Tomato Yellow Leaf Curl Virus V2 Protein Plays a Critical Role in the Nuclear Export of V1 Protein and Viral Systemic Infection
Tomato Yellow Leaf Curl Virus V2 Protein Plays a Critical Role in the Nuclear Export of V1 Protein and Viral Systemic Infection
复制标题
DOI：
10.3389/fmicb.2020.01243
复制
发表时间：
2019-06
影响因子：
5.2
通讯作者：
Wenhao Zhao;Yinghua Ji;Shuhua Wu;Elizabeth Barton;Yongjian Fan;Xiaofeng Wang;Yi-jun Zhou
中科院分区：
文献类型：
--
作者：
Wenhao Zhao;Yinghua Ji;Shuhua Wu;Elizabeth Barton;Yongjian Fan;Xiaofeng Wang;Yi-jun Zhou
双生病毒是一类重要的环状单链DNA病毒，可引起农作物的毁灭性病害。双生病毒在细胞核中复制其基因组DNA。新合成的病毒DNA随后被转运到细胞质中，在病毒移动蛋白的帮助下通过胞间连丝移动到相邻细胞，并最终长距离移动以建立全身感染。因此，核质转运是双生病毒成功感染的关键。对于番茄黄化曲叶病毒（TYLCV），已知V1蛋白结合并穿梭病毒基因组DNA，但V2蛋白在此过程中的作用尚不清楚。在这里，我们报告，核定位的V1蛋白显着减少时，与V2蛋白共表达，V2促进V1蛋白的核输出依赖于宿主exportin-α和一个特定的V1-V2相互作用。化学抑制Exportin-α或V2蛋白第85位半胱氨酸的a取代，取消了V1-V2的相互作用，阻断了V1蛋白向核周区和细胞质的再分布。当将V2 C85 S突变掺入TYLCV感染性克隆中时，与野生型TYLCV相比，TYLCV-C85 S引起非常轻微症状的延迟发作，表明V1-V2相互作用以及因此V2介导的V1蛋白的核输出对于病毒传播和全身感染至关重要。我们的数据表明，V2蛋白在促进V1蛋白的核输出中起关键作用，可能是通过促进V1介导的TYLCV基因组DNA的核质转运，进而促进病毒的全身感染。由于双生病毒的复制和转录都发生在细胞核中，因此病毒基因组DNA进出受感染细胞的细胞核的运输对于成功的感染周期至关重要。然而，双生病毒的核输出仍然知之甚少，甚至更少的是知道的过程中的单分裂双生病毒。我们使用TYLCV，一个典型的单分裂双生病毒科的菜豆花叶病毒，检查核质运输。在本研究中，我们发现TYLCV V2能够将核定位的V1蛋白重新分配到核周区域。此外，V1蛋白的核输出依赖于V1-V2相互作用和宿主输出蛋白α。阻断V1-V2相互作用可抑制V2介导的V1蛋白再分布，降低TYLCV感染效率，并出现延迟和轻度症状。本研究为V2在V1蛋白核输出和TYLCV病毒系统感染中的作用提供了新的解释。
Geminiviruses are an important group of circular, single-stranded DNA viruses that cause devastating diseases in crops. Geminiviruses replicate their genomic DNA in the nucleus. The newly-synthesized viral DNA is subsequently transported to the cytoplasm, moved to adjacent cells through plasmodesmata with the help of viral movement proteins, and, ultimately, moved long-distance to establish systemic infection. Thus, the nucleocytoplasmic transportation is crucial for a successful infection by geminiviruses. For Tomato yellow leaf curl virus (TYLCV), the V1 protein is known to bind and shuttle viral genomic DNA, but the role of V2 protein in this process is still unclear. Here, we report that the nucleus-localized V1 protein dramatically decreases when co-expressed with V2 protein, and that V2-facilitated nuclear export of V1 protein depends on host exportin-α and a specific V1-V2 interaction. Chemical inhibition of exportin-α or a substitutions at cysteine 85 of V2 protein, which abolishes the V1-V2 interaction, blocks the promoted redistribution of V1 protein to the perinuclear region and the cytoplasm. When the V2C85S mutation is incorporated into a TYLCV infectious clone, the TYLCV-C85S causes delayed onset of very mild symptoms compared to wild-type TYLCV, indicating that the V1-V2 interaction and, thus, V2-mediated nuclear export of V1 protein is crucial for viral spread and systemic infection. Our data point to a critical role of the V2 protein in promoting the nuclear export of the V1 protein, likely by promoting V1-mediated nucleocytoplasmic transportation of TYLCV genomic DNA, and in turn, promoting viral systemic infection. Author summary As both replication and the transcription of geminiviruses occur in the nucleus, transportation of the viral genomic DNA into and out of the nucleus of the infected cells is essential for a successful infection cycle. However, the nuclear export of geminiviruses is still little known and even less is known about the process for monopartite geminiviruses. We use TYLCV, a typical monopartite begomovirus in the family Geminiviridae, to examine the nucleocytoplasmic transportation. In this study, we found TYLCV V2 is able to redistribute the nucleus-localized V1 protein to the perinuclear region. Moreover, the nuclear export of V1 protein is dependent on the V1-V2 interaction and host exportin-α. Blocking the V1-V2 interaction impeded the V2-mediated V1 protein redistribution and decrease TYLCV infection efficiency with delayed and mild symptoms. This report shows us a new explanation for the role of V2 in the nuclear export of V1 protein and TYLCV viral systemic infection.