1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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Helical jackknives control the gates of the double-pore K+ uptake system KtrAB

  1. Marina Diskowski
  2. Ahmad Reza Mehdipour
  3. Dorith Wunnicke
  4. Deryck J Mills
  5. Vedrana Mikusevic
  6. Natalie Bärland
  7. Jan Hoffmann
  8. Nina Morgner
  9. Heinz-Jürgen Steinhoff
  10. Gerhard Hummer
  11. Janet Vonck  Is a corresponding author
  12. Inga Haenelt  Is a corresponding author
  1. Goethe-University, Germany
  2. Max Planck Institute of Biophysics, Germany
  3. University of Osnabrück, Germany
Research Article
  • Cited 8
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Cite this article as: eLife 2017;6:e24303 doi: 10.7554/eLife.24303

Abstract

Ion channel gating is essential for cellular homeostasis and is tightly controlled. In some eukaryotic and most bacterial ligand-gated K+ channels, RCK domains regulate ion fluxes. Until now, a single regulatory mechanism has been proposed for all RCK-regulated channels, involving signal transduction from the RCK domain to the gating area. Here we present an inactive ADP-bound structure of KtrAB from Vibrio alginolyticus, determined by cryo-electron microscopy, which, combined with EPR spectroscopy and molecular dynamics simulations, uncovers a novel regulatory mechanism for ligand-induced action at a distance. Exchange of activating ATP to inactivating ADP triggers short helical segments in the K+-translocating KtrB dimer to organize into two long helices that penetrate deeply into the regulatory RCK domains, thus connecting nucleotide binding sites and ion gates. As KtrAB and its homolog TrkAH have been implicated as bacterial pathogenicity factors, the discovery of this functionally relevant inactive conformation may advance structure-guided drug development.

Article and author information

Author details

  1. Marina Diskowski

    Institute of Biochemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  2. Ahmad Reza Mehdipour

    Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Dorith Wunnicke

    Institute of Biochemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Deryck J Mills

    Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  5. Vedrana Mikusevic

    Institute of Biochemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  6. Natalie Bärland

    Institute of Biochemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  7. Jan Hoffmann

    Institute of Physical and Theoretical Chemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  8. Nina Morgner

    Institute of Physical and Theoretical Chemistry, Goethe-University, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1872-490X
  9. Heinz-Jürgen Steinhoff

    Department of Physics, University of Osnabrück, Osnabrück, Germany
    Competing interests
    The authors declare that no competing interests exist.
  10. Gerhard Hummer

    Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
    Competing interests
    The authors declare that no competing interests exist.
  11. Janet Vonck

    Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
    For correspondence
    janet.vonck@biophys.mpg.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5659-8863
  12. Inga Haenelt

    Institute of Biochemistry, Goethe-University, Frankfurt, Germany
    For correspondence
    haenelt@biochem.uni-frankfurt.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1495-3163

Funding

Deutsche Forschungsgemeinschaft (HA 6322/3-1)

  • Inga Haenelt

Max Planck Society

  • Ahmad Reza Mehdipour
  • Deryck J Mills
  • Gerhard Hummer
  • Janet Vonck

Deutsche Forschungsgemeinschaft (HA 6322/2-1)

  • Inga Haenelt

Deutsche Forschungsgemeinschaft (SFB 807)

  • Nina Morgner
  • Gerhard Hummer
  • Inga Haenelt

Deutsche Forschungsgemeinschaft (CEF Macromolecular Complexes)

  • Ahmad Reza Mehdipour
  • Inga Haenelt

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

Reviewing Editor

  1. Kenton J Swartz, National Institutes of Health, United States

Publication history

  1. Received: December 15, 2016
  2. Accepted: May 14, 2017
  3. Accepted Manuscript published: May 15, 2017 (version 1)
  4. Accepted Manuscript updated: May 16, 2017 (version 2)
  5. Version of Record published: May 30, 2017 (version 3)

Copyright

© 2017, Diskowski 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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