用含水冷冻电镜技术测定的水稻矮缩病毒的三维结构

Three Dimensional Structure of Rice Dwarf Virus by Electron Cryomicroscopy

用含水冷冻电镜技术和计算机数据处理方法分别测定了水稻矮缩病毒（ＲＤＶ）完整颗粒和只含内壳层的颗粒的三维结构，其分辨率分别为２．６ｎｍ和３．３ｎｍ。从完整颗粒的结构中可以清晰地看到它的外壳层和内壳层的双层结构及其内部的ＲＮＡ或非结构蛋白质的电子密度。完整颗粒和内壳层的直径分别为６９．８ｎｍ和５４．０ｎｍ，外壳层和内壳层的厚度分别为６．９ｎｍ和２．５ｎｍ。外壳层表面的三角形剖分数Ｔ＝１３。外壳层由２６０个衣粒（三体）组成，因此共有７８０个蛋白质亚基。外壳层和内壳层上均有许多通道。内外壳层之间以及外壳层的衣粒之间是以一种十分新颖的联锁方式相互连接的。

The three -dimensional(3D)structure of intact rice dwarf virus(RDV)has been determined to2.6nmresolution by 400KV electron cryomicroscopy and computer reconstruction techniques.The intact virion of69. 8nm in diameter was seen to make up of an outer shell of 6.9nm in thickness and an inner shell of2.5nm in thickness at a diameter of 54nm.Theouter shell surface forms a T=13 icosahedral lattice withholes at 5-and 6-coordinated positions.The 780 capsomeres at local 3-fold positions appear trimeric. Theinterface between these two shells could be clearly delineated and the interaction was maintained by acylindrical density whose upper domain connects subunits of the trimeric capsomeres by an interlockingmechanism. The 3D structure of inner shell was also reconstructed to 3.3nm from 100KV images ofpurified inner shell particles,confirming our interpretation of the multilayer structure of intact RDV.