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Nat Commun. 2018 Sep 26;9(1):3949. doi: 10.1038/s41467-018-06421-9.

Crystal structure of the red light-activated channelrhodopsin Chrimson.

Author information

1
Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo, 113-0034, Japan.
2
Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany.
3
Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg (ZMNH), 20251, Hamburg, Germany.
4
RIKEN SPring-8 Center, Sayo, 679-5198, Japan.
5
Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo, 113-0034, Japan. t-2438@bs.s.u-tokyo.ac.jp.
6
Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan. t-2438@bs.s.u-tokyo.ac.jp.
7
Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany. hegemann@rz.hu-berlin.de.
8
Department of Biological Sciences Graduate School of Science, The University of Tokyo, Tokyo, 113-0034, Japan. nureki@bs.s.u-tokyo.ac.jp.

Abstract

Channelrhodopsins are light-activated ion channels that mediate cation permeation across cell membranes upon light absorption. Red-light-activated channelrhodopsins are of particular interest, because red light penetrates deeper into biological tissues and also enables dual-color experiments in combination with blue-light-activated optogenetic tools. Here we report the crystal structure of the most red-shifted channelrhodopsin from the algae Chlamydomonas noctigama, Chrimson, at 2.6 Å resolution. Chrimson resembles prokaryotic proton pumps in the retinal binding pocket, while sharing similarity with other channelrhodopsins in the ion-conducting pore. Concomitant mutation analysis identified the structural features that are responsible for Chrimson's red light sensitivity; namely, the protonation of the counterion for the retinal Schiff base, and the polar residue distribution and rigidity of the retinal binding pocket. Based on these mechanistic insights, we engineered ChrimsonSA, a mutant with a maximum activation wavelength red-shifted beyond 605 nm and accelerated closing kinetics.

PMID:
30258177
PMCID:
PMC6158191
DOI:
10.1038/s41467-018-06421-9
[Indexed for MEDLINE]
Free PMC Article

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