Crystal structure of the Epithiospecifier Protein, ESP from Arabidopsis thaliana provides insights into its product specificity
Crystal structure of the Epithiospecifier Protein, ESP from Arabidopsis thaliana provides insights into its product specificity
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来自拟南芥的表硫特异性蛋白 ESP 的晶体结构提供了对其产品特异性的见解
DOI：
10.1016/j.bbrc.2016.08.019
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发表时间：
2016
影响因子：
3.1
通讯作者：
Feng Yue
中科院分区：
文献类型：
--
作者：
Zhang Weiwei;Wang Wenhe;Liu Zihe;Xie Yongchao;Wang Hao;Mu Yajuan;Huang Yao;Feng Yue
特异蛋白是硫代葡萄糖苷-黑芥子酶系统的重要组成部分，介导植物对草食和病原体的防御。当组织被破坏时，硫代葡萄糖苷被黑芥子酶水解成不稳定的聚糖醛酸酯，然后聚糖醛酸酯会重新排列形成防御性的异硫氰酸酯。根据硫代葡萄糖苷的侧链结构和特异蛋白的类型，特异蛋白可以改变反应方向，形成其他产物，如简单腈、上皮腈和有机硫氰酸酯，而不是异硫氰酸酯。然而，各种指示蛋白不同产物谱的分子机制尚未完全了解。在本研究中，我们以2.3 Å分辨率解析了拟南拟南（marabidopsis thaliana, AtESP）上皮指示蛋白ESP的晶体结构。与先前已知的硫氰酸盐形成蛋白TFP （TaTFP）结构比较，发现AtESP与TaTFP具有不同的二聚化模式。此外，AtESP的活性位点口袋比TaTFP略大，两种蛋白的活性位点周围的几个残基不同，这可能是两种蛋白的产物谱不同的原因。总之，我们的结构研究为说明蛋白的分子机制提供了重要的见解，并揭示了它们不同产物谱的基础。
Specifier proteins are important components of the glucosinolate-myrosinase system, which mediate plant defense against herbivory and pathogen attacks. Upon tissue disruption, glucosinolates are hydrolyzed to instable aglucones by myrosinases, and then aglucones will rearrange to form defensive isothiocyanates. Specifier proteins can redirect this reaction to form other products, such as simple nitriles, epithionitriles and organic thiocyanates instead of isothiocyanates based on the side chain structure of glucosinolate and the type of the specifier proteins. Nevertheless, the molecular mechanism underlying the different product spectrums of various specifier proteins was not fully understood. Here in this study, we solved the crystal structure of the Epithiospecifier Protein, ESP fromArabidopsis thaliana(AtESP) at 2.3 Å resolution. Structural comparisons with the previously solved structure of thiocyanate forming protein, TFP fromThlaspi arvense(TaTFP) reveal that AtESP shows a dimerization pattern different from TaTFP. Moreover, AtESP harbors a slightly larger active site pocket than TaTFP and several residues around the active site are different between the two proteins, which might account for the different product spectrums of the two proteins. Together, our structural study provides important insights into the molecular mechanisms of specifier proteins and shed light on the basis of their different product spectrums.