甲型流感病毒HA跨膜区的结构以及与膜脂相互作用的核磁共振研究

Seasonal influenza seriously threatens global public health, causing 3-5 million severe illness and 290,000 to 650,000 deaths each year worldwide. Influenza viruses infect host cells through virus-cell membrane fusion mediated by its glycoprotein hemagglutinin (HA), which is anchored to the virus envelope by transmembrane domain (TMD) and is the primary target of influenza vaccines and antiviral drugs. HA TMD plays a critical role during viral fusion, if replace the TMD by glycosylphosphatidylinositol, which is a lipid anchor only, the fusion will be blocked. However, little is known about the molecular basis of TMD functioning in the membrane fusion. Based on our previous studies on the membrane-bound regions of parainfluenza virus fusion protein, this project aims to determine the structures, depth of insertion, oligomer assembly and dynamics of HA TMD in membrane-mimicking environments and various lipid bilayers by using liquid-state and solid-state NMR spectroscopy. The impact of TMD on the curvature and hydration of the lipid membranes will also be investigated. The study will elucidate the structure basis for the roles of TMD in the membrane fusion and propose a virus-cell fusion model involving HA TMD, and it will provide the theoretical basis for the development of antiviral drugs and universal vaccines.

季节性流感严重危害人类的健康，每年引起全球数百万例肺炎并导致数十万人死亡。流感病毒感染宿主细胞依赖于其表面糖蛋白血凝素（HA）所介导的病毒膜和细胞脂膜的融合。HA通过跨膜区锚定在病毒包膜上，是流感疫苗和抗病毒药物研制的重要靶标。HA的跨膜区在病毒膜融合过程中发挥重要功能，如将跨膜区替换为仅起锚定作用的糖基磷脂酰肌醇，融合会被阻断，然而跨膜区调控脂膜融合的分子基础尚不清楚。本项目基于前期在副流感病毒融合蛋白膜结合区的研究工作基础上，应用液体和固体核磁共振技术，测定HA的跨膜区在类膜和脂双层膜环境中的结构、定位、寡聚组装和动力学特征，研究跨膜区对脂膜构象和表面水的影响，揭示跨膜区调控脂膜融合的结构基础，建立跨膜区参与下的流感病毒-细胞膜融合模型，为研发抗病毒药物和广谱疫苗提供理论依据。

流感病毒感染宿主细胞通过其表面糖蛋白血凝素（HA）所介导的病毒膜和细胞脂膜的融合。HA通过跨膜区锚定在病毒包膜上，是流感疫苗和抗病毒药物研制的重要靶标。HA的跨膜区在病毒膜融合过程中发挥重要功能，然而跨膜区调控脂膜融合的分子基础尚不清楚。本项目构建了不同跨膜区片段，通过核磁共振和圆二色研究其结构以及与脂膜的相互作用，发现HA跨膜区不同于HIV和PIV5的融合蛋白跨膜区会改变PE脂膜构象，HA跨膜区可能与胆固醇和PS脂膜作用。结构研究发现近膜区MPER和跨膜区TMD在类膜环境呈现alpha-螺旋结构，而胞内区CT呈现beta-链结构。HA跨膜区相关区域不同的结构倾向很可能与其特殊功能有关。