Near-Atomic-Resolution Cryo-Electron Microscopy Structures of Cucumber Leaf Spot Virus and Red Clover Necrotic Mosaic Virus: Evolutionary Divergence at the Icosahedral Three-Fold Axes.
Near-Atomic-Resolution Cryo-Electron Microscopy Structures of Cucumber Leaf Spot Virus and Red Clover Necrotic Mosaic Virus: Evolutionary Divergence at the Icosahedral Three-Fold Axes.
复制标题
黄瓜叶斑病毒和红三叶草坏死花叶病毒的近原子分辨率冷冻电子显微镜结构：二十面体三重轴的进化分歧。
DOI：
10.1128/jvi.01439-19
复制
发表时间：
2020
影响因子：
5.4
通讯作者：
Smith,ThomasJ
中科院分区：
文献类型：
--
作者：
Sherman,MichaelB;Guenther,Richard;Reade,Ron;Rochon,D'Ann;Sit,Tim;Smith,ThomasJ
tombusviridae家族的成员具有高度相似的结构，但它们之间在宿主、传播和衣壳稳定性方面存在重要差异。tombusviridae家族的病毒具有单链RNA （ssRNA）基因组，具有T=3个二十面体蛋白外壳，最大直径为~ 340 Å。每个衣壳蛋白由三个结构域组成：R （RNA结合），S（外壳）和P（突出）。在R结构域和S结构域之间是“手臂”区域，研究表明该区域在组装过程中起着关键作用。为了更好地了解结构差异和相似性的细节如何影响tombusviridav的生命周期，我们利用冷冻电子显微镜和图像重建方法分别测定了黄瓜叶斑病病毒（CLSV; genusAureusvirus）和红三叶草坏死花叶病毒（RCNMV; genusDianthovirus）的结构，分辨率分别为3.2 Å和2.9 Å。虽然壳结构域具有同源结构，但在二十面体三重轴和R结构域上的稳定相互作用差异很大。tombusviridae家族成员R结构域的异质性可能与相应基因组的大小和特征差异有关。我们认为R结构域/RNA相互作用的变化导致了β-环空不同的臂结构域相互作用。例如，RCNMV具有最大的基因组，它似乎通过进化最短的R结构域在衣壳中创造了必要的空间。由此导致的RNA/R结构域相互作用的损失可能通过在二十面体3重轴上增加亚基间β-链相互作用来补偿。因此，R结构域和arm结构域可能共同进化，将不同的基因组包装在保守的刚性外壳内。tombusviridae家族的成员具有几乎相同的外壳，但它们包装的基因组大小从4.6 kb（单侧）到5.3 kb（双侧）不等。为了了解这种基因组灵活性是如何在一个严格保守的壳内发生的，我们确定了黄瓜叶斑病病毒和红三叶草坏死花叶病毒的高分辨率冷冻电镜（cryo-EM）结构。作为对基因组大小差异的响应，衣壳的ssRNA结合域(R)似乎在进化上发生了分化，以识别不同的基因组。下一个区域，“臂”，似乎也与R域共同进化，允许粒子通过在二十面体三重轴上的相互作用进行组装。此外，在二十面体三重轴上存在金属结合的差异，这可能对传播和病毒生命周期很重要。
Members of theTombusviridaefamily have highly similar structures, and yet there are important differences among them in host, transmission, and capsid stabilities. Viruses in theTombusviridaefamily have single-stranded RNA (ssRNA) genomes with T=3 icosahedral protein shells with a maximum diameter of ∼340 Å. Each capsid protein is comprised of three domains: R (RNA binding), S (shell), and P (protruding). Between the R domain and S domain is the “arm” region that studies have shown to play a critical role in assembly. To better understand how the details of structural differences and similarities influence theTombusviridaeviral life cycles, the structures of cucumber leaf spot virus (CLSV; genusAureusvirus) and red clover necrotic mosaic virus (RCNMV; genusDianthovirus) were determined to resolutions of 3.2 Å and 2.9 Å, respectively, with cryo-electron microscopy and image reconstruction methods. While the shell domains had homologous structures, the stabilizing interactions at the icosahedral 3-fold axes and the R domains differed greatly. The heterogeneity in the R domains among the members of theTombusviridaefamily is likely correlated with differences in the sizes and characteristics of the corresponding genomes. We propose that the changes in the R domain/RNA interactions evolved different arm domain interactions at the β-annuli. For example, RCNMV has the largest genome and it appears to have created the necessary space in the capsid by evolving the shortest R domain. The resulting loss in RNA/R domain interactions may have been compensated for by increased intersubunit β-strand interactions at the icosahedral 3-fold axes. Therefore, the R and arm domains may have coevolved to package different genomes within the conserved and rigid shell.IMPORTANCEMembers of theTombusviridaefamily have nearly identical shells, and yet they package genomes that range from 4.6 kb (monopartite) to 5.3 kb (bipartite) in size. To understand how this genome flexibility occurs within a rigidly conserved shell, we determined the high-resolution cryo-electron microscopy (cryo-EM) structures of cucumber leaf spot virus and red clover necrotic mosaic virus. In response to genomic size differences, it appears that the ssRNA binding (R) domain of the capsid diverged evolutionarily in order to recognize the different genomes. The next region, the “arm,” seems to have also coevolved with the R domain to allow particle assembly via interactions at the icosahedral 3-fold axes. In addition, there are differences at the icosahedral 3-fold axes with regard to metal binding that are likely important for transmission and the viral life cycle.