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Publication Abstract from PubMed

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 A resolution, revealing a symmetric homodimer of seven-bladed beta-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-pi 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-pi interactions, causing disruption of the critical intermolecular hydrogen bonds mediated by Arg 286 and Arg 338 and subsequent dissociation of the UVR8 homodimer.

Structural basis of ultraviolet-B perception by UVR8.,Wu D, Hu Q, Yan Z, Chen W, Yan C, Huang X, Zhang J, Yang P, Deng H, Wang J, Deng X, Shi Y Nature. 2012 Feb 29;484(7393):214-9. doi: 10.1038/nature10931. PMID:22388820^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.