马铃薯Y病毒调控和利用寄主磷酸磷脂酰肌醇的机制研究

A variety of (+) ssRNA viruses have been proved to regulate and utilize the host’s phosphoinositides, however it is unknown if a similar situation exists in the infection process of Potato virus Y (PVY). In our previous work, the NbSAC1 protein encoded by Nicotiana benthamiana was identified as interacting with 6K2 protein of PVY, and PVY was seriously impaired when NbSAC1 was knocked down. AtSAC1 encodes a phosphoinositide phosphatase, which promotes the dephosphorylation of PI(3,5)P2 to PI3P. Therefore, NbSAC1 was proposed to participate in the infection process of PVY via controlling the dynamic condition of cellular PI3P or PI(3,5)P2. Based on this assumption, we will further clarify the interaction domains of 6K2 and NbSAC1, and study how 6K2 regulates the function of NbSAC1 through interaction as well as its impact on the dynamic condition of PI3P or PI(3,5)P2, we will also study the function of PI3P or PI(3,5)P2 in the process of viral replication, intercellular movement and systemic infection. These works will reveal the mechanism of the regulation and utilization of PI3P or PI(3,5)P2 by PVY, thereby providing scientific evidences for understanding the functions of PIPs in the infection process of PVY.

多种(+) ssRNA病毒可调控和利用寄主磷酸磷脂酰肌醇（PIPs），但马铃薯Y病毒（PVY）侵染过程是否存在类似机制尚不清楚。申请人前期利用酵母双杂交方法发现PVY 6K2蛋白与本氏烟NbSAC1蛋白互作，沉默NbSAC1后PVY侵染受到抑制。拟南芥AtSAC1基因编码一个磷脂酰肌醇磷酸酶，可将PI(3,5)P2去磷酸化形成PI3P，推测NbSAC1通过调节胞内PI3P或PI(3,5)P2动态参与PVY侵染。在此基础上，本项目拟进一步明确6K2与NbSAC1的互作结构域；分析6K2如何通过互作调控NbSAC1蛋白功能，以及对胞内PI3P或PI(3,5)P2动态产生何种影响；分析PI3P或PI(3,5)P2在PVY复制、胞间运动、系统侵染过程中的作用。研究结果将揭示PVY调控和利用寄主PI3P或PI(3,5)P2的机制，为了解PIPs在PVY侵染过程中的功能提供科学依据。

多种+RNA病毒可调控寄主磷脂组分代谢，但马铃薯Y病毒（Potato virus Y，PVY）侵染过程中是否存在类似机制尚不清楚。本课题的研究目标是了解PVY调控寄主磷脂酸代谢的机制，并分析磷脂酸对病毒侵染的影响。通过脂质组学分析，我们发现PVY侵染后寄主磷脂酸含量迅速增高。进一步研究发现，PVY编码的6K2蛋白通过与寄主NbPLDα1互作提高其活性，导致胞内磷脂酸含量增高。磷脂酸含量增高后，可与WIPK/SIPK结合并促进其磷酸化转录因子WRKY8，进而上调下游抗病基因转录，并抑制病毒侵染。这些结果揭示了PVY调控寄主磷脂酸代谢的机制，以及磷脂酸在触发MAPK介导的抗病毒反应中的作用机制。此外，本课题研究发现，喷施磷脂酸即可激活植物MAPK介导的免疫反应，抑制细菌、真菌和病毒侵染。表明磷脂酸可以作为一种新型植物免疫诱抗剂，广泛应用于病毒、真菌和细菌性病害的防控。