A Functional Link between RNA Replication and Virion Assembly in the Potyvirus Plum Pox Virus
A Functional Link between RNA Replication and Virion Assembly in the Potyvirus Plum Pox Virus
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DOI：
10.1128/jvi.02179-17
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发表时间：
2018-05-01
影响因子：
5.4
通讯作者：
Antonio Garcia, Juan
中科院分区：
文献类型：
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作者：
Gallo, Araiz;Valli, Adrian;Antonio Garcia, Juan
马铃薯Y病毒属李痘病毒（PPV）中病毒颗粒的准确组装已显示取决于多功能病毒蛋白HCPro的贡献。在这项研究中，我们表明，其他病毒因子，除了衣壳蛋白（CP）和HCPro，是必要的形成稳定的PPV病毒粒子。本氏烟草叶中产生的CP来自称为LONG的亚病毒RNA，其表达缺少P1和HCPro的截短多蛋白，连同反式提供的HCPro一起组装成病毒样颗粒，并在体外孵育后保持稳定。相反，LONG编码序列多个区域的缺失阻止了HCPro介导的CP稳定化。特别是，我们证明了P3的前178个氨基酸，而不是编码它们的特定核苷酸序列，是CP稳定性和PPV颗粒正确组装所需的。利用连续凝固渗透试验，我们观察到亚病毒LONG RNA在N.表达RNA沉默抑制子的本萨米亚那叶。对LONG和全长PPV中影响RNA复制的点突变和缺失突变的影响进行的分析表明，该过程对于稳定病毒颗粒的组装至关重要。有趣的是，尽管有这种要求，由非复制型病毒RNA产生的CP可以稳定地组装成病毒体，只要它与复制型RNA共表达。总之，这些结果突出了耦合的重要性，其他病毒过程，以确保成功infection.IMPORTANCE马铃薯Y病毒科病毒是最危险的威胁之一，基本上每一个重要的作物，这种社会经济的相关性，使他们成为许多研究的主题。尽管如此，目前对控制病毒基因组被外壳蛋白包被的蛋白质和过程知之甚少。例如，在李痘病毒（马铃薯Y病毒属）的情况下，我们先前已经表明，多任务病毒因子HCPro在稳定病毒体的产生中起作用。在这里，通过使用这种马铃薯Y病毒作为模型，我们进一步表明，额外的因素也是必要的有效生产马铃薯Y病毒颗粒。更重要的是，对这些因素的全面筛选使我们确定了病毒复制和包装之间的功能联系，揭示了马铃薯Y病毒感染周期中这两个关键事件之间以前未知的联系。
Accurate assembly of viral particles in the potyvirus Plum pox virus (PPV) has been shown to depend on the contribution of the multifunctional viral protein HCPro. In this study, we show that other viral factors, in addition to the capsid protein (CP) and HCPro, are necessary for the formation of stable PPV virions. The CP produced in Nicotiana benthamiana leaves from a subviral RNA termed LONG, which expresses a truncated polyprotein that lacks P1 and HCPro, together with HCPro supplied in trans, was assembled into virus-like particles and remained stable after in vitro incubation. In contrast, deletions in multiple regions of the LONG coding sequence prevented the CP stabilization mediated by HCPro. In particular, we demonstrated that the first 178 amino acids of P3, but not a specific nucleotide sequence coding for them, are required for CP stability and proper assembly of PPV particles. Using a sequential coagroinfiltration assay, we observed that the subviral LONG RNA replicates and locally spreads in N. benthamiana leaves expressing an RNA silencing suppressor. The analysis of the effect of both point and deletion mutations affecting RNA replication in LONG and full-length PPV demonstrated that this process is essential for the assembly of stable viral particles. Interestingly, in spite of this requirement, the CP produced by a nonreplicating viral RNA can be stably assembled into virions as long as it is coexpressed with a replication-proficient RNA. Altogether, these results highlight the importance of coupling encapsidation to other viral processes to secure a successful infection.IMPORTANCE Viruses of the family Potyviridae are among the most dangerous threats for basically every important crop, and such socioeconomical relevance has made them a subject of many research studies. In spite of this, very little is currently known about proteins and processes controlling viral genome encapsidation by the coat protein. In the case of Plum pox virus (genus Potyvirus), for instance, we have previously shown that the multitasking viral factor HCPro plays a role in the production of stable virions. Here, by using this potyvirus as a model, we move further to show that additional factors are also necessary for the efficient production of potyviral particles. More importantly, a comprehensive screening for such factors led us to the identification of a functional link between virus replication and packaging, unraveling a previously unknown connection of these two key events of the potyviral infection cycle.