EMD-8148

Single-particle
5.34 Å
EMD-8148 Deposition: 13/04/2016
Map released: 30/11/2016
Last modified: 09/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-8148

Cryo-EM structure of a full archaeal ribosomal translation initiation complex in the P-REMOTE conformation

EMD-8148

Single-particle
5.34 Å
EMD-8148 Deposition: 13/04/2016
Map released: 30/11/2016
Last modified: 09/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Pyrococcus abyssi GE5, Escherichia coli
Sample: 30S archaeal translation initiation complex
Fitted models: 5jb3 (Avg. Q-score: 0.164)

Deposition Authors: COUREUX P-D, SCHMITT E
Cryo-EM study of start codon selection during archaeal translation initiation.
PUBMED: 27819266
DOI: doi:10.1038/ncomms13366
ISSN: 2041-1723
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-tRNAiMet) 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.