乙型脑炎病毒非结构蛋白NS5的晶体结构研究

黄病毒科的黄病毒属包括登革、西尼罗、乙型脑炎（JEV）等重要虫媒病毒。该属病毒编码的重要非结构蛋白NS5，是所有病毒体系中唯一的甲基转移酶（MTase）与依赖RNA的RNA聚合酶（RdRP）的天然融合体。目前NS5相关研究中MTase与RdRP如何相互作用以及两者是否存在协同关系均不明确，RdRP与基因组RNA的相互作用亦不清晰。近年来MTase和RdRP的晶体结构已分别解析，但NS5整体蛋白以及RdRP-RNA复合物这两种重要晶体结构一直未有报道。最近我们以JEV NS5为研究对象首次解析了NS5整体蛋白的高分辨率晶体结构（尚未发表）。本项目将以此为基础，以X射线晶体学为主要手段，解析NS5整体蛋白其他构象以及RdRP-RNA复合物的晶体结构，探索MTase与RdRP可能存在的多种互作模式和功能上的协同，剖析RdRP实现RNA复制的分子机理，为针对NS5的抗病毒药物开发提供新的结构基础。

The Flavivirus genus of the Flaviviridae family includes important arboviruses such as dengue, West Nile, and Japanese encephalitis (JEV) viruses. The virally encoded non-structural protein NS5 is the only natural fusion of a methyltransferase (MTase) and an RNA-dependent RNA polymerase (RdRP). Currently, the interactions and cooperativity between MTase and RdRP remain elusive, and the understandings on RdRP-RNA interactions are relatively limited. In recent years, numerous crystal structures of flavivirus MTase and RdRP as individual enzymes were solved. However, NS5 as an integral protein still awaits high resolution structural information. Using JEV NS5, we recently solved the first high resolution crystal structure of integral NS5 (unpublished data). Building on this new structure, we seek to systematically investigate other possible function-related conformations of JEV NS5 and RdRP-RNA interactions using X-ray crystallography as the primary tool. Our work aims at the in-depth understanding of the interactions and cooperation between the MTase and RdRP, and the mechanistic dissection of viral RNA replication, thus providing new structural basis for antiviral drug development targeting flavivirus NS5.