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Structure of the Sec13/31 COPII coat cage

Nature volume 439, pages 234–238 (2006)Cite this article

A Corrigendum to this article was published on 17 August 2006

Abstract

Endomembranes of eukaryotic cells are dynamic structures that are in continuous communication through the activity of specialized cellular machineries1, such as the coat protein complex II (COPII), which mediates cargo export from the endoplasmic reticulum (ER)2,3. COPII consists of the Sar1 GTPase, Sec23 and Sec24 (Sec23/24), where Sec23 is a Sar1-specific GTPase-activating protein and Sec24 functions in cargo selection, and Sec13 and Sec31 (Sec13/31), which has a structural role3. Whereas recent results have shown that Sec23/24 and Sec13/31 can self-assemble to form COPII cage-like particles4, we now show that Sec13/31 can self-assemble to form minimal cages in the absence of Sec23/24. We present a three-dimensional reconstruction of these Sec13/31 cages at 30 Å resolution using cryo-electron microscopy and single particle analysis. These results reveal a novel cuboctahedron geometry with the potential to form a flexible lattice and to generate a diverse range of containers. Our data are consistent with a model for COPII coat complex assembly in which Sec23/24 has a non-structural role as a multivalent ligand localizing the self-assembly of Sec13/31 to form a cage lattice driving ER cargo export.

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Figure 1: Initial analyses of the self-assembled Sec13/31 cages.
Figure 2: Comparison of the refined Sec13/31 cage structure to the raw data.
Figure 3: 30 Å resolution map of the Sec13/31 cage.
Figure 4: Orientation of the Sec13/31 heterotetramer in the self-assembled cuboctahedral cage.

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Acknowledgements

These studies are supported by NIH grants to W.E.B., C.S.P. and B.C. S.M.S. is a recipient of an NIH Postdoctoral Fellowship. C.G. is a recipient of a Cystic Fibrosis Foundation Postdoctoral Research Fellowship. We thank G. Cantin and J. Venable for LC-MS/MS analysis, and J. T. Weissman, K. Straley and S. J. Lloyd for setting up or helping with recombinant expression of the human Sec13/31 complex in baculovirus-infected insect cells. This is TSRI manuscript number 17546-CB.

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Author notes

  1. Scott M. Stagg and Cemal Gürkan: *These authors contributed equally to this work

Authors and Affiliations

  1. National Resource for Automated Molecular Microscopy, 10550 North Torrey Pines Road, California, 92037, La Jolla, USA

    Scott M. Stagg, Clinton S. Potter & Bridget Carragher

  2. Departments of Cell, 10550 North Torrey Pines Road, California, 92037, La Jolla, USA

    Scott M. Stagg, Cemal Gürkan, Douglas M. Fowler, Paul LaPointe, Clinton S. Potter, Bridget Carragher & William E. Balch

  3. Departments of Molecular Biology, 10550 North Torrey Pines Road, California, 92037, La Jolla, USA

    William E. Balch

  4. Departments of Chemistry, 10550 North Torrey Pines Road, California, 92037, La Jolla, USA

    Douglas M. Fowler & Ted R. Foss

  5. The Institute for Childhood and Neglected Disease, The Scripps Research Institute, 10550 North Torrey Pines Road, California, 92037, La Jolla, USA

    William E. Balch

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Correspondence to Bridget Carragher or William E. Balch.

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Supplementary information

Supplementary Notes

This file contains Supplementary Methods and Supplementary Figure Legends. (DOC 44 kb)

Supplementary Figure 1

Further initial analyses of the self-assembled Sec13/31 cages. (PDF 537 kb)

Supplementary Figure 2

Single particle analysis of the Sec13/31 cages in vitreous ice. (PDF 1587 kb)

Supplementary Figure 3

Further potential geometries consistent with a Sec13/31 lattice. (PDF 467 kb)

Supplementary Video

The reconstructed cage structure has a diameter of 600 A ° along its longest diagonal, the length of an edge is 300 Å, and the width of an edge is 40 Å. (MOV 3354 kb)

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Stagg, S., Gürkan, C., Fowler, D. et al. Structure of the Sec13/31 COPII coat cage. Nature 439, 234–238 (2006). https://doi.org/10.1038/nature04339

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