cGs-cAMP signalling pathway; TcOp13; optogenetic modulation

Animals sense light primarily by an opsin-based photopigment composed of G-protein coupled receptor (GPCR) and a covalently bound chromophore retinal. Functional analyses provided evidence for the use of the Gs-cAMP signalling pathway in a small set of cnidarian opsins. We have shown that TcOp13 opsin from Tripedalia cystophora jellyfish is able to elicit a sustained and reproducible Gs signalling upon visible light stimulation. These results indicated that TcOp13 could serve as a valuable optogenetic tool, and that further modifications in TcOp13 protein sequence may enhance its sensitivity to light-induced stimulation. We performed site-directed mutagenesis of TcOp13 that generated mutant variants possessing unique biochemical properties. TcOp13 variants represent novel optogenetic tools for controlling Gs signalling that are highly sensitive and can be activated by a simple white light source. We envisage that optogenetic modulation of Gs-protein signalling pathway based on TcOp13 platform allows for efficient and inexpensive screening for pharmacologically active chemical compounds.