Identification of Strawberry vein banding virus encoded P6 as an RNA silencing suppressor
Identification of Strawberry vein banding virus encoded P6 as an RNA silencing suppressor
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草莓脉带病毒编码 P6 作为 RNA 沉默抑制子的鉴定
DOI：
10.1016/j.virol.2018.05.003
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发表时间：
2018-07-01
期刊：
影响因子：
3.7
通讯作者：
Jiang, Tong
中科院分区：
文献类型：
--
作者：
Feng, Mingfeng;Zuo, Dengpan;Jiang, Tong
RNA沉默是一种常见机制，在抗病毒防御中发挥关键作用。为了克服宿主的防御反应，植物病毒编码沉默抑制蛋白，以靶向沉默机制中的一个或几个关键步骤。在这里，我们通过农杆菌介导的共渗透测定发现草莓静脉带状病毒（SVBV）编码的 P6 蛋白是一种 RNA 沉默抑制因子。 SVBV P6 蛋白可以抑制单链 RNA 诱导的绿色荧光蛋白 (GFP) 基因沉默，但不能抑制双链 RNA 诱导的绿色荧光蛋白 (GFP) 基因沉默。 P6蛋白还可以通过干扰GFP沉默信号的系统性传播来抑制GFP的系统性沉默。亚细胞定位研究表明，P6蛋白形成不规则小体，分布于本塞姆氏烟草细胞质和细胞核中。此外，缺失分析表明P6蛋白中的核定位信号（NLS，aa 402-426）负责沉默抑制效率。此外，通过基于马铃薯病毒X（PVX）的载体表达P6蛋白在本塞姆氏烟草叶片中诱导了更严重的花叶症状，并且表达P6的转基因本塞姆氏烟草植物表现出明显的叶脉黄化以及严重的叶片花叶症状。综上所述，我们的结果表明 SVBV P6 是 RNA 沉默的抑制因子，可能在 dsRNA 生成的上游步骤发挥作用。
RNA silencing is a common mechanism that plays a key role in antiviral defense. To overcome host defense responses, plant viruses encode silencing-suppressor proteins to target one or several key steps in the silencing machinery. Here, we report that the P6 protein encoded by Strawberry vein banding virus (SVBV) is an RNA silencing suppressor through Agrobacterium-mediated co-infiltration assays. SVBV P6 protein can suppress green fluorescent protein (GFP) gene silencing induced by single-stranded RNA but not by double-stranded RNA. The P6 protein can also inhibit systemic silencing of GFP through interfering the systemic spread of GFP silencing signal. Subcellular localization study indicated that P6 protein formed irregular bodies and distributed in both cytoplasm and nucleus of Nicotiana benthamiana cells. Furthermore, deletion analysis indicated that a nuclear localization signal (NLS, aa 402-426) in the P6 protein is responsible for the silencing suppression efficiency. In addition, expression of the P6 protein via a Potato virus X (PVX)-based vectors induced more severe mosaic symptoms in N. benthamiana leaves, and transgenic N. benthamiana plants expressing P6 showed obvious vein yellowing as well as severe mosaic symptoms in leaves. Taken together, our results demonstrates that SVBV P6 is a suppressor of RNA silencing, possibly acting at a upstream step for dsRNA generation.