and DNA-PKcs binding to define a molecular model of the functions of these domains during DNA repair in the context of full-length Ku70-Ku80 protein.
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Spanish National Research Council (CSIC), Ramiro de Maeztu 9, Campus Complutense University, Madrid 28040, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Rivera-Calzada
authors.forename: Laura
authors.initials: L
authors.lastname: Spagnolo
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Pearl
authors.forename: Oscar
authors.initials: O
authors.lastname: Llorca
mesh_terms: D034961:Antigens, Nuclear / Q000737:chemistry* / Q000648:ultrastructure*; D004247:DNA / Q000737:chemistry*; D051747:DNA-Activated Protein Kinase / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D019281:Dimerization; D006801:Humans; D000072200:Ku Autoantigen; D008854:Microscopy, Electron; D011487:Protein Conformation; D025941:Protein Interaction Mapping
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D004247:DNA; D051747:DNA-Activated Protein Kinase; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen