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Title: Red-Tuning of the Channelrhodopsin Spectrum Using Long Conjugated Retinal Analogues
Authors: Shen, Yi-Chung
Sasaki, Toshikazu
Matsuyama, Take
Yamashita, Takahiro  kyouindb  KAKEN_id
Shichida, Yoshinori
Okitsu, Takashi
Yamano, Yumiko
Wada, Akimori
Ishizuka, Toru
Yawo, Hiromu
Imamoto, Yasushi  kyouindb  KAKEN_id  orcid (unconfirmed)
Author's alias: 山下, 高廣
今元, 泰
Issue Date: 25-Sep-2018
Publisher: American Chemical Society (ACS)
Journal title: Biochemistry
Volume: 57
Issue: 38
Start page: 5544
End page: 5556
Abstract: As optogenetic studies become more popular, the demand for red-shifted channelrhodopsin is increasing, because blue-green light is highly scattered or absorbed by animal tissues. In this study, we developed a red-shifted channelrhodopsin by elongating the conjugated double-bond system of the native chromophore, all-trans-retinal (ATR1). Analogues of ATR1 and ATR2 (3, 4-didehydro-retinal) in which an extra C═C bond is inserted at different positions (C6–C7, C10–C11, and C14–C15) were synthesized and introduced into a widely used channelrhodopsin variant, C1C2 (a chimeric protein of channelrhodopsin-1 and channelrhodopsin-2 from Chlamydomonas reinhardtii). C1C2 bearing these retinal analogues as chromophores showed broadened absorption spectra toward the long-wavelength side and photocycle intermediates similar to the conducting state of channelrhodopsin. However, the position of methyl groups on the retinal polyene chain influenced the yield of the pigment, absorption maximum, and photocycle pattern to a variable degree. The lack of a methyl group at position C9 of the analogues considerably decreased the yield of the pigment, whereas a methyl group at position C15 exhibited a large red-shift in the absorption spectra of the C1C2 analogue. Expansion of the chromophore binding pocket by mutation of aromatic residue Phe265 to Ala improved the yield of the pigment bearing elongated ATR1 analogues without a great alteration of the photocycle kinetics of C1C2. Our results show that elongation of the conjugated double-bond system of retinal is a promising strategy for improving the ability of channelrhodopsin to absorb long-wavelength light passing through the biological optical window.
Rights: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Biochemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
The full-text file will be made open to the public on 28 August 2019 in accordance with publisher's 'Terms and Conditions for Self-Archiving'.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
DOI(Published Version): 10.1021/acs.biochem.8b00583
PubMed ID: 30153419
Appears in Collections:Journal Articles

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