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Active state structures of a bistable visual opsin bound to G proteins
Oliver Tejero1,2, Filip Pamula1,3, Mitsumasa Koyanagi4,5
1Laboratory of Biomolecular Research, PSI Center for Life Sciences, Villigen-PSI, Switzerland.
Nature Communications
|October 16, 2024
Summary
Researchers revealed the active structures of bistable opsins, like jumping spider rhodopsin isoform-1 (JSR1), bound to G proteins. This provides key insights into how these light-sensing proteins function as bidirectional photoswitches.
Area of Science:
- Structural Biology
- Molecular Biology
- Biophysics
Background:
- Opsins are G protein-coupled receptors (GPCRs) crucial for light detection and signal transduction across animals.
- Bistable opsins, unlike monostable opsins, can return to an inactive state by absorbing a second photon, functioning as bidirectional photoswitches.
- Understanding the activated structures of bistable opsins is essential for elucidating their unique photoactivation mechanisms.
Purpose of the Study:
- To determine the active state structures of a bistable opsin, jumping spider rhodopsin isoform-1 (JSR1).
- To investigate the interaction of JSR1 with its downstream signaling partners, Gi and Gq heterotrimers.
- To elucidate the mechanistic differences between monostable and bistable opsin activation.
Main Methods:
- X-ray crystallography or cryo-electron microscopy to determine high-resolution structures.
- Biochemical assays to confirm G protein binding and activation.
- Spectroscopic methods to analyze chromophore interactions and conformational changes.
Main Results:
- Presented the first active state structures of the bistable opsin JSR1 complexed with Gi and Gq heterotrimers.
- Revealed structural details of the JSR1 activation mechanism, highlighting differences from monostable opsins.
- Provided a structural basis for understanding JSR1's function as a bidirectional photoswitch.
Conclusions:
- The determined structures offer critical insights into the activation mechanisms of bistable opsins.
- These findings advance our understanding of light-sensing GPCRs and their roles in biological signaling.
- The study lays the groundwork for engineering bistable opsins as optogenetic tools for precise control of cellular signaling pathways.
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