1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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The dimerization equilibrium of a ClC Cl-/H+ antiporter in lipid bilayers

Research Article
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Cite this article as: eLife 2016;5:e17438 doi: 10.7554/eLife.17438

Abstract

Interactions between membrane protein interfaces in lipid bilayers play an important role in membrane protein folding but quantification of the strength of these interactions has been challenging. Studying dimerization of ClC-type transporters offers a new approach to the problem, as individual subunits adopt a stable and functionally verifiable fold that constrains the system to two states - monomer or dimer. Here, we use single-molecule photobleaching analysis to measure the probability of ClC-ec1 subunit capture into liposomes during extrusion of large, multilamellar membranes. The capture statistics describe a monomer to dimer transition that is dependent on the subunit/lipid mole fraction density and follows an equilibrium dimerization isotherm. This allows for the measurement of the free energy of ClC-ec1 dimerization in lipid bilayers, revealing that it is one of the strongest membrane protein complexes measured so far, and introduces it as new type of dimerization model to investigate the physical forces that drive membrane protein association in membranes.

Article and author information

Author details

  1. Rahul Chadda

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Venkatramanan Krishnamani

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Kacey Mersch

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Jason Wong

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Marley Brimberry

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Ankita Chadda

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Ludmila Kolmakova-Partensky

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Larry J Friedman

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4946-8731
  9. Jeff Gelles

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7910-3421
  10. Janice L Robertson

    Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, United States
    For correspondence
    janice-robertson@uiowa.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5499-9943

Funding

National Institutes of Health (R00GM101016)

  • Venkatramanan Krishnamani
  • Kacey Mersch
  • Janice L Robertson

Roy J. Carver Charitable Trust (Early Investigator Award)

  • Rahul Chadda
  • Marley Brimberry
  • Ankita Chadda
  • Janice L Robertson

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

Reviewing Editor

  1. Olga Boudker, Weill Cornell Medical College, United States

Publication history

  1. Received: May 1, 2016
  2. Accepted: July 29, 2016
  3. Accepted Manuscript published: August 3, 2016 (version 1)
  4. Version of Record published: September 2, 2016 (version 2)

Copyright

© 2016, Chadda 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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