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Published August 21, 2020 | Version v1
Journal article Open

An ER translocon for multi-pass membrane protein biogenesis

Creators

  • 1. University of Chicago
  • 2. University of California, San Francisco

Description

Membrane proteins with multiple transmembrane domains play critical roles in cell physiology, but little is known about the machinery coordinating their biogenesis at the endoplasmic reticulum. Here we describe a ~360 kDa ribosome-associated complex comprising the core Sec61 channel and five accessory factors: TMCO1, CCDC47 and the Nicalin-TMEM147-NOMO complex. Cryo-electron microscopy reveals a large assembly at the ribosome exit tunnel organized around a central membrane cavity. Similar to protein-conducting channels that facilitate movement of transmembrane segments, cytosolic and luminal funnels in TMCO1 and TMEM147, respectively, suggest routes into the central membrane cavity. High-throughput mRNA sequencing shows selective translocon engagement with hundreds of different multi-pass membrane proteins. Consistent with a role in multi-pass membrane protein biogenesis, cells lacking different accessory components show reduced levels of one such client, the glutamate transporter EAAT1. These results identify a new human translocon and provide a molecular framework for understanding its role in multi-pass membrane protein biogenesis.

Data availability

Annotated spectra corresponding to the reported ribosome-translocon cross-links are available at the MS-Viewer website (http://msviewer.ucsf.edu/prospector/cgi-bin/msform.cgi?form=msviewer) with the following accession keys: HCD data: 7s2yb4zfjw and ETD data: vdibnsypj7. Cryo-EM maps have been deposited in the Electron Microscopy Data Bank with accession codes: EMD-21426 (Map 1), EMD-21427 (Map 2) and EMD-21435 (Map 3). Coordinates for the human 60S-translocon complex have been deposited in the Protein Data Bank with accession code 6W6L. mRNA sequencing data have been deposited in Gene Expression Omnibus (GEO) under accession number GSE134027.

The following data sets were generated:

McGilvray PT Anghel SA Sundaram A Zhong F Trnka MJ Fuller JR Hu H Burlingame AL Keenan RJ (2020) Electron Microscopy Data Bank ID EMD-21426. Single Particle Cryo-EM Structure of the Natively Isolated Sec61 complex, TMCO1, Nicalin, TMEM147, and CCDC47 Containing Translocon. https://www.ebi.ac.uk/pdbe/entry/emdb/EMD-21426

McGilvray PT Anghel SA Sundaram A Zhong F Trnka MJ Fuller JR Hu H Burlingame AL Keenan RJ (2020) Electron Microscopy Data Bank ID EMD-21427. Single Particle Cryo-EM Structure of the Natively Isolated Sec61 complex, TMCO1, Nicalin, TMEM147, and CCDC47 Containing Translocon. https://www.ebi.ac.uk/pdbe/entry/emdb/EMD-21427

McGilvray PT Anghel SA Sundaram A Zhong F Trnka MJ Fuller JR Hu H Burlingame AL Keenan RJ (2020) Electron Microscopy Data Bank ID EMD-21435. Single Particle Cryo-EM Structure of the Natively Isolated Sec61 complex, TMCO1, Nicalin, TMEM147, and CCDC47 Containing Translocon. https://www.ebi.ac.uk/pdbe/entry/emdb/EMD-21435

McGilvray PT Anghel SA Sundaram A Zhong F Trnka MJ Fuller JR Hu H Burlingame AL Keenan RJ (2020) RCSB Protein Data Bank ID 6W6L. Cryo-EM structure of the human ribosome-TMCO1 translocon. https://www.rcsb.org/structure/6W6L

McGilvray PT Anghel SA Sundaram A Zhong F Trnka MJ Fuller JR Hu H Burlingame AL Keenan RJ (2020) NCBI Gene Expression Omnibus ID GSE134027. mRNA sequencing data. http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE134027

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Additional details

Identifiers

DOI
10.7554/eLife.56889
Other
oai:uchicago.tind.io:9929

Funding

National Institute of General Medical Sciences
R01 GM130051
National Institutes of Health
vR21 EY026719
Boehringer Ingelheim Fonds
PhD fellowship
National Institute of General Medical Sciences
T32 GM007183
Adelson Medical Research Foundation
National Institutes of Health
R01 GM130051

UChicago Information

Division(s)
Biological Sciences Division
Department(s)
Biochemistry and Molecular Biology, Molecular Genetics and Cell Biology
Center(s) or Institute(s)
Center for Research Informatics