title: Single-particle image reconstruction of a tetramer of HIV integrase bound to DNA.
abstract: The HIV integrase enzyme (IN) catalyzes the initial DNA breaking and joining reactions that integrate viral DNA in the host chromosome. Structures for individual IN domains have been determined by X-ray crystallography and NMR spectroscopy, but the structure of the complete IN-DNA complex has remained elusive. Homogeneous complexes of IN tetramers were assembled on DNA three-way junction substrates designed to resemble integration intermediates. Electron microscopy and single-particle image analysis of these complexes yielded a three-dimensional reconstruction at approximately 27 A resolution. The map of the IN-DNA complex displays four lobes of density approximately 50 A in diameter. Three of the lobes form a roughly triangular base with a central channel approximately 20 A in diameter. The fourth lobe is centered between two lobes and extends approximately 40 A above the base. We propose that the central channel tethers the target DNA, and two of the lobes may bind the ends of the viral DNA. The asymmetry of the complex is a feature not incorporated in previous structural models and potentially provides the first view of an asymmetric reaction intermediate.
authors.affiliation: The Scripps Research Institute, Department of Cell Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Ren
authors.forename: Kui
authors.initials: K
authors.lastname: Gao
authors.forename: Frederic D
authors.initials: FD
authors.lastname: Bushman
authors.forename: Mark
authors.initials: M
authors.lastname: Yeager
mesh_terms: D001483:Base Sequence; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry; D019427:HIV Integrase / Q000737:chemistry* / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012995:Solubility; D013329:Structure-Activity Relationship; D016662:Virus Integration
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; D019427:HIV Integrase