Cao Xueli, Du Bowen, Han Fengjiao, Zhou Yu, Ren Junhui, Wang Wenhe, Chen Zeliang, Zhang Yi
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing, China.
Department of Computational Chemistry, National Institute of Biological Sciences, Beijing, China.
Front Plant Sci. 2020 Feb 27;11:157. doi: 10.3389/fpls.2020.00157. eCollection 2020.
Chloroplastic glutamine phosphoribosylpyrophosphate amidotransferase (GPRATase) catalyzes the first committed step of purine biosynthesis in , and DAS734 is a direct and specific inhibitor of AtGPRAT, with phytotoxic effects similar to the leaf beaching phenotypes of known AtGPRAT genetic mutants, especially and . However, the structure of AtGPRAT and the inhibition mode of DAS734 still remain poorly understood. In this study, we solved the structure of AtGPRAT2, which revealed structural differences between AtGPRAT2 and bacterial enzymes. Kinetics assay demonstrated that DAS734 behaves as a competitive inhibitor for the substrate phosphoribosyl pyrophosphate (PRPP) of AtGPRAT2. Docking studies showed that DAS734 forms electrostatic interactions with R264 and hydrophobic interactions with several residues, which was verified by binding assays. Collectively, our study provides important insights into the inhibition mechanism of DAS734 to AtGPRAT2 and sheds light on future studies into further development of more potent herbicides targeting GPRATases.
叶绿体谷氨酰胺磷酸核糖焦磷酸酰胺转移酶（GPRATase）催化植物中嘌呤生物合成的第一步关键反应，而DAS734是拟南芥GPRAT（AtGPRAT）的直接特异性抑制剂，其植物毒性效应类似于已知AtGPRAT基因突变体的叶片白化表型，尤其是[具体突变体1]和[具体突变体2]。然而，AtGPRAT的结构以及DAS734的抑制模式仍知之甚少。在本研究中，我们解析了AtGPRAT2的结构，揭示了AtGPRAT2与细菌酶之间的结构差异。动力学分析表明，DAS734对AtGPRAT2的底物磷酸核糖焦磷酸（PRPP）表现为竞争性抑制剂。对接研究表明，DAS734与R264形成静电相互作用，并与多个残基形成疏水相互作用，这一结果通过结合实验得到了验证。总的来说，我们的研究为DAS734对AtGPRAT2的抑制机制提供了重要见解，并为未来针对GPRATases开发更有效的除草剂的研究提供了思路。
