RICE DWARF VIRUS STRUCTURAL STUDIES

水稻矮缩病毒（Rice dwarf virus，RDV）是植物呼肠孤病毒属（Phytoreovirus）的成员，是一种重要的水稻矮缩病毒。 感染水稻作物的双壳dsRNA病毒。 相对于其 详细的生化表征，由于严重的经济 亚洲水稻感染的后果，RDV的结构信息 是稀缺的和有争议的。 我们已经确定了 完整（含dsRNA）和空RDV（无RNA）颗粒的结构 在25
400 kV电子低温显微镜和计算机分辨率 重建 水稻矮缩病毒（Rice dwarf virus，RDV）是呼肠孤病毒科的一种 是一种dsRNA病毒。 水稻植株的感染减少了作物产量 生产显著。 700的三维结构
通过400 kV电子低温显微镜测定的宽RDV衣壳， 计算机重建揭示了两个独特的二十面体壳： 具有由260个碳原子组成的T=13的二十面体晶格的外壳 三聚体簇和60个二聚体的内部T=1二十面体晶格。 这种对称性不匹配是由结构的变化， 在准等价物中的外壳蛋白质的底板结构域 亚单位。 假定的单体亚基的计算质量 与46 kDa P8和114 kDa P3的分配一致 主要的外壳和内壳蛋白。 主 并与VP7的三维结构进行了比较 蓝舌病毒（BTV），一种动物呼肠孤病毒。 虽然他们的整体 序列同源性显示出28%的同一性，上部的质量密度为 P8的结构域与β夹心结构域很好地匹配， VP7的晶体结构 P8的下结构域拟合得不太好， 甚至在允许扭转之后， 在两个领域之间。 P8的结构变化表明， 准等价规则的崩溃，尽管VP7遵循它 从严

Rice dwarf virus (RDV), a member of phytoreovirus genus, is a double-shelled dsRNA virus infecting rice crops. In contrast to its detailed biochemical characterization due to the severe economical consequence of rice infection in Asia, structural information on RDV is scarce and controversial. We have determined the three-dimensional structures of the full (with dsRNA) and empty RDV (no RNA) particles at 25
resolution by 400 kV electron cryomicroscopy and computer reconstruction. Rice dwarf virus (RDV), a member of the Reoviridae family, is a dsRNA virus. Infection of rice plants reduces crop production significantly. The three-dimensional structure of the 700
wide RDV capsid determined by 400 kV electron cryomicroscopy and computer reconstruction reveals two distinctive icosahedral shells: an outer shell having a T=13 icosahedral lattice composed of 260 trimeric clusters and an inner T=1 icosahedral lattice of 60 dimers. This symmetry mismatch is accommodated by structural variations in the floor domains of the outer shell proteins in the quasi-equivalent subunits. The calculated masses of the putative monomeric subunits are consistent with an assignment of the 46 kDa P8 and the 114 kDa P3 to the major outer and inner shell proteins respectively. The primary and three-dimensional structure of P8 are compared with those of VP7 of blue-tongue virus (BTV), an animal reovirus. Though their overall sequence homology shows 28% identity, the mass densities in the upper domain of P8 matches well with the beta sandwich domain seen in the crystal structure of VP7. The lower domain of P8 fits but less well to the alpha helical domain of VP7 even after allowing for twisting between the two domains. The structural variations seen P8 suggests a breakdown of the quasi-equivalence rule, though VP7 follows it strictly.