RICE DWARF VIRUS STRUCTURAL STUDIES

蓝舌病病毒（BTV）（呼肠孤病毒科，环状病毒属）是一种 无包膜二十面体双链RNA病毒。 几种蛋白 层包围基因组。 进入细胞后， 剥离，留下表面由VP 7组成的芯。 的 使用X射线衍射法测定了三聚体VP 7分子的结构 结晶学 连接的VP 7亚基由两个结构域组成， 一个主要是α-螺旋，另一个是较小的结构域， 熟悉的“滚动”拓扑。 它们的相对方向 两个畴以不同的晶体形式变化。 23分辨率地图 核心确定，使用电子低温显微镜（cryoEM）数据， 揭示了VP 7的260个三聚体组织在一个相当精确的T=13的分子上， 二十面体晶格 VP 7层占据了260
和 345
从核心的中心。 在此半径以下（230-260
）谎言 T=1层的120个VP 3分子。 通过拟合X射线结构 的单个VP 7三聚体的冷冻电镜结构，我们有 生成了BTV的VP 7层的原子模型，并演示了 在晶体中观察到的一种分子结构 VP 7对应于核心中分子的构象。 的 VP 7的β桶结构域位于核心的外部，并与 成熟病毒体外层的蛋白质。 下 VP 7的α-螺旋结构域与VP 3的内层相互作用。 T=13层中相邻的VP 7三聚体主要通过 在较宽的较低域中有明确的区域， 结构预期从准等价理论，没有 单个三聚体内的显著构象变化。 的 VP 3层决定了颗粒的大小，并形成了一个相当光滑的 VP 7三聚体的二维晶格位于其上的基底上， 躺下

Bluetongue virus (BTV) (Reoviridae family, Orbivirus genus) is a non-enveloped, icosahedral double-stranded RNA virus. Several protein layers enclose the genome. Upon cell entry the outer layer is stripped away leaving a core whose surface is composed of VP7. The structure of the trimeric VP7 molecule has been determined using X-ray crystallography. The articulated VP7 subunit consists of two domains, one largely alpha-helical and the other a smaller domain with the familiar 'jelly-roll' topology. The relative orientations of these two domains vary in different crystal forms. A 23 resolution map of the core determined, using electron cryo microscopy (cryoEM) data, reveals 260 trimers of VP7 organized on a rather precise T=13 laevo icosahedral lattice. The VP7 layer occupies a shell between 260
and 345
from the center of the core. Below this radius (230-260
) lies the T=1 layer of 120 molecules of VP3. By fitting the X-ray structure of the individual VP7 trimer to the cryoEM structure, we have generated an atomic model of the VP7 layer of BTV and demonstrated that one of the molecular structures seen in crystals of the isolated VP7 corresponds to the conformation of the molecule in the core. The beta barrel domains of VP7 are external to the core and interact with the protein in the outer layer of the mature virion. The lower alpha-helical domains of VP7 interact with the inner layer of VP3. Adjacent VP7 trimers in the T=13 layer interact principally through well defined regions in the broader lower domains and conform well to the structure expected from the theory of quasi-equivalence, with no significant conformational changes within the individual trimers. The VP3 layer determines the particle size and forms a rather smooth substrate upon which the two dimensional lattice of VP7 trimers is laid down.