The molecular structure of the left-handed supra-molecular helix of eukaryotic polyribosomes.
Fiche publication
Date publication
novembre 2014
Journal
Nature communications
Auteurs
Membres identifiés du Cancéropôle Est :
Dr KLAHOLZ Bruno
Tous les auteurs :
Myasnikov AG, Afonina ZA, Ménétret JF, Shirokov VA, Spirin AS, Klaholz BP
Lien Pubmed
Résumé
During protein synthesis, several ribosomes bind to a single messenger RNA (mRNA) forming large macromolecular assemblies called polyribosomes. Here we report the detailed molecular structure of a 100 MDa eukaryotic poly-ribosome complex derived from cryo electron tomography, sub-tomogram averaging and pseudo-atomic modelling by crystal structure fitting. The structure allowed the visualization of the three functional parts of the polysome assembly, the central core region that forms a rather compact left-handed supra-molecular helix, and the more open regions that harbour the initiation and termination sites at either ends. The helical region forms a continuous mRNA channel where the mRNA strand bridges neighbouring exit and entry sites of the ribosomes and prevents mRNA looping between ribosomes. This structure provides unprecedented insights into protein- and RNA-mediated inter-ribosome contacts that involve conserved sites through 40S subunits and long protruding RNA expansion segments, suggesting a role in stabilizing the overall polyribosomal assembly.
Mots clés
Cryoelectron Microscopy, Eukaryotic Cells, Molecular Conformation, Plasmids, Polyribosomes, chemistry, RNA, Messenger, chemistry, RNA, Ribosomal, chemistry, Triticum
Référence
Nat Commun. 2014 Nov 7;5:5294