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Science. 2017 Nov 24;358(6366). pii: eaan8862. doi: 10.1126/science.aan8862.

Structural insights into ion conduction by channelrhodopsin 2.

Author information

1
Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany.
2
Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.
3
Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
4
Institute of Crystallography, University of Aachen, Aachen, Germany.
5
ELI Beamlines, Institute of Physics, Czech Academy of Sciences, 18221 Prague, Czech Republic.
6
Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
7
European Synchrotron Radiation Facility, 38027 Grenoble, France.
8
Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
9
Max Planck Institute of Biophysics, Frankfurt am Main, Germany. ernst.bamberg@biophys.mpg.de valentin.gordeliy@ibs.fr.
10
Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany. ernst.bamberg@biophys.mpg.de valentin.gordeliy@ibs.fr.

Abstract

The light-gated ion channel channelrhodopsin 2 (ChR2) from Chlamydomonas reinhardtii is a major optogenetic tool. Photon absorption starts a well-characterized photocycle, but the structural basis for the regulation of channel opening remains unclear. We present high-resolution structures of ChR2 and the C128T mutant, which has a markedly increased open-state lifetime. The structure reveals two cavities on the intracellular side and two cavities on the extracellular side. They are connected by extended hydrogen-bonding networks involving water molecules and side-chain residues. Central is the retinal Schiff base that controls and synchronizes three gates that separate the cavities. Separate from this network is the DC gate that comprises a water-mediated bond between C128 and D156 and interacts directly with the retinal Schiff base. Comparison with the C128T structure reveals a direct connection of the DC gate to the central gate and suggests how the gating mechanism is affected by subtle tuning of the Schiff base's interactions.

PMID:
29170206
DOI:
10.1126/science.aan8862
[Indexed for MEDLINE]

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