Crystallographic evidence for water-assisted photo-induced peptide cleavage in the stony coral fluorescent protein kaede
Crystallographic evidence for water-assisted photo-induced peptide cleavage in the stony coral fluorescent protein kaede
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DOI：
10.1016/j.jmb.2007.06.037
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发表时间：
2007-09-28
影响因子：
5.6
通讯作者：
Ikura, Mitsuhiko
中科院分区：
文献类型：
--
作者：
Hayashi, Ikuko;Mizuno, Hideaki;Ikura, Mitsuhiko
珊瑚荧光蛋白是一种珊瑚荧光蛋白，含有His62-Tyr63-Gly64三肽，形成一个绿色荧光的发色团。这个发色团的荧光在紫外光照射后变成红色。我们以前已经证明，这种光转化是通过正式的β-消除反应实现的，该反应导致在His62处发现的酰胺氮和a-碳之间的肽键断裂。然而，生色团的立体化学排列和这一反应机理的确切结构基础以前仍不清楚。在这里，我们报道了分别在1.4埃和1.6埃分辨率下的绿型和红型凯德的晶体结构。我们的结构以红色形式描绘了裂解的多肽键。绿色和红色形式的发色团构象相似，除了绿色形式的His62咪唑环附近有一个明确的水分子。我们提出了一种在水分子的辅助下实现绿光转化为红光的分子机制。(C)2007爱思唯尔有限公司。保留所有权利。
A coral fluorescent protein from Trachyphyllia geoffroyi, Kaede, possesses a tripeptide of His62-Tyr63-Gly64, which forms a chromophore with green fluorescence. This chromophore's fluorescence turns red following UV light irradiation. We have previously shown that such photoconversion is achieved by a formal beta-elimination reaction, which results in a cleavage of the peptide bond found between the amide nitrogen and the a-carbon at His62. However, the stereochemical arrangement of the chromophore and the precise structural basis for this reaction mechanism previously remained unknown. Here, we report the crystal structures of the green and red form of Kaede at 1.4 angstrom and 1.6 angstrom resolutions, respectively. Our structures depict the cleaved peptide bond in the red form. The chromophore conformations both in the green and red forms are similar, except a well-defined water molecule in the proximity of the His62 imidazole ring in the green form. We propose a molecular mechanism for green-to-red photoconversion, which is assisted by the water molecule. (c) 2007 Elsevier Ltd. All rights reserved.