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An All-Trans-Retinal-Binding Opsin Peropsin as a Potential Dark-Active and Light-Inactivated G Protein-Coupled Receptor

An All-Trans-Retinal-Binding Opsin Peropsin as a Potential Dark-Active and Light-Inactivated G Protein-Coupled Receptor

Takashi Nagata, Mitsumasa Koyanagi, Robert Lucas, Akihisa Terakita

Sci Rep. 2018 Feb 23;8(1):3535.

PMID: 29476064

Abstract:

Peropsin or retinal pigment epithelium-derived rhodopsin homolog, found in many animals, belongs to the opsin family. Most opsins bind to 11-cis-retinal as a chromophore and act as light-activated G protein-coupled receptors. Some peropsins, however, bind all-trans-retinal and isomerise it into 11-cis form by light, and peropsin has been suggested to supply other visual opsins with 11-cis-retinal. Additionally, peropsin has some amino acid sequence motifs that are highly conserved among G protein-coupled opsins. Here, using chimeric mutant peropsins, we found that peropsin potentially generates an "active form" that drives G-protein signalling in the dark by binding to all-trans-retinal and that the active form photo-converts to an inactive form containing 11-cis-retinal. Comparative spectroscopic analysis demonstrated that spider peropsin exhibited catalytic efficiency for retinal photoisomerisation that was much lower than a retinal photoisomerase, squid retinochrome. The chimeric peropsins, constructed by replacing the third intracellular loop region with that of Gs- or Gi-coupled opsin, were active and drove Gs- or Gi-mediated signalling in the dark, respectively, and were inactivated upon illumination in mammalian cultured cells. These results suggest that peropsin acts as a dark-active, light-inactivated G protein-coupled receptor and is useful as a novel optogenetic tool.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP116314	all trans-Retinal		116-31-4	Price

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