POLYMORPHISM IN THE ASSEMBLY OF POLYOMAVIRUS CAPSID PROTEIN VP1
POLYMORPHISM IN THE ASSEMBLY OF POLYOMAVIRUS CAPSID PROTEIN VP1
复制标题
DOI：
10.1016/s0006-3495(89)82735-3
复制
发表时间：
1989-11-01
影响因子：
3.4
通讯作者：
GARCEA, RL
中科院分区：
文献类型：
--
作者：
SALUNKE, DM;CASPAR, DLD;GARCEA, RL
多瘤病毒主要衣壳蛋白VP1在大肠杆菌中表达后纯化，在低离子强度、中性或碱性溶液中形成稳定的五聚体。电子显微镜显示，通过降低pH、添加钙或提高离子强度，与病毒衣壳相对应的五聚体可以自组装成各种不同形态的聚集体。一些聚集体类似于直径为500微安的病毒衣壳，而其他相当大或更小的衣壳也被产生。在过渡到有利于组装的环境时形成的特殊结构取决于溶剂变化的途径以及最终条件。低温电子显微镜的质量测量和负染样品的图像分析证实，一个独特的320 nm直径的粒子由24个紧密堆积的八面体对称性五聚体组成。用计算机图形学方法比较12壳二十面体聚集体和72壳二十面体病毒衣壳内的这种意想不到的八面体组装，表明这些不同大小的壳中的五聚体三聚体之间也有类似的连接。VP1五聚体组装的多态可能与构建病毒衣壳所需的结合特异性的转换有关。
Polyomavirus major capsid protein VP1, purified after expression of the recombinant gene in Escherichia coli, forms stable pentamers in low-ionic strength, neutral, or alkaline solutions. Electron microscopy showed that the pentamers, which correspond to viral capsomeres, can be self-assembled into a variety of polymorphic aggregates by lowering the pH, adding calcium, or raising the ionic strength. Some of the aggregates resembled the 500-.ANG.-diameter virus capsid, whereas other considerably larger or smaller capsids were also produced. The particular structures formed on transition to an environment favoring assembly depended on the pathway of the solvent changes as well as on the final conditions. Mass measurements from cryoelectron micrographs and image analysis of negatively stained specimens established that a distinctive 320-.ANG.-diameter particle consists of 24 close-packed pentamers arranged with octahedral symmetry. Comparison of this unexpected octahedral assembly within a 12-capsomere icosahedral aggregate and the 72-capsomere icosahedral virus capsid by computer graphics methods indicates that similar connections are made among trimers of pentamers in these shells of different size. The polymorphism in the assembly of VP1 pentamers can be related to the switching in bonding specificity required to build the virus capsid.