Self-Assembly of Epstein-Barr Virus Capsids
Self-Assembly of Epstein-Barr Virus Capsids
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DOI：
10.1128/jvi.01733-08
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发表时间：
2009-04-15
影响因子：
5.4
通讯作者：
Desai, Prashant
中科院分区：
文献类型：
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作者：
Henson, Brandon W.;Perkins, Edward M.;Desai, Prashant
爱泼斯坦-巴尔病毒(Epstein-Barr Virus，EBV)是伽马疱疹病毒家族的一员，主要感染B淋巴细胞，并与许多淋巴增生性疾病有关。这种淋巴病毒的组装途径的分子遗传学和衣壳的高分辨结构分析尚未确定。作为研究EB病毒衣壳组装的第一步，利用杆状病毒表达载体(BEV)表达了衣壳蛋白BcLF1(主要衣壳蛋白)、BORF1(三链蛋白)、BDLF1(三链蛋白)和BFRF3(小衣壳蛋白)、内支架蛋白BdRF1和成熟蛋白酶(BVRF2)。用电子显微镜和沉淀法判断，6种表达这些蛋白的病毒与昆虫细胞共感染后，可产生封闭的衣壳结构。因此，与其他疱疹病毒一样，EBV衣壳组装只需要6种蛋白质。此外，与卡波西肉瘤相关疱疹病毒一样，EBV的小衣壳蛋白(BFRF3)被发现是组装稳定结构所必需的。将小衣壳蛋白定位到核组装部位需要主要衣壳蛋白(BcLF1)和支架蛋白(BdRF1)，但不需要三链蛋白。BFRF3的突变分析表明，该多肽的N-末端部分(氨基酸1-88)是衣壳组装所必需的，并且足以组装衣壳。BFRF3在亚核部位的浓缩需要一个跨越65到88个氨基酸的区域，N-末端65个氨基酸包含与主要衣壳蛋白相互作用所需的序列。这些研究已经确定了伽马疱疹病毒小衣壳蛋白的多功能作用。
Epstein-Barr virus (EBV), a member of the Gammaherpesvirus family, primarily infects B lymphocytes and is responsible for a number of lymphoproliferative diseases. The molecular genetics of the assembly pathway and high-resolution structural analysis of the capsid have not been determined for this lymphocryptovirus. As a first step in studying EBV capsid assembly, the baculovirus expression vector (BEV) system was used to express the capsid shell proteins BcLF1 ( major capsid protein), BORF1 ( triplex protein), BDLF1 ( triplex protein), and BFRF3 ( small capsid protein); the internal scaffold protein, BdRF1; and the maturational protease ( BVRF2). Coinfection of insect cells with the six viruses expressing these proteins resulted in the production of closed capsid structures as judged by electron microscopy and sedimentation methods. Therefore, as shown for other herpesviruses, only six proteins are required for EBV capsid assembly. Furthermore, the small capsid protein of EBV ( BFRF3), like that of Kaposi's sarcoma-associated herpesvirus, was found to be required for assembly of a stable structure. Localization of the small capsid protein to nuclear assembly sites required both the major capsid ( BcLF1) and scaffold proteins ( BdRF1) but not the triplex proteins. Mutational analysis of BFRF3 showed that the N-terminal half ( amino acids 1 to 88) of this polypeptide is required and sufficient for capsid assembly. A region spanning amino acids 65 to 88 is required for the concentration of BFRF3 at a subnuclear site and the N-terminal 65 amino acids contain the sequences required for interaction with major capsid protein. These studies have identified the multifunctional role of the gammaherpesvirus small capsid proteins.