Silencing Suppressor Protein VPg of a Potyvirus Interacts With the Plant Silencing-Related Protein SGS3
Silencing Suppressor Protein VPg of a Potyvirus Interacts With the Plant Silencing-Related Protein SGS3
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DOI：
10.1094/mpmi-04-14-0109-r
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发表时间：
2014-11-01
影响因子：
3.5
通讯作者：
Valkonen, Jari P. T.
中科院分区：
文献类型：
--
作者：
Rajamaki, Minna-Liisa;Streng, Janne;Valkonen, Jari P. T.
马铃薯Y病毒属的病毒基因组连接蛋白（VPg）参与马铃薯Y病毒属感染周期的多个步骤，包括病毒在植物中的增殖和移动。最近，我们发现，马铃薯病毒A（PVA;属马铃薯Y病毒）的VPG抑制有义介导的RNA沉默，这是连接到一个或两个核或核仁定位。在这里，我们研究了VPg和植物RNA沉默途径的组件之间的相互作用。结果表明，VPg与马铃薯和拟南芥的SGS 3蛋白相互作用，如酵母双杂交分析和双分子荧光互补分析所示。VPg SGS 3相互作用与含有植物RNA依赖性RNA聚合酶6（RDR 6）的小细胞质体（可能是SGS 3/RDR 6体）共定位。SGS 3的N端锌指结构域是VPg相互作用的主要决定因素。我们的数据还表明ZF结构域控制SGS 3定位。SGS 3同源二聚化受多个蛋白质区域控制。VPg SGS 3相互作用似乎对PVA有益，因为在本氏烟草的SGS 3沉默和SGS 3过表达叶片中病毒RNA水平与sgs 3 mRNA水平正相关。这些数据支持VPg作为RNA沉默的抑制因子的观点，并表明与SGS 3的相互作用可能是重要的，特别是在抑制有义介导的RNA沉默中。
Viral genome-linked protein (VPg) of potyviruses is involved in multiple steps of the potyvirus infection cycle, including viral multiplication and movement in plants. Recently, we showed that VPg of Potato virus A (PVA; genus Potyvirus) suppresses sense-mediated RNA silencing, which is linked to one or both nuclear or nucleolar localization. Here, we studied interactions between VPg and components of the plant RNA silencing pathway. Results showed that VPg interacts with the SGS3 protein of Solanum tuberosum and Arabidopsis thaliana, as shown by yeast two-hybrid analysis and bimolecular fluorescence complementation assays. VPg SGS3 interactions co-localized with small cytoplasmic bodies that contained plant RNA-dependent RNA polymerase 6 (RDR6) (likely SGS3/RDR6 bodies). The N-terminal zinc finger (ZF) domain of SGS3 was the main determinant of the VPg interaction. Our data also suggest that the ZF domain controls SGS3 localization. SGS3 homodimerization was controlled by multiple protein regions. The VPg SGS3 interaction appeared beneficial for PVA, as viral RNA levels correlated positively with sgs3 mRNA levels in the SGS3-silenced and SGS3-overexpressing leaves of Nicotiana benthamiana. The data support the idea that VPg acts as a suppressor of RNA silencing and suggest that an interaction with SGS3 may be important, especially in suppression of sense-mediated RNA silencing.