大多数杆状和一些丝状植物病毒编码富含半胱氨酸的蛋白(CRP),在病毒毒力中起作用;然而,这些CRPs在病毒感染中的作用在很大程度上仍然未知.这里,我们使用大麦条纹花叶病毒(BSMV)作为模型来研究其CRP在病毒形态发生中的重要作用。CRP蛋白γb直接与BSMV外壳蛋白(CP)相互作用,γb中His-85位点上的突变预测会产生潜在的CCCH基序,或者暴露于病毒体表面的CP中His-13位点上的突变会消除锌结合活性及其相互作用。免疫金标记实验表明,γb以Zn2依赖性方式与杆状BSMV病毒体的表面结合,增强CP的RNA结合活性,促进病毒体组装和稳定性,表明γb与病毒体的Zn2依赖性物理缔合对于BSMV形态发生至关重要。有趣的是,不同的CRP与它们的杆状病毒体紧密结合是弗吉尼亚病毒科(不包括烟草病毒属)和贝病毒科的成员所采用的一般特征。一起,这些结果揭示了迄今为止未知的CRPs在病毒颗粒的组装和稳定性中的作用,扩大我们对病毒形态发生的分子机制的理解。
The majority of rod-shaped and some filamentous plant viruses encode a cysteine-rich protein (CRP) that functions in viral virulence; however, the roles of these CRPs in viral infection remain largely unknown. Here, we used barley stripe mosaic virus (BSMV) as a model to investigate the essential role of its CRP in virus
morphogenesis. The CRP protein γb directly interacts with BSMV coat protein (CP), the mutations either on the His-85 site in γb predicted to generate a potential CCCH motif or on the His-13 site in CP exposed to the surface of the virions abolish the zinc-binding activity and their interaction. Immunogold-labeling assays show that γb binds to the surface of rod-shaped BSMV virions in a Zn2+-dependent manner, which enhances the RNA binding activity of CP and facilitates virion assembly and stability, suggesting that the Zn2+-dependent physical association of γb with the virion is crucial for BSMV
morphogenesis. Intriguingly, the tightly binding of diverse CRPs to their rod-shaped virions is a general feature employed by the members in the families Virgaviridae (excluding the genus Tobamovirus) and Benyviridae. Together, these results reveal a hitherto unknown role of CRPs in the assembly and stability of virus particles, and expand our understanding of the molecular mechanism underlying virus
morphogenesis.