Curated Optogenetic Publication Database

Abstract: Decades of genetic, molecular and biochemical studies in plants have provided foundational knowledge about light sensory proteins and led to their application in synthetic biology. Optogenetic tools take advantage of the light switchable activity of plant photoreceptors to control intracellular signaling pathways. The recent discovery of the UV-B photoreceptor UV RESISTANCE LOCUS 8 in the model plant Arabidopsis thaliana opens up new avenues for light-controllable methodologies. In this review, we discuss current developments in optogenetic control by UV-B light and its signaling components, as well as rational considerations in the design and applications of UV-B-based optogenetic tools.

Abstract: The Arabidopsis thaliana protein UVR8 is a photoreceptor for ultraviolet-B. Upon ultraviolet-B irradiation, UVR8 undergoes an immediate switch from homodimer to monomer, which triggers a signalling pathway for ultraviolet protection. The mechanism by which UVR8 senses ultraviolet-B remains largely unknown. Here we report the crystal structure of UVR8 at 1.8 Å resolution, revealing a symmetric homodimer of seven-bladed β-propeller that is devoid of any external cofactor as the chromophore. Arginine residues that stabilize the homodimeric interface, principally Arg 286 and Arg 338, make elaborate intramolecular cation-π interactions with surrounding tryptophan amino acids. Two of these tryptophans, Trp 285 and Trp 233, collectively serve as the ultraviolet-B chromophore. Our structural and biochemical analyses identify the molecular mechanism for UVR8-mediated ultraviolet-B perception, in which ultraviolet-B radiation results in destabilization of the intramolecular cation-π interactions, causing disruption of the critical intermolecular hydrogen bonds mediated by Arg 286 and Arg 338 and subsequent dissociation of the UVR8 homodimer.