The cryo-EM structure of a pannexin 1 reveals unique motifs for ion selection and inhibition

  1. Kevin Michalski
  2. Johanna L Syrjanen
  3. Erik Henze
  4. Julia Kumpf
  5. Hiro Furukawa  Is a corresponding author
  6. Toshimitsu Kawate  Is a corresponding author
  1. Cornell University, United States
  2. Cold Spring Harbor Laboratory, United States

Abstract

Pannexins are large-pore forming channels responsible for ATP release under a variety of physiological and pathological conditions. Although predicted to share similar membrane topology with other large-pore forming proteins such as connexins, innexins, and LRRC8, pannexins have minimal sequence similarity to these protein families. Here, we present the cryo-EM structure of a frog pannexin 1 (Panx1) channel at 3.0 Å. We find that Panx1 protomers harbor four transmembrane helices similar in arrangement to other large-pore forming proteins but assemble as a heptameric channel with a unique constriction formed by Trp74 in the first extracellular loop. Mutating Trp74 or the nearby Arg75 disrupt ion selectivity whereas altering residues in the hydrophobic groove formed by the two extracellular loops abrogates channel inhibition by carbenoxolone. Our structural and functional study establishes the extracellular loops as important structural motifs for ion selectivity and channel inhibition in Panx1.

Data availability

Cryo EM data and the pannexin model has been deposited in PDB under the accession code 6VD7.

The following data sets were generated

Article and author information

Author details

  1. Kevin Michalski

    Molecular Medicine, Cornell University, Ithaca, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Johanna L Syrjanen

    WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Erik Henze

    Molecular Medicine, Cornell University, Ithaca, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Julia Kumpf

    Molecular Medicine, Cornell University, Ithaca, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3813-1255
  5. Hiro Furukawa

    WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, United States
    For correspondence
    furukawa@cshl.edu
    Competing interests
    The authors declare that no competing interests exist.
  6. Toshimitsu Kawate

    Department of Molecular Medicine, Cornell University, Ithaca, United States
    For correspondence
    toshi.kawate@cornell.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5005-2031

Funding

National Institutes of Health (GM114379)

  • Toshimitsu Kawate

National Institutes of Health (NS113632)

  • Hiro Furukawa

National Institutes of Health (GM008267)

  • Kevin Michalski
  • Erik Henze
  • Julia Kumpf

National Institutes of Health (GM008267)

  • Kevin Michalski

Robertson funds at Cold Spring Harbor Laboratory

  • Hiro Furukawa

Doug Fox Alzheimer's fund

  • Hiro Furukawa

Austin's purpose

  • Hiro Furukawa

Heartfelt Wing Alzheimer's fund

  • Hiro Furukawa

Charles H Revson Foundation (Senior Fellowship in Biomedical Science)

  • Johanna L Syrjanen

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 Institute of Neurological Disorders and Stroke, National Institutes of Health, United States

Publication history

  1. Received: December 21, 2019
  2. Accepted: February 11, 2020
  3. Accepted Manuscript published: February 12, 2020 (version 1)
  4. Version of Record published: March 31, 2020 (version 2)

Copyright

© 2020, Michalski 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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  1. Kevin Michalski
  2. Johanna L Syrjanen
  3. Erik Henze
  4. Julia Kumpf
  5. Hiro Furukawa
  6. Toshimitsu Kawate
(2020)
The cryo-EM structure of a pannexin 1 reveals unique motifs for ion selection and inhibition
eLife 9:e54670.
https://doi.org/10.7554/eLife.54670
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