1. Structural Biology and Molecular Biophysics
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Cryo-EM analysis of PIP2 regulation in mammalian GIRK channels

  1. Yiming Niu
  2. Xiao Tao
  3. Kouki K Touhara
  4. Roderick MacKinnon  Is a corresponding author
  1. Howard Hughes Medical Institute, The Rockefeller University, United States
Research Article
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Cite this article as: eLife 2020;9:e60552 doi: 10.7554/eLife.60552

Abstract

G protein-gated inward rectifier potassium (GIRK) channels are regulated by G proteins and PIP2. Here using cryo-EM single particle analysis we describe the equilibrium ensemble of structures of neuronal GIRK2 as a function of the C8-PIP2 concentration. We find that PIP2 shifts the equilibrium between two distinguishable structures of neuronal GIRK (GIRK2), extended and docked, towards the docked form. In the docked form the cytoplasmic domain, to which Gβγ binds, becomes accessible to the cytoplasmic membrane surface where Gβγ resides. Furthermore, PIP2 binding reshapes the Gβγ binding surface on the cytoplasmic domain, preparing it to receive Gβγ. We find that cardiac GIRK (GIRK1/4) can also exist in both extended and docked conformations. These findings lead us to conclude that PIP2 influences GIRK channels in a structurally similar manner to Kir2.2 channels. In Kir2.2 channels, the PIP2-induced conformational changes open the pore. In GIRK channels, they prepare the channel for activation by Gβγ.

Data availability

The B-factor sharpened 3D cryo-EM density map and atomic coordinates of GIRK2 in the extended conformation (GIRK2Extended) and GIRK2 in the docked conformation with PIP2 (GIRK2Docked) have been deposited in the Worldwide Protein Data Bank (wwPDB) under accession number EMD-22199 and 6XIS, EMD-22200 and 6XIT, respectively. The B-factor sharpened 3D cryo-EM density map of GIRK1/4 in the extended conformation (GIRK1/4Extended) and docked conformation with PIP2 (GIRK1/4Docked) have been deposited in the Worldwide Protein Data Bank (wwPDB) under accession number EMD-22201 and EMD-22202, respectively.

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Author details

  1. Yiming Niu

    Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5683-1781

  2. Xiao Tao

    Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9381-7903

  3. Kouki K Touhara

    Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3167-9784

  4. Roderick MacKinnon

    Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
    For correspondence
    mackinn@mail.rockefeller.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7605-4679

Funding

National Institutes of Health (GM43949)

  • Roderick MacKinnon

Howard Hughes Medical Institute

  • Roderick MacKinnon

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

Reviewing Editor

  1. Merritt Maduke, Stanford University School of Medicine, United States

Publication history

  1. Received: June 29, 2020
  2. Accepted: August 25, 2020
  3. Accepted Manuscript published: August 26, 2020 (version 1)
  4. Version of Record published: September 10, 2020 (version 2)

Copyright

© 2020, Niu 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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