1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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Structure and transport mechanism of the sodium/proton antiporter MjNhaP1

  1. Cristina Paulino
  2. David Wöhlert
  3. Ekaterina Kapotova
  4. Özkan Yildiz  Is a corresponding author
  5. Werner Kühlbrandt
  1. Max Planck Institute of Biophysics, Germany
Research Article
  • Cited 40
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Cite this article as: eLife 2014;3:e03583 doi: 10.7554/eLife.03583

Abstract

Sodium/proton antiporters are essential for sodium and pH homeostasis and play a major role in human health and disease. We determined the structures of the archaeal sodium/proton antiporter MjNhaP1 in two complementary states. The inward-open state was obtained by x-ray crystallography in the presence of sodium at pH8, where the transporter is highly active. The outward-open state was obtained by electron crystallography without sodium at pH4, where MjNhaP1 is inactive. Comparison of both structures reveals a 7° tilt of the 6 helix bundle. 22Na+ uptake measurements indicate non-cooperative transport with an activity maximum at pH7.5. We conclude that binding of a Na+ ion from the outside induces helix movements that close the extracellular cavity, open the cytoplasmic funnel, and result in a ~5 Å vertical relocation of the ion binding site to release the substrate ion into the cytoplasm.

Article and author information

Author details

  1. Cristina Paulino

    Max Planck Institute of Biophysics, Frankfurt am Main, Germany
    Competing interests
    No competing interests declared.
  2. David Wöhlert

    Max Planck Institute of Biophysics, Frankfurt am Main, Germany
    Competing interests
    No competing interests declared.
  3. Ekaterina Kapotova

    Max Planck Institute of Biophysics, Frankfurt am Main, Germany
    Competing interests
    No competing interests declared.
  4. Özkan Yildiz

    Max Planck Institute of Biophysics, Frankfurt am Main, Germany
    For correspondence
    Oezkan.Yildiz@biophys.mpg.de
    Competing interests
    No competing interests declared.
  5. Werner Kühlbrandt

    Max Planck Institute of Biophysics, Frankfurt am Main, Germany
    Competing interests
    Werner Kühlbrandt, Reviewing editor, eLife.

Reviewing Editor

  1. Richard Aldrich, The University of Texas at Austin, United States

Publication history

  1. Received: June 6, 2014
  2. Accepted: November 14, 2014
  3. Accepted Manuscript published: November 26, 2014 (version 1)
  4. Accepted Manuscript updated: November 28, 2014 (version 2)
  5. Version of Record published: December 16, 2014 (version 3)

Copyright

© 2014, Paulino 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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