Development of the virus vaccine by the elucidation of the virulence of a plant virus

为了阐明PAP对RNA的脱嘌呤作用机制，了解PAP识别和靶向不同RNA的机制，研究了PAP与芜菁花叶病毒基因组连接蛋白（VPg）的相互作用。VPg可以在帽非依赖性翻译中作为帽类似物起作用，并且潜在地将PAP靶向至未加帽的含IRES的RNA。本工作采用荧光光谱和HPLC技术定量研究PAP的脱嘌呤活性和PAP-VPg相互作用。PAP以高亲和力（29.5 nM）与VPg结合;该反应是热力学驱动的，并且熵有利。此外，VPg是小麦胚芽裂解物中RNA的PAP脱嘌呤的有效抑制剂，并且与来自烟草蚀纹病毒（TEV）的结构化RNA竞争PAP结合。VPg可能通过抑制植物防御机制之一而赋予进化优势，并且还表明可能使用这种蛋白质对抗RIP的细胞毒性活性。

To elucidate the mechanism of RNA depurination, and to understand how PAP recognizes and targets various RNAs, the interactions between PAP and Turnip mosaic virus genome linked protein (VPg) were investigated. VPg can function as a cap analog in cap-independent translation, and potentially target PAP to uncapped IRES-containing RNA. In this work, fluorescence spectroscopy and HPLC techniques were used to quantitatively describe PAP depurination activity and PAP-VPg interactions. PAP binds to VPg with high affinity (29.5 nM); the reaction is enthalpically driven and entropically favored. Further, VPg is a potent inhibitor of PAP depurination of RNA in wheat germ lysate, and competes with structured RNA derived from tobacco etch virus (TEV) for PAP binding. VPg may confer an evolutionary advantage by suppressing one of the plant defense mechanisms, and also suggests the possible use of this protein against the cytotoxic activity of RIPs.