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Science. 2016 Dec 16;354(6318):1431-1433.

The cryo-EM structure of a ribosome-Ski2-Ski3-Ski8 helicase complex.

Author information

1
Gene Center and Center for Integrated Protein Science Munich, Department of Biochemistry, Feodor-Lynen-Strasse 25, University of Munich, 81377 Munich, Germany.
2
Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, 82152 Martinsried, Munich, Germany.
3
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.
4
Sorbonne Universités, UPMC Paris 6, Complexité du Vivant, 75252 Paris Cedex 05, France.
5
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.
6
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.

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.

PMID:
27980209
DOI:
10.1126/science.aaf7520
[Indexed for MEDLINE]

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