流感病毒非结构蛋白NS1为多功能病毒蛋白分子，能通过与宿主因子互作干预宿主细胞正常功能。目前，NS1蛋白与诸多关键宿主因子复合物的结构仍待解析，以助于阐明NS1发挥其生物学功能的结构生物学机制。已有研究表明双链RNA结合蛋白STAUFEN1可与NS1结合，STAUFEN在果蝇和哺乳动物细胞中具有调控mRNA的定位、翻译及衰亡的作用。但NS1与STAUFEN具体如何发生相互作用，两者互作又如何调控病毒复制及影响宿主细胞的功能尚待探究。本项目拟采用GST pull-down、co-IP等方法精细确定NS1与STAUFEN间的结合区域，分析互作位点，同时确定RNA对两者互作的影响，解析稳定相互作用的两蛋白复合体结构。在复合物三维结构数据分析基础上，利用定点突变、过表达、RNAi及基因敲除、病毒反向遗传操作等方法，精确阐明NS1与STAUFEN相互作用对病毒复制和宿主细胞正常功能的影响。

The NS1 protein of influenza viruses is a multifunctional virulence factor. It can interfere with the host cell function by interaction with host factors. Currently, it is in great need to resolve the structures of protein complexes between NS1 and critical host factors in order to better elucidate the structural biological mechanism of how NS1 protein exerts its biological functions. Several studies have demonstrated that the double stranded RNA binding protein, STAUFEN1, is able to interact with the NS1 protein. The STAUFEN proteins act to modulate the localization, translation and decay of mRNA in drosophila and mammalian cells. However, it is still unclear how STAUFEN and NS1 interact with each other, and how their interaction modulates the virus replication and host cell function. In this project, we will employ the methodology of GST pull-down, co-immunoprecipitation etc., to narrow down the binding domain between STAUFEN and NS1 protein, analyze their interface and determine the effect of influenza mRNA on the interaction between NS1 and STAUFEN. After refining the functional interaction domain between STAUFEN and NS1, we will resolve the structure of the functional protein complex formed between NS1 and STAUFEN by crystallography. On the basis of the structural information, we will finally elucidate the mechanism of how the interaction between NS1 and STAUFEN regulates the influenza virus replication and host cell function by the methods of site-mutagenesis, gene overexpression, RNA interference, gene knock-out and reverse genetics of influenza virus.