1. Biochemistry and Chemical Biology
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A distinct tethering step is vital for vacuole membrane fusion

  1. Michael Zick
  2. William T Wickner  Is a corresponding author
  1. Geisel School of Medicine at Dartmouth, United States
Research Article
  • Cited 38
  • Views 2,012
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Cite this article as: eLife 2014;3:e03251 doi: 10.7554/eLife.03251

Abstract

Past experiments with reconstituted proteoliposomes, employing assays that infer membrane fusion from fluorescent lipid dequenching, have suggested that vacuolar SNAREs alone suffice to catalyze membrane fusion in vitro. While we could replicate these results, we detected very little fusion with the more rigorous assay of lumenal compartment mixing. Exploring the discrepancies between lipid-dequenching and content-mixing assays, we surprisingly found that the disposition of the fluorescent lipids with respect to SNAREs had a striking effect. Without other proteins, the association of SNAREs in trans causes lipid dequenching that cannot be ascribed to fusion or hemifusion. Tethering of the SNARE-bearing proteoliposomes was required for efficient lumenal compartment mixing. While the physiological HOPS tethering complex caused a few-fold increase of trans-SNARE association, the rate of content mixing increased more than 100-fold. Thus tethering has a role in promoting membrane fusion that extends beyond simply increasing the amount of total trans-SNARE complex.

Article and author information

Author details

  1. Michael Zick

    Geisel School of Medicine at Dartmouth, Hanover, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. William T Wickner

    Geisel School of Medicine at Dartmouth, Hanover, United States
    For correspondence
    William.T.Wickner@dartmouth.edu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Axel T Brunger, Stanford University, United States

Publication history

  1. Received: May 4, 2014
  2. Accepted: September 24, 2014
  3. Accepted Manuscript published: September 25, 2014 (version 1)
  4. Version of Record published: October 17, 2014 (version 2)

Copyright

© 2014, Zick & Wickner

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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