State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China.
Virol J. 2011 Jan 18;8:24. doi: 10.1186/1743-422X-8-24.
Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus within the family Reoviridae, can infect several graminaceous plant species including rice, maize and wheat, and is transmitted by planthoppers. Although several RBSDV proteins have been studied in detail, functions of the nonstructural protein P6 are still largely unknown.
In the current study, we employed yeast two-hybrid assays, bimolecular fluorescence complementation and subcellular localization experiments to show that P6 can self-interact to form punctate, cytoplasmic viroplasm-like structures (VLS) when expressed alone in plant cells. The region from residues 395 to 659 is necessary for P6 self-interaction, whereas two polypeptides (residues 580-620 and 615-655) are involved in the subcellular localization of P6. Furthermore, P6 strongly interacts with the viroplasm-associated protein P9-1 and recruits P9-1 to localize in VLS. The P6 395-659 region is also important for the P6-P9-1 interaction, and deleting any region of P9-1 abolishes this heterologous interaction.
RBSDV P6 protein has an intrinsic ability to self-interact and forms VLS without other RBSDV proteins or RNAs. P6 recruits P9-1 to VLS by direct protein-protein interaction. This is the first report on the functionality of RBSDV P6 protein. P6 may be involved in the process of viroplasm nucleation and virus morphogenesis.
斐济病毒属（Fijivirus）呼肠孤病毒科（Reoviridae）的水稻黑条矮缩病毒（Rice black-streaked dwarf virus，RBSDV）可感染包括水稻、玉米和小麦在内的几种禾本科植物，通过叶蝉传播。尽管已经对几种 RBSDV 蛋白进行了详细研究，但非结构蛋白 P6 的功能仍知之甚少。
在本研究中，我们采用酵母双杂交分析、双分子荧光互补和亚细胞定位实验，证明当 P6 在植物细胞中单独表达时，它可以自我相互作用形成点状、细胞质类病毒体样结构（VLS）。残基 395 至 659 之间的区域是 P6 自我相互作用所必需的，而两个多肽（残基 580-620 和 615-655）参与 P6 的亚细胞定位。此外，P6 与类病毒体相关蛋白 P9-1 强烈相互作用，并募集 P9-1 定位于 VLS。P6 的 395-659 区域对于 P6-P9-1 相互作用也很重要，并且删除 P9-1 的任何区域都会破坏这种异源相互作用。
RBSDV P6 蛋白具有内在的自我相互作用能力，并在没有其他 RBSDV 蛋白或 RNA 的情况下形成 VLS。P6 通过直接的蛋白质-蛋白质相互作用募集 P9-1 到 VLS。这是关于 RBSDV P6 蛋白功能的首次报道。P6 可能参与类病毒体成核和病毒形态发生的过程。
