1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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Anti-diabetic drug binding site in a mammalian KATP channel revealed by Cryo-EM

  1. Gregory M Martin
  2. Balamurugan Kandasamy
  3. Frank DiMaio
  4. Craig Yoshioka  Is a corresponding author
  5. Show-Ling Shyng  Is a corresponding author
  1. Oregon Health and Science University, United States
  2. University of Washington, United States
Research Article
  • Cited 57
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Cite this article as: eLife 2017;6:e31054 doi: 10.7554/eLife.31054

Abstract

Sulfonylureas are anti-diabetic medications that act by inhibiting pancreatic KATP channels composed of SUR1 and Kir6.2. The mechanism by which these drugs interact with and inhibit the channel has been extensively investigated, yet it remains unclear where the drug binding pocket resides. Here, we present a cryo-EM structure of a hamster SUR1/rat Kir6.2 channel bound to a high-affinity sulfonylurea drug glibenclamide and ATP at 3.63Å resolution, which reveals unprecedented details of the ATP and glibenclamide binding sites. Importantly, the structure shows for the first time that glibenclamide is lodged in the transmembrane bundle of the SUR1-ABC core connected to the first nucleotide binding domain near the inner leaflet of the lipid bilayer. Mutation of residues predicted to interact with glibenclamide in our model led to reduced sensitivity to glibenclamide. Our structure provides novel mechanistic insights of how sulfonylureas and ATP interact with the KATP channel complex to inhibit channel activity.

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Article and author information

Author details

  1. Gregory M Martin

    Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Balamurugan Kandasamy

    Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Frank DiMaio

    Department of Biochemistry, University of Washington, Seattle, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7524-8938

  4. Craig Yoshioka

    Department of Biomedical Engineering, Oregon Health and Science University, Portland, United States
    For correspondence
    yoshiokc@ohsu.edu
    Competing interests
    The authors declare that no competing interests exist.

  5. Show-Ling Shyng

    Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
    For correspondence
    shyngs@ohsu.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8230-8820

Funding

National Institute of Diabetes and Digestive and Kidney Diseases (R01DK066485)

  • Show-Ling Shyng

National Institute of Diabetes and Digestive and Kidney Diseases (F31DK105800)

  • Gregory M Martin

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: August 5, 2017
  2. Accepted: October 11, 2017
  3. Accepted Manuscript published: October 16, 2017 (version 1)
  4. Accepted Manuscript updated: October 18, 2017 (version 2)
  5. Version of Record published: October 24, 2017 (version 3)

Copyright

© 2017, Martin 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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    In many excitable cells, KATP channels respond to intracellular adenosine nucleotides: ATP inhibits while ADP activates. We present two structures of the human pancreatic KATP channel, containing the ABC transporter SUR1 and the inward-rectifier K+ channel Kir6.2, in the presence of Mg2+ and nucleotides. These structures, referred to as quatrefoil and propeller forms, were determined by single-particle cryo-EM at 3.9 Å and 5.6 Å, respectively. In both forms, ATP occupies the inhibitory site in Kir6.2. The nucleotide-binding domains of SUR1 are dimerized with Mg2+-ATP in the degenerate site and Mg2+-ADP in the consensus site. A lasso extension forms an interface between SUR1 and Kir6.2 adjacent to the ATP site in the propeller form and is disrupted in the quatrefoil form. These structures support the role of SUR1 as an ADP sensor and highlight the lasso extension as a key regulatory element in ADP’s ability to override ATP inhibition.

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