1. Biochemistry and Chemical Biology
  2. Cell Biology
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The packing density of a supramolecular membrane protein cluster is controlled by cytoplasmic interactions

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Cite this article as: eLife 2017;6:e20705 doi: 10.7554/eLife.20705

Abstract

Molecule clustering is an important mechanism underlying cellular self-organization. In the cell membrane, a variety of fundamentally different mechanisms drive membrane protein clustering into nanometre-sized assemblies. To date, it is unknown whether this clustering process can be dissected into steps differentially regulated by independent mechanisms. Using clustered syntaxin molecules as an example, we study the influence of a cytoplasmic protein domain on the clustering behaviour. Analysing protein mobility, cluster size and accessibility to myc-epitopes we show that forces acting on the transmembrane segment produce loose-clusters, while cytoplasmic protein interactions mediate a tightly packed state. We conclude that the data identify a hierarchy in membrane protein clustering likely being a paradigm for many cellular self-organization processes.

Article and author information

Author details

  1. Elisa Merklinger

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  2. Jan-Gero Schloetel

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Pascal Weber

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Helena Batoulis

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  5. Sarah Holz

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  6. Nora Karnowski

    Chemical Biology, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  7. Jérôme Finke

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    Competing interests
    The authors declare that no competing interests exist.
  8. Thorsten Lang

    Membrane Biochemistry, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
    For correspondence
    thorsten.lang@uni-bonn.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9128-0137

Funding

Deutsche Forschungsgemeinschaft (TRR83 to T.L.)

  • Thorsten Lang

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

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

Publication history

  1. Received: August 16, 2016
  2. Accepted: July 17, 2017
  3. Accepted Manuscript published: July 19, 2017 (version 1)
  4. Version of Record published: July 31, 2017 (version 2)

Copyright

© 2017, Merklinger 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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    SNARE proteins have been described as the effectors of fusion events in the secretory pathway more than two decades ago. The strong interactions between SNARE domains are clearly important in membrane fusion, but it is unclear whether they are involved in any other cellular processes. Here, we analyzed two classical SNARE proteins, syntaxin 1A and SNAP25. Although they are supposed to be engaged in tight complexes, we surprisingly find them largely segregated in the plasma membrane. Syntaxin 1A only occupies a small fraction of the plasma membrane area. Yet, we find it is able to redistribute the far more abundant SNAP25 on the mesoscale by gathering crowds of SNAP25 molecules onto syntaxin clusters in a SNARE-domain-dependent manner. Our data suggest that SNARE domain interactions are not only involved in driving membrane fusion on the nanoscale, but also play an important role in controlling the general organization of proteins on the mesoscale. Further, we propose these mechanisms preserve active syntaxin 1A–SNAP25 complexes at the plasma membrane.