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

DOI: 10.1038/s42003-020-0780-0

Authors: Pierre-damien Coureux (Ecole polytechnique, CNRS, Institut Polytechnique de Paris- Palaiseau) , Christine Lazennec-schurdevin (Ecole polytechnique, CNRS, Institut Polytechnique de Paris) , Sophie Bourcier (Ecole polytechnique, CNRS, Institut Polytechnique de Paris) , Yves Mechulam (Ecole polytechnique - Palaiseau) , Emmanuelle Schmitt (Ecole polytechnique, CNRS, Institut Polytechnique de Paris)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Communications Biology , VOL 3

State: Published (Approved)
Published: February 2020
Diamond Proposal Number(s): 16410

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.

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios II-Titan Krios II at Diamond

Documents:
s42003-020-0780-0.pdf