Geminiviruses are major plant pathogens that threaten food security globally. They have a unique architecture built from two incomplete icosahedral particles, fused to form a geminate capsid. However, despite their importance to agricultural economies and fundamental biological interest, the details of how this is realized in 3D remain unknown. Here we report the structure of Ageratum yellow vein virus at 3.3 Å resolution, using single-particle cryo-electron microscopy, together with an atomic model that shows that the N-terminus of the single capsid protein (CP) adopts three different conformations essential for building the interface between geminate halves. Our map also contains density for ~7 bases of single-stranded DNA bound to each CP, and we show that the interactions between the genome and CPs are different at the interface than in the rest of the capsid. With additional mutagenesis data, this suggests a central role for DNA binding-induced conformational change in directing the assembly of geminate capsids.

中文翻译：

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使用cryo-EM的植物双生病毒的3.3Å结构。

双子病毒是威胁全球粮食安全的主要植物病原体。它们具有独特的结构，该结构由两个不完整的二十面体颗粒构建而成，融合在一起形成双壳衣壳。但是，尽管它们对农业经济和生物基本利益很重要，但如何在3D中实现这一点的细节仍然未知。在这里，我们使用单粒子冷冻电子显微镜报告了分辨率为3.3Å的香叶黄脉病毒的结构，以及一个原子模型，该模型显示了单个衣壳蛋白（CP）的N端采用了三种不同的构象，这些构象对于建立两半重叠的界面。我们的图谱还包含与每个CP结合的约7个碱基的单链DNA的密度，并且我们证明了基因组与CP之间的相互作用在界面上与衣壳的其余部分不同。有了其他诱变数据，这表明DNA结合诱导的构象变化在指导双壳衣壳的组装中起着核心作用。