Functional characterization of four opsins and two G alpha subtypes co-expressed in the molluscan rhabdomeric photoreceptor

BMC Biology · 8 authors, 6 centres

AI SUMMARY

FIDELITY 100%

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

TRACE TO SOURCE

“

TL;DR

This study characterizes four distinct visual opsins co-expressed in the photoreceptor of the terrestrial slug Limax. It finds the opsins have different spectral sensitivities and can activate different G protein subtypes, suggesting a complex signaling network that may fine-tune vision.

Full summary

838 CHARS

Researchers characterized the functional properties of four visual opsins (Gq-rhodopsin, xenopsin, Opn5A, and Opn5B) co-expressed in the rhabdomeric photoreceptor of the terrestrial slug Limax. Using biochemical and spectroscopic methods, they determined the opsins' peak spectral sensitivities: Gq-rhodopsin at ~456 nm, xenopsin at ~475 nm, Opn5A at ~500 nm, and Opn5B at ~470 nm, with Opn5A and Opn5B also showing UV sensitivity. In vitro assays demonstrated that while only Gq-rhodopsin activated the Gq alpha subtype, all four opsins activated the Go alpha subtype, indicating complex G protein signaling pathways. The combination of opsins with different spectral sensitivities and G protein selectivities is proposed to underlie physiological properties like the shift in spectral sensitivity between dark- and light-adapted states.

STUDY TYPE

other

SPECIALTY

ophthalmology

SUMMARISED BY

AI pipeline

FIDELITY CHECK

100% · A

ORIGINAL PAPER

PMC10729476

Functional characterization of four opsins and two G alpha subtypes co-expressed in the molluscan rhabdomeric photoreceptor

BMC Biology

READ THE FULL PAPER

ABSTRACT

Background Rhabdomeric photoreceptors of eyes in the terrestrial slug Limax are the typical invertebrate-type but unique in that three visual opsins (Gq-coupled rhodopsin, xenopsin, Opn5A) and one retinochrome, all belonging to different groups, are co-expressed. However, molecular properties including spectral sensitivity and G protein selectivity of any of them are not determined, which prevents us from understanding an advantage of multiplicity of opsin properties in a single rhabdomeric photoreceptor. To gain insight into the functional role of the co-expression of multiple opsin species in a photoreceptor, we investigated the molecular properties of the visual opsins in the present study. Results First, we found that the fourth member of visual opsins, Opn5B, is also co-expressed in the rhabdomere of the photoreceptor together with previously identified three opsins. The photoreceptors were also demonstrated to express Gq and Go alpha subunits. We then determined the spectral sensitivity of the four visual opsins using biochemical and spectroscopic methods. Gq-coupled rhodopsin and xenopsin exhibit maximum sensitivity at ~ 456 and 475 nm, respectively, and Opn5A and Opn5B exhibit maximum sensitivity at ~ 500 and 470 nm, respectively, with significant UV sensitivity. Notably, in vitro experiments revealed that Go alpha was activated by all four visual opsins, in contrast to the specific activation of Gq alpha by Gq-coupled rhodopsin, suggesting that the eye photoreceptor of Limax uses complex G protein signaling pathways. Conclusions The eye photoreceptor in Limax expresses as many as four different visual opsin species belonging to three distinct classes. The combination of opsins with different spectral sensitivities and G protein selectivities may underlie physiological properties of the ocular photoreception, such as a shift in spectral sensitivity between dark- and light-adapted states. This may be allowed by adjustment of the relative contribution of the four opsins without neural networks, enabling a simple strategy for fine-tuning of vision. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-023-01789-7.

CITATION EXPORT

Ryota Matsuo, Mitsumasa Koyanagi, Tomohiro Sugihara et al.. Functional characterization of four opsins and two G alpha subtypes co-expressed in the molluscan rhabdomeric photoreceptor. BMC Biology. (2023). https://doi.org/10.1186/s12915-023-01789-7

AUTHORS

8 · 6 CENTRES

Ryota Matsuo, Mitsumasa Koyanagi, Tomohiro Sugihara, Taishi Shirata, Takashi Nagata, Keiichi Inoue, Yuko Matsuo, Akihisa Terakita

1https://ror.org/00skwgg83grid.411574.20000 0000 9681 1887International College of Arts and Sciences, Fukuoka Women’s University, 1-1-1 Kasumigaoka, Higashi-Ku, Fukuoka, 813-8529 Japan
2https://ror.org/01hvx5h04Department of Biology, Graduate School of Science, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-Ku, Osaka, 558-8585 Japan
3grid.518217.80000 0005 0893 4200Department of Biology and Geosciences, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-Ku, Osaka, 558-8585 Japan
4https://ror.org/01hvx5h04The OMU Advanced Research Institute of Natural Science and Technology, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-Ku, Osaka, 558-8585 Japan
5https://ror.org/057zh3y96grid.26999.3d0000 0001 2151 536XThe Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
6https://ror.org/00097mb19grid.419082.60000 0001 2285 0987PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan