Structural insights into light-gating of potassium-selective channelrhodopsin
Structural information on channelrhodopsins' mechanism of light-gated ion conductance is scarce, limiting its engineering as optogenetic tools. Here, we use single-particle cryo-electron microscopy of peptidisc-incorporated protein samples to determine the structures of the slow-cycling mutant C110A of kalium channelrhodopsin 1 from Hyphochytrium catenoides (HcKCR1) in the dark and upon laser flash excitation. Upon photoisomerization of the retinal chromophore, the retinylidene Schiff base NH-bond reorients from the extracellular to the cytoplasmic side. This switch triggers a series of side chain reorientations and merges intramolecular cavities into a transmembrane K<sup>+</sup> conduction pathway. Molecular dynamics simulations confirm K<sup>+</sup> flux through the illuminated state but not through the resting state. The overall displacement between the closed and the open structure is small, involving mainly side chain rearrangements. Asp105 and Asp116 play a key role in K<sup>+</sup> conductance. Structure-guided mutagenesis and patch-clamp analysis reveal the roles of the pathway-forming residues in channel gating and selectivity.
Authors
- Probal Nag (ORCID: https://orcid.org/0000-0001-7414-1824)
- Oliver P. Ernst (ORCID: https://orcid.org/0000-0002-8863-9444)
- Oleg A. Sineshchekov (ORCID: https://orcid.org/0000-0002-6358-7764)
- Elena G. Govorunova (ORCID: https://orcid.org/0000-0003-0522-9683)
- Igor Schapiro (ORCID: https://orcid.org/0000-0001-8536-6869)
- Takefumi Morizumi (ORCID: https://orcid.org/0000-0002-2785-209X)
- Ana‐Nicoleta Bondar (ORCID: https://orcid.org/0000-0003-2636-9773)
- Songhwan Hwang (ORCID: https://orcid.org/0000-0003-4323-1450)
- Kyumhyuk Kim (ORCID: https://orcid.org/0000-0002-1870-7296)
- John L. Spudich (ORCID: https://orcid.org/0000-0003-4167-8590)
- Leonid S. Brown (ORCID: https://orcid.org/0000-0002-5614-8317)
- Han Sun (ORCID: https://orcid.org/0000-0002-1655-0838)
- Hai Li (ORCID: https://orcid.org/0000-0002-3969-6709)
- Yumei Wang (ORCID: https://orcid.org/0000-0002-0551-3468)
- Tal Dogon
Institutions
- University of Bucharest (RO)
- Forschungszentrum Jülich (DE)
- University of Toronto (CA)
- Hebrew University of Jerusalem (IL)
- TU Dortmund University (DE)
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (DE)
- The University of Texas Health Science Center (US)
- Technische Universität Berlin (DE)
- University of Guelph (CA)
- The University of Texas Health Science Center at Houston (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-02-03
- DOI
- https://doi.org/10.1038/s41467-025-56491-9
- Citations
- 7
- Primary Topic
- Photoreceptor and optogenetics research
- Type
- article
- Field-Weighted Citation Impact
- 6.36
Funders
- University of Texas Health Science Center at Houston
- Deutsche Forschungsgemeinschaft
- Forschungszentrum Jülich
- Israel Science Foundation
- National Institutes of Health
- Canadian Institutes of Health Research
- Natural Sciences and Engineering Research Council of Canada