Cryo-EM Study of Start Codon Selection During Archaeal Translation Initiation

Overview

Journal Nat Commun

Specialty Biology

Date 2016 Nov 8

PMID 27819266

Citations 16

Authors

Pierre-Damien Coureux

Christine Lazennec-Schurdevin

Auriane Monestier

Eric Larquet

Lionel Cladiere

Bruno P Klaholz

Emmanuelle Schmitt

Yves Mechulam

Affiliations

Soon will be listed here.

Abstract

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.

Citing Articles

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