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Nat Commun. 2018 Mar 28;9(1):1255. doi: 10.1038/s41467-018-03603-3.

Opn5L1 is a retinal receptor that behaves as a reverse and self-regenerating photoreceptor.

Author information

1
Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558, Japan.
2
Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan.
3
Division of Analytical Laboratory, Kobe Pharmaceutical University, Kobe, 658-8558, Japan.
4
Department of Biology, Kyoto Prefectural University of Medicine, Kyoto, 603-8334, Japan.
5
Department of Chemistry, Graduate School of Science, Osaka University, Osaka, 560-0043, Japan.
6
Division of Chemical and Physical Analyses, Center for Technical Support, Institute of Technology and Science, Tokushima University, Tokushima, 770-8506, Japan.
7
Department of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Kobe, 658-8558, Japan.
8
Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan. shichida@rh.biophys.kyoto-u.ac.jp.
9
Research Organization for Science and Technology, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan. shichida@rh.biophys.kyoto-u.ac.jp.

Abstract

Most opsins are G protein-coupled receptors that utilize retinal both as a ligand and as a chromophore. Opsins' main established mechanism is light-triggered activation through retinal 11-cis-to-all-trans photoisomerization. Here we report a vertebrate non-visual opsin that functions as a Gi-coupled retinal receptor that is deactivated by light and can thermally self-regenerate. This opsin, Opn5L1, binds exclusively to all-trans-retinal. More interestingly, the light-induced deactivation through retinal trans-to-cis isomerization is followed by formation of a covalent adduct between retinal and a nearby cysteine, which breaks the retinal-conjugated double bond system, probably at the C11 position, resulting in thermal re-isomerization to all-trans-retinal. Thus, Opn5L1 acts as a reverse photoreceptor. We conclude that, like vertebrate rhodopsin, Opn5L1 is a unidirectional optical switch optimized from an ancestral bidirectional optical switch, such as invertebrate rhodopsin, to increase the S/N ratio of the signal transduction, although the direction of optimization is opposite to that of vertebrate rhodopsin.

PMID:
29593298
PMCID:
PMC5871776
DOI:
10.1038/s41467-018-03603-3
[Indexed for MEDLINE]
Free PMC Article

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