Crystal structure of a natural light-gated anion channelrhodopsin

  1. Hai Li
  2. Chia-Ying Huang
  3. Elena G Govorunova
  4. Christopher T Schafer
  5. Oleg A Sineshchekov
  6. Meitian Wang
  7. Lei Zheng  Is a corresponding author
  8. John L Spudich  Is a corresponding author
  1. University of Texas Health Science Center at Houston, McGovern Medical School, United States
  2. Swiss Light Source, Paul Scherrer Institute, Switzerland

Abstract

The anion channelrhodopsin GtACR1 from the alga Guillardia theta is a potent neuron-inhibiting optogenetics tool. Presented here, its X-ray structure at 2.9 Å reveals a tunnel traversing the protein from its extracellular surface to a large cytoplasmic cavity. The tunnel is lined primarily by small polar and aliphatic residues essential for anion conductance. A disulfide-immobilized extracellular cap facilitates channel closing and the ion path is blocked mid-membrane by its photoactive retinylidene chromophore and further by a cytoplasmic side constriction. The structure also reveals a novel photoactive site configuration that maintains the retinylidene Schiff base protonated when the channel is open. These findings suggest a new channelrhodopsin mechanism, in which the Schiff base not only controls gating, but also serves as a direct mediator for anion flux.

Data availability

Diffraction data have been deposited in PDB under the accession code 6EDQ.

The following data sets were generated

Article and author information

Author details

  1. Hai Li

    Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3969-6709
  2. Chia-Ying Huang

    Macromolecular Crystallography, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
    Competing interests
    No competing interests declared.
  3. Elena G Govorunova

    Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    Competing interests
    Elena G Govorunova, and The University of Texas Health Science Center at Houston have filed patent applications that relate to ACRs (PCT application PCT/US2016/023095, entitled Compositions And Methods For Use Of Anion Channel Rhodopsins).
  4. Christopher T Schafer

    Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    Competing interests
    No competing interests declared.
  5. Oleg A Sineshchekov

    Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    Competing interests
    Oleg A Sineshchekov, and The University of Texas Health Science Center at Houston have filed patent applications that relate to ACRs (PCT application PCT/US2016/023095, entitled Compositions And Methods For Use Of Anion Channel Rhodopsins).
  6. Meitian Wang

    Macromolecular Crystallography, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
    Competing interests
    No competing interests declared.
  7. Lei Zheng

    Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    For correspondence
    Lei.Zheng@uth.tmc.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7789-5234
  8. John L Spudich

    Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, United States
    For correspondence
    John.L.Spudich@uth.tmc.edu
    Competing interests
    John L Spudich, and The University of Texas Health Science Center at Houston have filed patent applications that relate to ACRs (PCT application PCT/US2016/023095, entitled Compositions And Methods For Use Of Anion Channel Rhodopsins).
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4167-8590

Funding

National Institutes of Health (R01GM027750)

  • John L Spudich

National Institutes of Health (U01MH109146)

  • John L Spudich

Welch Foundation (AU-0009)

  • John L Spudich

American Heart Association (18TPA34230046)

  • Lei Zheng

Hermann Eye Fund

  • John L Spudich

Marie-Skłodowska-Curie (701647)

  • Chia-Ying Huang

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

Reviewing Editor

  1. Sriram Subramaniam, University of British Columbia, Canada

Publication history

  1. Received: September 5, 2018
  2. Accepted: January 4, 2019
  3. Accepted Manuscript published: January 7, 2019 (version 1)
  4. Version of Record published: January 17, 2019 (version 2)

Copyright

© 2019, Li 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. Hai Li
  2. Chia-Ying Huang
  3. Elena G Govorunova
  4. Christopher T Schafer
  5. Oleg A Sineshchekov
  6. Meitian Wang
  7. Lei Zheng
  8. John L Spudich
(2019)
Crystal structure of a natural light-gated anion channelrhodopsin
eLife 8:e41741.
https://doi.org/10.7554/eLife.41741

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