title: Cooperative binding of ATP and RNA induces a closed conformation in a DEAD box RNA helicase.
abstract: RNA helicases couple the energy from ATP hydrolysis with structural changes of their RNA substrates. DEAD box helicases form the largest class of RNA helicases and share a helicase core comprising two RecA-like domains. An opening and closing of the interdomain cleft during RNA unwinding has been postulated but not shown experimentally. Single-molecule FRET experiments with the Bacillus subtilis DEAD box helicase YxiN carrying donor and acceptor fluorophores on different sides of the interdomain cleft reveal an open helicase conformation in the absence of nucleotides, or in the presence of ATP, or ADP, or RNA. In the presence of ADP and RNA, the open conformation is retained. By contrast, cooperative binding of ATP and RNA leads to a compact helicase structure, proving that the ATP- and ADP-bound states of RNA helicases display substantially different structures only when the RNA substrate is bound. These results establish a closure of the interdomain cleft in the helicase core at the beginning of the unwinding reaction, and suggest a conserved mechanism of energy conversion among DEAD box helicases across kingdoms.
authors.affiliation: Department of Biophysical Chemistry, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
authors.forename: Bettina
authors.initials: B
authors.lastname: Theissen
authors.forename: Anne R
authors.initials: AR
authors.lastname: Karow
authors.forename: Jürgen
authors.initials: J
authors.lastname: Köhler
authors.forename: Airat
authors.initials: A
authors.lastname: Gubaev
authors.forename: Dagmar
authors.initials: D
authors.lastname: Klostermeier
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry*; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D003545:Cysteine / Q000737:chemistry; D053487:DEAD-box RNA Helicases / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D006868:Hydrolysis; D007700:Kinetics; D008024:Ligands; D008968:Molecular Conformation; D009691:Nucleic Acid Denaturation; D011485:Protein Binding; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D012313:RNA; C401542:yxiN protein, Bacillus subtilis; D053487:DEAD-box RNA Helicases; D003545:Cysteine