Evidence that SV40VP1-DNA interactions contribute to the assembly of 40-nm spherical viral particles
Evidence that SV40VP1-DNA interactions contribute to the assembly of 40-nm spherical viral particles
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DOI：
10.1111/j.1365-2443.2007.01134.x
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发表时间：
2007-11-01
期刊：
影响因子：
2.1
通讯作者：
Handa, Hiroshi
中科院分区：
文献类型：
--
作者：
Tsukamoto, Hiroko;Kawano, Masa-aki;Handa, Hiroshi
猴病毒40(SV40)颗粒主要由称为VP1的主要衣壳蛋白组成。VP1在细菌或昆虫细胞中过表达时可自组装成直径约40 nm的病毒样颗粒(VLP)，但纯化的VP1在生理条件下不会形成这种结构，因此，VP1组装的机制尚不清楚。使用一个高纯度的VP1体外组装/拆解系统，我们在这里提供了DNA是一个有助于VP1组装成40 nm球形颗粒的因素的证据。例如，在pH为5时，在DNA存在的情况下，VP1优先组装成40 nm的颗粒，而在没有DNA的情况下，VP1组装成管状结构。电子显微镜观察表明，DNA的浓度和长度对40 nm粒子的形成很重要。此外，蔗糖梯度沉淀法和DNase I敏感性分析表明，在所考察的条件下，DNA被包装在40 nm的颗粒中，其大小可达2000bp。我们认为DNA可能通过作为增加VP1局部浓度的支架和/或作为改变VP1结构的变构效应来促进40 nm球形颗粒的形成。
The simian virus 40 (SV40) particle is mainly composed of the major capsid protein termed VP1. VP1 self-assembles into virus-like particles (VLPs) of approximately 40 nm in diameter when over-expressed in bacteria or in insect cells, but purified VP1 does not form such a structure under physiological conditions, and thus, the mechanism of VP1 assembly is not well understood. Using a highly purified VP1 assembly/disassembly system in vitro, here we provide evidence that DNA is a factor that contributes to VP1 assembly into 40-nm spherical particles. At pH 5, for example, VP1 preferentially assembles into 40-nm particles in the presence of DNA, whereas VP1 assembles into tubular structures in the absence of DNA. Electron microscopic observations revealed that the concentration of DNA and its length are important for the formation of 40-nm particles. In addition, sucrose gradient sedimentation analysis and DNase I-sensitivity assays indicated that DNA of up to 2000 bp is packaged into the 40-nm particles under the conditions examined. We propose that DNA may facilitate the formation of 40-nm spherical particles by acting as a scaffold that increases the local concentration of VP1 and/or by acting as an allosteric effector that alters the structure of VP1.