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Supramolecular SNARE assembly precedes hemifusion in SNARE-mediated membrane fusion

Nature Structural & Molecular Biology volume 15, pages 700–706 (2008)Cite this article

Abstract

Formation of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex facilitates intracellular membrane fusion. A single SNARE complex is thought to be insufficient; multiple copies of SNARE complexes must work cooperatively. However, the mechanism by which such a higher-order SNARE protein structure is assembled is unknown. EPR and fluorescence analyses show that at least three copies of target-membrane SNARE proteins self-assemble through the interaction between the transmembrane domains (TMDs), and this multimeric structure serves as scaffolding for trans-SNARE assembly. SNARE core formation in solution induces oligomerization of the TMDs of vesicle-associated SNAREs in the apposing membrane, transiently forming a supramolecular protein structure spanning two membranes. This higher-order protein intermediate evolves, by involving lipid molecules, to the hemifusion state. Hemifusion is subsequently followed by distal leaflet mixing and formation of the cis-SNARE complex.

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Figure 1: Determination of stoichiometry of the Sso1pHT TMD oligomer using EPR.
Figure 2: Fluorescence detection of SNARE assembly at different locations.
Figure 3: Fluorescence lipid-mixing assay.
Figure 4: Kinetic comparison of various fluorescence assays.
Figure 5: A mechanistic model for SNARE assembly and membrane fusion.

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Acknowledgements

Support for this work was provided by the US National Institutes of Health.

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Author notes

  1. Xiaobing Lu and Yinghui Zhang: These authors contributed equally to this work.

Authors and Affiliations

  1. Department of Biochemistry, Biophysics and Molecular Biology, Molecular Biology Building, Iowa State University, Ames, 50011, Iowa, USA

    Xiaobing Lu, Yinghui Zhang & Yeon-Kyun Shin

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  1. Xiaobing Lu
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  2. Yinghui Zhang
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Contributions

X.L. performed the fluorescence assay; Y.Z. performed the EPR analysis. Y.-K.S. designed the experiment and wrote the paper.

Corresponding author

Correspondence to Yeon-Kyun Shin.

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Lu, X., Zhang, Y. & Shin, YK. Supramolecular SNARE assembly precedes hemifusion in SNARE-mediated membrane fusion. Nat Struct Mol Biol 15, 700–706 (2008). https://doi.org/10.1038/nsmb.1433

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