Structural basis of ultraviolet-B perception by UVR8 |
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Authors: | Wu Di Hu Qi Yan Zhen Chen Wen Yan Chuangye Huang Xi Zhang Jing Yang Panyu Deng Haiteng Wang Jiawei Deng XingWang Shi Yigong |
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Affiliation: | Tsinghua-Peking Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China. |
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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?? 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. |
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