Nature Structural & Molecular Biology
- 13, 1092 - 1096 (2006)
Published online: 19 November 2006; | doi:10.1038/nsmb1177
Structure of the ribosome-bound cricket paralysis virus IRES RNAMartin Schüler1, Sean R Connell1, Aurelie Lescoute2, Jan Giesebrecht1, Marylena Dabrowski1, Birgit Schroeer1, Thorsten Mielke3, Pawel A Penczek4, Eric Westhof2 & Christian M T Spahn11
Institut für Medizinische Physik und Biophysik, Charite-Universitätsmedizin Berlin, Ziegelstrasse 5-9, 10117-Berlin, Germany. 2
Architecture et Réactivité de l'ARN, Université Louis Pasteur, Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, 15 rue R. Descartes, F-67084 Strasbourg, France. 3
UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195-Berlin, Germany. 4
The University of Texas-Houston Medical School, 6431 Fannin, Houston, Texas 77030, USA.
Correspondence should be addressed to Christian M T Spahn christian.spahn@charite.de Internal ribosome entry sites (IRESs) facilitate an alternative, end-independent pathway of translation initiation. A particular family of dicistroviral IRESs can assemble elongation-competent 80S ribosomal complexes in the absence of canonical initiation factors and initiator transfer RNA. We present here a cryo-EM reconstruction of a dicistroviral IRES bound to the 80S ribosome. The resolution of the cryo-EM reconstruction, in the subnanometer range, allowed the molecular structure of the complete IRES in its active, ribosome-bound state to be solved. The structure, harboring three pseudoknot-containing domains, each with a specific functional role, shows how defined elements of the IRES emerge from a compactly folded core and interact with the key ribosomal components that form the A, P and E sites, where tRNAs normally bind. Our results exemplify the molecular strategy for recruitment of an IRES and reveal the dynamic features necessary for internal initiation.
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