Cryo-EM study of start codon selection during archaeal translation initiation.
Fiche publication
Date publication
novembre 2016
Journal
Nature communications
Auteurs
Membres identifiés du Cancéropôle Est :
Dr KLAHOLZ Bruno
Tous les auteurs :
Coureux PD, Lazennec-Schurdevin C, Monestier A, Larquet E, Cladière L, Klaholz BP, Schmitt E, Mechulam Y
Lien Pubmed
Résumé
Eukaryotic and archaeal translation initiation complexes have a common structural core comprising e/aIF1, e/aIF1A, the ternary complex (TC, e/aIF2-GTP-Met-tRNA) and mRNA bound to the small ribosomal subunit. e/aIF2 plays a crucial role in this process but how this factor controls start codon selection remains unclear. Here, we present cryo-EM structures of the full archaeal 30S initiation complex showing two conformational states of the TC. In the first state, the TC is bound to the ribosome in a relaxed conformation with the tRNA oriented out of the P site. In the second state, the tRNA is accommodated within the peptidyl (P) site and the TC becomes constrained. This constraint is compensated by codon/anticodon base pairing, whereas in the absence of a start codon, aIF2 contributes to swing out the tRNA. This spring force concept highlights a mechanism of codon/anticodon probing by the initiator tRNA directly assisted by aIF2.
Mots clés
Anticodon, metabolism, Archaea, physiology, Archaeal Proteins, physiology, Base Pairing, physiology, Codon, Initiator, metabolism, Cryoelectron Microscopy, Peptide Chain Initiation, Translational, physiology, Peptide Initiation Factors, physiology, RNA, Messenger, metabolism, RNA, Transfer, Met, physiology, Ribosome Subunits, Small, Archaeal, physiology
Référence
Nat Commun. 2016 11 7;7:13366