RICE DWARF VIRUS STRUCTURAL STUDIES

水稻矮缩病毒(RDV)是植物呼肠孤病毒属的一员。 侵染水稻的双壳dsrna病毒。与其 由于严重的经济原因，详细的生化特征 亚洲水稻感染的后果，RDV的结构信息 是稀有且有争议的。我们已经确定了三维 完整(有dsRNA)和空RDV(无RNA)颗粒的结构 25岁400千伏电子显微镜和计算机的分辨率 重建。呼肠孤病毒科成员水稻矮缩病毒 是一种dsRNA病毒。水稻植株受侵染减产 产量显著增加。700型飞机的三维结构 400千伏电子冷冻显微镜测定RDV宽衣壳和 计算机重建显示了两个独特的二十面体壳： 具有T=13二十面体点阵的外壳，由260组成 三聚体团簇和60个二聚体的T=1二十面体晶格。 这种对称性失配是由 准等效壳蛋白的底域 亚单位。推定单体亚基的计算质量 与46 kDa P8和114 kDa P3的归属一致 分别与主要的外壳蛋白和内壳蛋白结合。初级阶段 并比较了P8和VP7的三维结构 蓝舌病毒(BTV)，一种动物呼肠孤病毒。尽管他们的总体 序列同源性显示28%的同源性，质量密度在上部 P8的结构域与在 VP7的晶体结构。P8的较低结构域适合，但不太好 到VP7的α螺旋结构域，即使在允许扭曲之后也是如此 在这两个域之间。P8所见的结构变化表明 准等价规则的崩溃，尽管VP7遵循它 严格来说是这样。

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.