Visualization of translation and protein biogenesis at the ER membrane.

Autor: Gemmer M; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Chaillet ML; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., van Loenhout J; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Cuevas Arenas R; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Vismpas D; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Gröllers-Mulderij M; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Koh FA; Thermo Fisher Scientific, Eindhoven, The Netherlands., Albanese P; Biomolecular Mass Spectrometry and Proteomics Group, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.; Netherlands Proteomics Center, Utrecht University, Utrecht University, Utrecht, The Netherlands., Scheltema RA; Biomolecular Mass Spectrometry and Proteomics Group, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.; Netherlands Proteomics Center, Utrecht University, Utrecht University, Utrecht, The Netherlands., Howes SC; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands., Kotecha A; Thermo Fisher Scientific, Eindhoven, The Netherlands., Fedry J; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands. j.m.m.fedry@uu.nl., Förster F; Structural Biochemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands. f.g.forster@uu.nl.
Jazyk: angličtina
Zdroj: Nature [Nature] 2023 Feb; Vol. 614 (7946), pp. 160-167. Date of Electronic Publication: 2023 Jan 25.
DOI: 10.1038/s41586-022-05638-5
Abstrakt: The dynamic ribosome-translocon complex, which resides at the endoplasmic reticulum (ER) membrane, produces a major fraction of the human proteome 1,2 . It governs the synthesis, translocation, membrane insertion, N-glycosylation, folding and disulfide-bond formation of nascent proteins. Although individual components of this machinery have been studied at high resolution in isolation 3-7 , insights into their interplay in the native membrane remain limited. Here we use cryo-electron tomography, extensive classification and molecular modelling to capture snapshots of mRNA translation and protein maturation at the ER membrane at molecular resolution. We identify a highly abundant classical pre-translocation intermediate with eukaryotic elongation factor 1a (eEF1a) in an extended conformation, suggesting that eEF1a may remain associated with the ribosome after GTP hydrolysis during proofreading. At the ER membrane, distinct polysomes bind to different ER translocons specialized in the synthesis of proteins with signal peptides or multipass transmembrane proteins with the translocon-associated protein complex (TRAP) present in both. The near-complete atomic model of the most abundant ER translocon variant comprising the protein-conducting channel SEC61, TRAP and the oligosaccharyltransferase complex A (OSTA) reveals specific interactions of TRAP with other translocon components. We observe stoichiometric and sub-stoichiometric cofactors associated with OSTA, which are likely to include protein isomerases. In sum, we visualize ER-bound polysomes with their coordinated downstream machinery.
(© 2023. The Author(s).)
Databáze: MEDLINE
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