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    Sub-tomogram averaging of COPII assemblies reveals how coat organization dictates membrane shape

    Hutchings, J. and Stancheva, V. and Miller, E.A. and Zanetti, Giulia (2018) Sub-tomogram averaging of COPII assemblies reveals how coat organization dictates membrane shape. Nature Communications 9 (4154), ISSN 2041-1723.

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    Eukaryotic cells employ membrane-bound carriers to transport cargo between compartments in a process essential to cell functionality. Carriers are generated by coat complexes that couple cargo capture to membrane deformation. The COPII coat mediates export from the endoplasmic reticulum by assembling in inner and outer layers, yielding carriers of variable shape and size that allow secretion of thousands of diverse cargo. Despite detailed under- standing of COPII subunits, the molecular mechanisms of coat assembly and membrane deformation are debated. Here we present a 4.9 Å cryo-tomography sub-tomogram aver aging structure of in vitro-reconstituted membrane-bound inner coat. We show that the outer coat (Sec13–Sec31) bridges inner coat subunits (Sar1–Sec23–Sec24), promoting their assembly into a tight lattice. We directly visualize the membrane-embedded Sar1 amphi- pathic helix, revealing that lattice formation induces parallel helix insertions, yielding tubular curvature. We propose that regulators like the procollagen receptor TANGO1 modulate this mechanism to determine vesicle shape and size.


    Item Type: Article
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Research Centres and Institutes: Structural Molecular Biology, Institute of (ISMB)
    Depositing User: Giulia Zanetti
    Date Deposited: 12 Oct 2018 08:05
    Last Modified: 02 Aug 2023 17:44


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