Mutational analysis of essential interactions involved in the assembly of hepatitis E virus capsid
Mutational analysis of essential interactions involved in the assembly of hepatitis E virus capsid
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DOI：
10.1074/jbc.m410361200
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发表时间：
2005-02-04
影响因子：
4.8
通讯作者：
Xia, NS
中科院分区：
文献类型：
--
作者：
Li, SW;Zhang, J;Xia, NS
戊型肝炎病毒(HEV)衣壳由单一结构蛋白组成，其中一部分以等面体接触形成基壳，另一部分以二聚体接触形成从壳伸出的同源二聚体。以往的研究表明，截短的HEV衣壳蛋白的同源二聚体E2(氨基酸394-606)和P239(氨基酸368-606)模拟HEV的优势抗原决定簇。用这些蛋白免疫恒河猴可以保护猕猴免受病毒的攻击，三种针对同源二聚体的单抗可以中和HEV的感染性和/或对病毒的免疫捕获。此外，p239的同源二聚体进一步相互作用形成直径23 nm的颗粒，使其成为有效的候选疫苗。有鉴于此，我们推测形成同源二聚体和颗粒的相互作用可能类似于组装病毒衣壳的作用。目前，已经进行了突变分析来确定这些相互作用的位置。二聚体相互作用的位置位于6个疏水氨基酸残基的簇上，即Ala(597)、Val(598)、Ala(599)、Leu(601)和Ala(602)；此外，参与颗粒形成的位置位于氨基酸368-394。这些位点也参与病毒衣壳组装的可能性得到了以下事实的支持，即它们位于HEV结构蛋白的两个主要且高度保守的疏水区。
The hepatitis E virus (HEV) capsid consists of a single structural protein, a portion of which is engaged in isosahedral contact to form a basal shell, and another portion in dimeric contact to form the homodimers protruding from the shell. Previous studies revealed that homodimers of the truncated HEV capsid proteins, E2 (amino acids 394-606) and p239 (amino acids 368-606), model dominant antigenic determinants of HEV. Immunization with these proteins protected rhesus monkeys against the virus, and three monoclonal antibodies against the homodimers could neutralize HEV infectivity and/or immune-capture of the virus. Furthermore, homodimers of p239 further interact to form particles of 23 nm diameter, rendering it an efficacious candidate vaccine. In light of this we postulate that the interactions involved in the formation of the homodimers and particles might be similar to those involved in assembly of the virus capsid. Presently, mutational analysis was carried out to identify these sites of interactions. The site of dimeric interactions was located to a cluster of six hydrophobic amino acids residues, Ala(597), Val(598), Ala(599), Leu(601), and Ala(602); furthermore, the site involved in particle formation was located at amino acids 368-394. The possibility that these sites are also involved in assembly of the virus capsid is supported by the fact that they are located at two major and highly conserved hydrophobic regions of the HEV structural protein.