Simian virus 40 VP1 capsid protein forms polymorphic assemblies in vitro
Simian virus 40 VP1 capsid protein forms polymorphic assemblies in vitro
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DOI：
10.1099/vir.0.19067-0
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发表时间：
2003-07-01
影响因子：
3.8
通讯作者：
Handa, K
中科院分区：
文献类型：
--
作者：
Kanesashi, SN;Ishizu, K;Handa, K
猿猴病毒40 （SV40）衣壳由SV40的主要蛋白VP1的72个五聚体组成。这些五聚体排列在一个T = 7d的二十面体表面晶格中，这是由五聚体之间三种适当排列的非等效相互作用维持的。然而，目前尚不清楚这些相互作用是如何实现的。本研究对重组VP1的体外组装进行了分析。电镜观察显示，这些重组VP1蛋白在不同的环境条件下组装成结构上多态的颗粒。当存在高浓度硫酸铵时，VP1五聚体有效地组装成病毒样颗粒（VLPs）。然而，在中性pH下，1 M NaCl和2 mM CaCl2存在时，VP1五聚体不仅形成VLPs，而且产生微小的T = 1二十面体颗粒和管状结构。CaCl2的排除导致了微小颗粒的排他性形成。相反，在pH为5的150 mM NaCl条件下，VP1五聚体只产生超长的管状结构。因此VP1是非常独特的，因为它可以组装成如此不同的结构。这些观察结果提供了有助于阐明SV40衣壳形成机制的线索。
The simian virus 40 (SV40) capsid is composed of 72 pentamers of VP1, the major protein of SV40. These pentamers are arranged in a T = 7d icosahedral surface lattice, which is maintained by three types of appropriately arranged, non-equivalent interactions between the pentamers. However, it remains unclear how these interactions are achieved. In this study, the in vitro assembly of recombinant VP1 was analysed. Electron microscopy observations revealed that these recombinant VP1 proteins assembled into structurally polymorphic particles depending on environmental conditions. VP1 pentamers assembled efficiently into virus-like particles (VLPs) when high concentrations of ammonium sulfate were present. However, in the presence of 1 M NaCl and 2 mM CaCl2 at neutral pH, VP1 pentamers formed not only VLPs but also produced tiny T = 1 icosahedral particles and tubular structures. The exclusion of CaCl2 resulted in the exclusive formation of tiny particles. In contrast, in the presence of 150 mM NaCl at pH 5, the VP1 pentamers produced only extraordinarily long tubular structures. VP1 is thus quite unique in that it can assemble into such diverse structures. These observations provide clues that will help elucidate the mechanisms underlying SV40 capsid formation.