EMD-8149
Cryo-EM structure of a full archaeal ribosomal translation initiation complex in the P-INconformation
EMD-8149
Single-particle5.34 Å
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Map released: 07/12/2016
Last modified: 12/06/2024
Sample Organism:
Pyrococcus abyssi GE5,
Escherichia coli,
Pyrococcus
Sample: 30S archaeal translation initiation complex
Fitted models: 5jbh (Avg. Q-score: 0.117)
Deposition Authors: COUREUX P-D, SCHMITT E
Sample: 30S archaeal translation initiation complex
Fitted models: 5jbh (Avg. Q-score: 0.117)
Deposition Authors: COUREUX P-D, SCHMITT E
Cryo-EM study of start codon selection during archaeal translation initiation.
Coureux PD,
Lazennec-Schurdevin C,
Monestier A,
Larquet E,
Cladiere L,
Klaholz BP,
Schmitt E,
Mechulam Y
(2016) Nat Commun , 7 , 13366 - 13366
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(2016) Nat Commun , 7 , 13366 - 13366
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.
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.