1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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Unnatural amino acid photo-crosslinking of the IKs channel complex demonstrates a KCNE1:KCNQ1 stoichiometry of up to 4:4

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Cite this article as: eLife 2016;5:e11815 doi: 10.7554/eLife.11815

Abstract

Cardiac repolarization is determined in part by the slow delayed rectifier current (IKs), through the tetrameric voltage-gated ion channel, KCNQ1, and its β-subunit, KCNE1. The stoichiometry between α and β-subunits has been controversial with studies reporting either a strict 2 KCNE1:4 KCNQ1 or a variable ratio up to 4:4. We used IKs fusion proteins linking KCNE1 to one (EQ), two (EQQ) or four (EQQQQ) KCNQ1 subunits, to reproduce compulsory 4:4, 2:4 or 1:4 stoichiometries. Whole cell and single-channel recordings showed EQQ and EQQQQ to have increasingly hyperpolarized activation, reduced conductance, and shorter first latency of opening compared to EQ - all abolished by the addition of KCNE1. As well, using a UV-crosslinking unnatural amino acid in KCNE1, we found EQQQQ and EQQ crosslinking rates to be progressively slowed compared to KCNQ1, which demonstrates that no intrinsic mechanism limits the association of up to four β-subunits within the IKs complex.

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Author details

  1. Christopher I Murray

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    Competing interests
    The authors declare that no competing interests exist.
  2. Maartje Westhoff

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    Competing interests
    The authors declare that no competing interests exist.
  3. Jodene Eldstrom

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    Competing interests
    The authors declare that no competing interests exist.
  4. Emely Thompson

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    Competing interests
    The authors declare that no competing interests exist.
  5. Robert Emes

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    Competing interests
    The authors declare that no competing interests exist.
  6. David Fedida

    Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada
    For correspondence
    david.fedida@ubc.ca
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

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

Publication history

  1. Received: September 24, 2015
  2. Accepted: January 22, 2016
  3. Accepted Manuscript published: January 23, 2016 (version 1)
  4. Version of Record published: February 17, 2016 (version 2)

Copyright

© 2016, Murray 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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