title: The cryo-EM structure of a ribosome-Ski2-Ski3-Ski8 helicase complex.
abstract: Ski2-Ski3-Ski8 (Ski) is a helicase complex functioning with the RNA-degrading exosome to mediate the 3'-5' messenger RNA (mRNA) decay in turnover and quality-control pathways. We report that the Ski complex directly associates with 80S ribosomes presenting a short mRNA 3' overhang. We determined the structure of an endogenous ribosome-Ski complex using cryo-electron microscopy (EM) with a local resolution of the Ski complex ranging from 4 angstroms (Å) in the core to about 10 Å for intrinsically flexible regions. Ribosome binding displaces the autoinhibitory domain of the Ski2 helicase, positioning it in an open conformation near the ribosomal mRNA entry tunnel. We observe that the mRNA 3' overhang is threaded directly from the small ribosomal subunit to the helicase channel of Ski2, primed for ongoing exosome-mediated 3'-5' degradation.
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schmidt
authors.affiliation: Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, 82152 Martinsried, Munich, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Kowalinski
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: Vivekanandan
authors.initials: V
authors.lastname: Shanmuganathan
authors.affiliation: Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3525, Rue du Docteur Roux 25-28, 75724 Paris, France.|Sorbonne Universités, UPMC Paris 6, Complexité du Vivant, 75252 Paris Cedex 05, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Defenouillère
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Braunger
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Heuer
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Pech
authors.affiliation: Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3525, Rue du Docteur Roux 25-28, 75724 Paris, France.
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Namane
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
authors.forename: Otto
authors.initials: O
authors.lastname: Berninghausen
authors.affiliation: Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3525, Rue du Docteur Roux 25-28, 75724 Paris, France.
authors.forename: Micheline
authors.initials: M
authors.lastname: Fromont-Racine
authors.affiliation: Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3525, Rue du Docteur Roux 25-28, 75724 Paris, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Jacquier
authors.affiliation: Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, 82152 Martinsried, Munich, Germany. beckmann@genzentrum.lmu.de becker@genzentrum.lmu.de conti@biochem.mpg.de.
authors.forename: Elena
authors.initials: E
authors.lastname: Conti
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany. beckmann@genzentrum.lmu.de becker@genzentrum.lmu.de conti@biochem.mpg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Becker
authors.affiliation: Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany. beckmann@genzentrum.lmu.de becker@genzentrum.lmu.de conti@biochem.mpg.de.
authors.forename: Roland
authors.initials: R
authors.lastname: Beckmann
mesh_terms: D020285:Cryoelectron Microscopy; D004265:DNA Helicases / Q000648:ultrastructure*; D063326:Exosome Multienzyme Ribonuclease Complex / Q000648:ultrastructure*; D009687:Nuclear Proteins / Q000648:ultrastructure*; D011487:Protein Conformation; D020871:RNA Stability; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000201:enzymology / Q000648:ultrastructure*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000648:ultrastructure*
chemical_list: D009687:Nuclear Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D012335:RNA, Ribosomal; C081929:SKI2 protein, S cerevisiae; C406671:SKI3 protein, S cerevisiae; C079882:SKI8 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D063326:Exosome Multienzyme Ribonuclease Complex; D004265:DNA Helicases