云南番茄曲叶病毒C4蛋白与寄主因子NbDRM2互作抑制寄主转录水平基因沉默的研究

DNA胞嘧啶甲基化介导的转录水平基因沉默是寄主抵御双生病毒的有效策略之一，为抵抗寄主的防御，双生病毒能够编码一些病毒蛋白(如C4蛋白等)抵抗DNA胞嘧啶甲基化介导的转录水平基因沉默。然而，双生病毒蛋白抵抗寄主转录水平基因沉默的分子机制尚不清楚。本项目拟在发现云南番茄曲叶病毒(TLCYnV) C4 蛋白能够与寄主甲基循环中发挥重要作用的DNA甲基转移酶NbDRM2互作基础上，分析NbDRM2对TLCYnV侵染性的影响，确定 TLCYnV C4与NbDRM2互作对NbDRM2胞内分布的影响、对NbDRM2结合DNA能力的影响及对TLCYnV C4抑制TGS能力的影响。本项目旨在揭示双生病毒C4蛋白抑制转录水平基因沉默的分子机制，为双生病毒的防治提供理论依据。

Cytosine DNA methylation is an efficient defense strategy against geminiviruses,which leads to viral genome methylation and transcriptional gene silencing (TGS). As a counter-defense, geminiviruses encode viral proteins to suppress the viral genome methylation. However, the molecular mechanism by which viral protein contributes to TGS suppression remains largely unknown. This study finds that C4 protein encoded by Tomato leaf curl Yunnan virus (TLCYnV) interacts with NbDRM2, an important DNA methyltransferase in methyl cycle. We will dissect the influence of TLCYnV C4/NbDRM2 interaction on the cellular distribution of NbDRM2, and the DNA binding ability of NbDRM2. The effects of the interaction between TLCYnV C4 and NbDRM2 on suppressed methylation-mediated TGS by TLCYnV C4 will be analyzed. This study provides new insights into the molecular mechanism of how a geminiviral protein hijacks NbDRM2 to suppress NbDRM2-mediated viral genome methylation.