Key Laboratory for the Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China.
J Virol. 2014 Mar;88(6):3223-34. doi: 10.1128/JVI.03006-13. Epub 2014 Jan 3.
The NSvc2 glycoproteins encoded by Rice stripe tenuivirus (RSV) share many characteristics common to the glycoproteins found among Bunyaviridae. Within this viral family, glycoproteins targeting to the Golgi apparatus play a pivotal role in the maturation of the enveloped spherical particles. RSV particles, however, adopt a long filamentous morphology. Recently, RSV NSvc2 glycoproteins were shown to localize exclusively to the ER in Sf9 insect cells. Here, we demonstrate that the amino-terminal NSvc2 (NSvc2-N) targets to the Golgi apparatus in Nicotiana benthamiana cells, whereas the carboxyl-terminal NSvc2 (NSvc2-C) accumulates in the endoplasmic reticulum (ER). Upon coexpression, NSvc2-N redirects NSvc2-C from the ER to the Golgi bodies. The NSvc2 glycoproteins move together with the Golgi stacks along the ER/actin network. The targeting of the NSvc2 glycoproteins to the Golgi bodies was strictly dependent on functional anterograde traffic out of the ER to the Golgi bodies or on a retrograde transport route from the Golgi apparatus. The analysis of truncated and chimeric NSvc2 proteins demonstrates that the Golgi targeting signal comprises amino acids 269 to 315 of NSvc2-N, encompassing the transmembrane domain and 24 adjacent amino acids in the cytosolic tail. Our findings demonstrate for the first time that the glycoproteins from an unenveloped Tenuivirus could target Golgi bodies in plant cells.
NSvc2 glycoprotein encoded by unenveloped Rice stripe tenuivirus (RSV) share many characteristics in common with glycoprotein found among Bunyaviridae in which all members have membrane-enveloped sphere particle. Recently, RSV NSvc2 glycoproteins were shown to localize exclusively to the ER in Sf9 insect cells. In this study, we demonstrated that the RSV glycoproteins could target Golgi bodies in plant cells. The targeting of NSvc2 glycoproteins to the Golgi bodies was dependent on active COP II or COP I. The Golgi targeting signal was mapped to the 23-amino-acid transmembrane domain and the adjacent 24 amino acids of the cytosolic tail of the NSvc2-N. In light of the evidence from viruses in Bunyaviridae that targeting Golgi bodies is important for the viral particle assembly and vector transmission, we propose that targeting of RSV glycoproteins into Golgi bodies in plant cells represents a physiologically relevant mechanism in the maturation of RSV particle complex for insect vector transmission.
由水稻条纹病毒（RSV）编码的 NSvc2 糖蛋白与 Bunyaviridae 中发现的糖蛋白具有许多共同特征。在这个病毒家族中，靶向高尔基体的糖蛋白在包膜球形颗粒的成熟中起着关键作用。然而，RSV 颗粒采用长丝状形态。最近，RSV NSvc2 糖蛋白被证明仅在 Sf9 昆虫细胞中定位于内质网。在这里，我们证明氨基末端 NSvc2（NSvc2-N）靶向烟草原生质体细胞中的高尔基体，而羧基末端 NSvc2（NSvc2-C）则积累在内质网（ER）中。共表达时，NSvc2-N 将 NSvc2-C 从 ER 重定向到高尔基体。NSvc2 糖蛋白与高尔基体堆栈一起沿着内质网/肌动蛋白网络移动。NSvc2 糖蛋白向高尔基体的靶向严格依赖于从 ER 到高尔基体的功能正向运输，或者依赖于从高尔基体的逆行运输途径。对截断和嵌合 NSvc2 蛋白的分析表明，高尔基体靶向信号包含 NSvc2-N 的 269 至 315 个氨基酸，包含跨膜结构域和细胞质尾部中的 24 个相邻氨基酸。我们的研究结果首次证明，无包膜 Tenuivirus 的糖蛋白可以在植物细胞中靶向高尔基体。
未包膜的水稻条纹病毒（RSV）编码的 NSvc2 糖蛋白与 Bunyaviridae 中的糖蛋白有许多共同特征，其中所有成员都有膜包膜的球形颗粒。最近，RSV NSvc2 糖蛋白被证明仅在 Sf9 昆虫细胞中定位于内质网。在这项研究中，我们证明了 RSV 糖蛋白可以靶向植物细胞中的高尔基体。NSvc2 糖蛋白向高尔基体的靶向依赖于活跃的 COP II 或 COP I。高尔基体靶向信号被映射到 NSvc2-N 的 23 个氨基酸跨膜结构域和细胞质尾部的相邻 24 个氨基酸。鉴于 Bunyaviridae 病毒的证据表明靶向高尔基体对于病毒颗粒组装和载体传播很重要，我们提出 RSV 糖蛋白在植物细胞中靶向高尔基体代表了昆虫载体传播中 RSV 颗粒复合物成熟的生理相关机制。
