Structural basis of ultraviolet-B perception by UVR8
Structural basis of ultraviolet-B perception by UVR8
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DOI：
10.1038/nature10931
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发表时间：
2012-04-12
期刊：
影响因子：
64.8
通讯作者：
Shi, Yigong
中科院分区：
文献类型：
--
作者：
Wu, Di;Hu, Qi;Shi, Yigong
拟南芥蛋白UVR 8是紫外线-B的光感受器。在紫外线-B照射后，UVR 8经历从同二聚体到单体的立即转换，这触发了紫外线防护的信号通路。UVR 8感知紫外线B的机制在很大程度上仍然未知。在这里，我们报告的晶体结构的UVR 8在1.8埃分辨率，揭示了对称的同源二聚体的七叶片β-螺旋桨，没有任何外部辅因子作为发色团。稳定同源二聚体界面的精氨酸残基，主要是Arg 286和Arg 338，与周围的色氨酸氨基酸产生复杂的分子内阳离子-π相互作用。其中两个色氨酸，色氨酸285和色氨酸233，共同作为紫外线-B生色团。我们的结构和生物化学分析确定了UVR 8介导的紫外线-B感知的分子机制，其中紫外线-B辐射导致分子内阳离子-π相互作用的不稳定，导致由Arg 286和Arg 338介导的关键分子间氢键的破坏，以及随后的UVR 8同源二聚体的解离。
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 angstrom 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.