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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