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Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation

Abstract : Archaeal translation initiation occurs within a macromolecular complex containing the small ribosomal subunit (30S) bound to mRNA, initiation factors aIF1, aIF1A and the ternary complex aIF2:GDPNP:Met-tRNAiMet. Here, we determine the cryo-EM structure of a 30S:mRNA:aIF1A:aIF2:GTP:Met-tRNAiMet complex from Pyrococcus abyssi at 3.2 Å resolution. It highlights archaeal features in ribosomal proteins and rRNA modifications. We find an aS21 protein, at the location of eS21 in eukaryotic ribosomes. Moreover, we identify an N-terminal extension of archaeal eL41 contacting the P site. We characterize 34 N4-acetylcytidines distributed throughout 16S rRNA, likely contributing to hyperthermostability. Without aIF1, the 30S head is stabilized and initiator tRNA is tightly bound to the P site. A network of interactions involving tRNA, mRNA, rRNA modified nucleotides and C-terminal tails of uS9, uS13 and uS19 is observed. Universal features and domain-specific idiosyncrasies of translation initiation are discussed in light of ribosomal structures from representatives of each domain of life.
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https://hal-polytechnique.archives-ouvertes.fr/hal-02493692
Contributor : Aurélien Arnoux <>
Submitted on : Friday, February 28, 2020 - 9:22:33 AM
Last modification on : Wednesday, July 29, 2020 - 4:23:15 PM

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Pierre-Damien Coureux, Christine Lazennec-Schurdevin, Sophie Bourcier, Yves Mechulam, Emmanuelle Schmitt. Cryo-EM study of an archaeal 30S initiation complex gives insights into evolution of translation initiation. Communications Biology, Nature Publishing Group, 2020, 3 (1), ⟨10.1038/s42003-020-0780-0⟩. ⟨hal-02493692⟩

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