1月31日，英国著名杂志《核酸研究 (Nuclear Acid Research) 》在线发表了上海生命科学研究院生物化学与细胞生物学研究所丁建平组关于色氨酰tRNA合成酶(TrpRS)的最新研究成果。氨酰tRNA合成酶负责将特定的氨基酸转移到相应的tRNA分子的氨基酸接受臂上，保证蛋白的正确翻译。丁建平组围绕色氨酰tRNA合成酶的底物特异性识别机制、催化机理、活性调节机制，以及TrpRS与结构上高度相似的苯丙氨酰tRNA合成酶TyrRS的进化关系等开展了系统的研究工作，已发表了一系列文章。最新进展进一步揭示了真核TrpRS的催化机制，并为针对TrpRS的抗真菌药物设计提供了新方向。
对原核生物TrpRS的结构研究表明，在ATP激活氨基酸的反应中，原核生物TrpRS采取了dissociative的催化机制。但是真核TrpRS的催化机制并不清楚。丁建平组博士生周旻昀和董咸池等人解析了酿酒酵母TrpRS的原酶结构，以及代表TrpRS催化反应中各个阶段的与底物、底物类似物和中间产物的复合物的晶体结构。在每个复合物结构中，在底物结合口袋处观察到一个硫酸根离子，分别模拟反应过程中ATP磷酸根离子的不同中间状态。此外，利用人源TrpRS与ATP和色氨酸的结构模型进行了分子动力学模拟。综合结构研究和分子动力学模拟的结果，揭示了真核TrpRS色氨酸激活反应采取与原核TrpRS不同的associtative的催化机制，并发现一个真核生物特有的保守精氨酸对于氨基酸激活反应具有关键性作用。另外，首次发现了真菌TrpRS和人TrpRS催化活性中心的差异，对于针对TrpRS的抗真菌药物设计具有指导作用。（Bioon.com）
丁建平研究员今年研究成果：
J.Immunology：治疗性抗体Basiliximab抑制IL-2信号通路的分子基础
NAR：色氨酰tRNA合成酶起源研究
Structure：小G蛋白与效应蛋白作用新方式
PNAS：单克隆抗体药物Efalizumab治疗银屑病的分子基础
JBC：发现新的抑制Caspase-3活性物质
生物谷推荐原始出处：
Nucleic Acids Research, doi:10.1093/nar/gkp1254
Crystal structures of Saccharomyces cerevisiae tryptophanyl-tRNA synthetase: new insights into the mechanism of tryptophan activation and implications for anti-fungal drug design
Minyun Zhou1,2, Xianchi Dong1,2, Ning Shen1, Chen Zhong1,* and Jianping Ding1,*
1State Key Laboratory of Molecular Biology and Research Center for Structural Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and 2Graduate School of Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
Specific activation of amino acids by aminoacyl-tRNA synthetases is essential for maintaining translational fidelity. Here, we present crystal structures of Saccharomyces cerevisiae tryptophanyl-tRNA synthetase (sTrpRS) in apo form and in complexes with various ligands. In each complex, there is a sulfate ion bound at the active site which mimics the - or β-phosphate group of ATP during tryptophan activation. In particular, in one monomer of the sTrpRS–TrpNH2O complex, the sulfate ion appears to capture a snapshot of the -phosphate of ATP during its movement towards tryptophan. Simulation study of a human TrpRS–Trp–ATP model shows that during the catalytic process the -phosphate of ATP is driven to an intermediate position equivalent to that of the sulfate ion, then moves further and eventually fluctuates at around 2 ? from the nucleophile. A conserved Arg may interact with the oxygen in the scissile bond at the transition state, indicating its critical role in the nucleophilic substitution. Taken together, eukaryotic TrpRSs may adopt an associative mechanism for tryptophan activation in contrast to a dissociative mechanism proposed for bacterial TrpRSs. In addition, structural analysis of the apo sTrpRS reveals a unique feature of fungal TrpRSs, which could be exploited in rational antifungal drug design.
