title: Structural basis for RNA unwinding by the DEAD-box protein Drosophila Vasa.
abstract: DEAD-box RNA helicases, which regulate various processes involving RNA, have two RecA-like domains as a catalytic core to alter higher-order RNA structures. We determined the 2.2 A resolution structure of the core of the Drosophila DEAD-box protein Vasa in complex with a single-stranded RNA and an ATP analog. The ATP analog intensively interacts with both of the domains, thereby bringing them into the closed form, with many interdomain interactions of conserved residues. The bound RNA is sharply bent, avoiding a clash with a conserved alpha helix in the N-terminal domain. This "wedge" helix should disrupt base pairs by bending one of the strands when a duplex is bound. Mutational analyses indicated that the interdomain interactions couple ATP hydrolysis to RNA unwinding, probably through fine positioning of the duplex relative to the wedge helix. This mechanism, which differs from those for canonical translocating helicases, may enable the targeted modulation of intricate RNA structures.
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Sengoku
authors.forename: Osamu
authors.initials: O
authors.lastname: Nureki
authors.forename: Akira
authors.initials: A
authors.lastname: Nakamura
authors.forename: Satoru
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D053487:DEAD-box RNA Helicases; D004252:DNA Mutational Analysis; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D020365:RNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D029721:Drosophila Proteins; D012313:RNA; D000255:Adenosine Triphosphate; C088269:vas protein, Drosophila; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases