Specific residues in the cytoplasmic domain modulate photocurrent kinetics of channelrhodopsin from Klebsormidium nitens

Specific residues in the cytoplasmic domain modulate photocurrent kinetics of channelrhodopsin from Klebsormidium nitens

Channelrhodopsins (ChRs) are light-gated ion channels extensively applied as optogenetics tools for manipulating neuronal activity. All currently known ChRs comprise a large cytoplasmic domain, whose function is elusive. Here, we report the cation channel properties of KnChR, one of the photorecepto...

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Published in:Communications biology Vol. 4; no. 1; p. 235
Main Authors: Tashiro, Rintaro, Sushmita, Kumari, Hososhima, Shoko, Sharma, Sunita, Kateriya, Suneel, Kandori, Hideki, Tsunoda, Satoshi P.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 23-02-2021
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Subjects:
14/1
14/19
14/35
631/1647/1453/1970
631/1647/1453/1971
631/1647/2253
9/74
Algae
Arginine
Biology
Biomedical and Life Sciences
C-Terminus
Color vision
Electrostatic properties
Genetics
Information processing
Ion channels
Kinetics
Klebsormidium
Life Sciences
Optics
Peptidoglycans
Photoreceptors
Rhodopsin
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Summary:Channelrhodopsins (ChRs) are light-gated ion channels extensively applied as optogenetics tools for manipulating neuronal activity. All currently known ChRs comprise a large cytoplasmic domain, whose function is elusive. Here, we report the cation channel properties of KnChR, one of the photoreceptors from a filamentous terrestrial alga Klebsormidium nitens , and demonstrate that the cytoplasmic domain of KnChR modulates the ion channel properties. KnChR is constituted of a 7-transmembrane domain forming a channel pore, followed by a C-terminus moiety encoding a peptidoglycan binding domain (FimV). Notably, the channel closure rate was affected by the C-terminus moiety. Truncation of the moiety to various lengths prolonged the channel open lifetime by more than 10-fold. Two Arginine residues (R287 and R291) are crucial for altering the photocurrent kinetics. We propose that electrostatic interaction between the rhodopsin domain and the C-terminus domain accelerates the channel kinetics. Additionally, maximal sensitivity was exhibited at 430 and 460 nm, the former making KnChR one of the most blue-shifted ChRs characterized thus far, serving as a novel prototype for studying the molecular mechanism of color tuning of the ChRs. Furthermore, KnChR would expand the optogenetics tool kit, especially for dual light applications when short-wavelength excitation is required. Tashiro et al. describe a new channelrhodopsin variant from a terrestrial algal species and the role of the C-terminal domain in regulatory function. This far-blue-shifted channelrhodopsin may contribute to optogenetic tool research in the future.
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ISSN:2399-3642
2399-3642
DOI:10.1038/s42003-021-01755-5