Biophysics of rhodopsins and optogenetics

Area of Science:

• Biophysics
• Molecular Biology
• Neuroscience

Background:

• Rhodopsins are photoreceptive proteins containing a retinal chromophore, found in animals and microbes.
• Animal rhodopsins are G protein-coupled receptors involved in vision.
• Microbial rhodopsins exhibit diverse functions, including ion transport, serving as light-gated channels or pumps.

Purpose of the Study:

• To review the biophysics of rhodopsins.
• To explore the relationship between rhodopsin structure-function and optogenetics.
• To highlight the importance of understanding microbial rhodopsins for future optogenetic applications.

Main Methods:

• Review of existing literature on rhodopsin biophysics and optogenetics.
• Analysis of the photoisomerization cycle of retinal chromophores in animal and microbial rhodopsins.
• Discussion of microbial rhodopsin mechanisms for ion transport.

Main Results:

• Rhodopsins utilize retinal photoisomerization (11-cis to all-trans or all-trans to 13-cis) for their functional cycle.
• Microbial rhodopsins function as light-gated ion channels or light-driven pumps.
• These microbial rhodopsins are key tools for neural excitation and silencing in optogenetics.

Conclusions:

• Microbial rhodopsins offer diverse functionalities beyond vision, particularly in ion transport.
• Understanding the molecular mechanisms of microbial rhodopsins is essential for advancing optogenetics.
• Rational exploitation of microbial rhodopsins promises future innovations in optogenetic tools.