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v-SNARE transmembrane domains function as catalysts for vesicle fusion

  1. Madhurima Dhara
  2. Antonio Yarzagaray
  3. Mazen Makke
  4. Barbara Schindeldecker
  5. Yvonne Schwarz
  6. Ahmed Shaaban
  7. Satyan Sharma
  8. Rainer A Böckmann
  9. Manfred Lindau
  10. Ralf Mohrmann
  11. Dieter Bruns  Is a corresponding author
  1. Saarland University, Germany
  2. Max-Planck-Institute for Biophysical Chemistry, Germany
  3. Friedrich-Alexander University, Germany
Research Article
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Cite this article as: eLife 2016;5:e17571 doi: 10.7554/eLife.17571

Abstract

Vesicle fusion is mediated by assembly of SNARE proteins between opposing membranes, but it is unknown whether transmembrane domains (TMDs) of SNARE proteins serve mechanistic functions that go beyond passive anchoring of the force-generating SNAREpin to the fusing membranes. Here, we show that conformational flexibility of synaptobrevin-2 TMD is essential for efficient Ca2+-triggered exocytosis and actively promotes membrane fusion as well as fusion pore expansion. Specifically, introduction of helix-stabilizing leucine residues within the TMD region spanning the vesicle's outer leaflet strongly impairs exocytosis and decelerates fusion pore dilation. In contrast, increasing the number of helix-destabilizing, ß-branched valine or isoleucine residues within the TMD restores normal secretion but accelerates fusion pore expansion beyond the rate found for the wildtype protein. These observations provide evidence that the synaptobrevin-2 TMD catalyzes the fusion process by its structural flexibility, actively setting the pace of fusion pore expansion.

Article and author information

Author details

  1. Madhurima Dhara

    Institute for Physiology, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  2. Antonio Yarzagaray

    Institute for Physiology, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Mazen Makke

    Institute for Physiology, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Barbara Schindeldecker

    Institute for Physiology, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  5. Yvonne Schwarz

    Institute for Physiology, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  6. Ahmed Shaaban

    Zentrum für Human- und Molekularbiologie, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  7. Satyan Sharma

    Group Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
    Competing interests
    The authors declare that no competing interests exist.
  8. Rainer A Böckmann

    Computational Biology, Friedrich-Alexander University, Erlangen, Germany
    Competing interests
    The authors declare that no competing interests exist.
  9. Manfred Lindau

    Group Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
    Competing interests
    The authors declare that no competing interests exist.
  10. Ralf Mohrmann

    Zentrum für Human- und Molekularbiologie, Saarland University, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  11. Dieter Bruns

    Institute for Physiology, Saarland University, Homburg, Germany
    For correspondence
    dieter.bruns@uks.eu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Reinhard Jahn, Max Planck Institute for Biophysical Chemistry, Germany

Publication history

  1. Received: May 5, 2016
  2. Accepted: June 24, 2016
  3. Accepted Manuscript published: June 25, 2016 (version 1)
  4. Version of Record published: August 3, 2016 (version 2)

Copyright

© 2016, Dhara et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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