African swine fever virus polyproteins pp220 and pp62 assemble into the core shell
African swine fever virus polyproteins pp220 and pp62 assemble into the core shell
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DOI：
10.1128/jvi.76.24.12473-12482.2002
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发表时间：
2002-12-01
影响因子：
5.4
通讯作者：
Salas, ML
中科院分区：
文献类型：
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作者：
Andrés, G;Alejo, A;Salas, ML
非洲猪瘟病毒（ASFV）是一种复杂的有包膜的DNA病毒，它表达两种多聚蛋白前体，pp220和pp62，经过蛋白水解加工后产生病毒粒子的几种主要成分。我们已经分析了多聚蛋白pp62（成熟产物p35和p15的前体形式）在病毒形态发生中的结构作用。对纯化的病毒粒子进行一维和二维凝胶的光密度分析表明，蛋白质p35和p15以及pp220衍生的产物在病毒粒子中以等分子数量存在。免疫电子显微镜显示，pp62衍生的产物定位在核心壳上，这是一个位于含DNA的拟核和内膜之间的基质样区域，pp220衍生的产物也定位在此处。脉冲追踪实验表明，两种多聚蛋白前体的加工与病毒组装同时进行。此外，利用可诱导的ASFV重组体，我们表明pp62的加工需要pp220核心前体的表达，而pp220和pp62这两种前体的加工都依赖于主要衣壳蛋白p72的表达。有趣的是，当p72的表达受阻时，未加工的pp220和pp62多聚蛋白会组装成异常的拉链状元件，由一种细长的膜结合蛋白结构组成，让人联想到核心壳。而且，这两种多聚蛋白在COS细胞中共表达时会相互作用形成拉链状结构。总之，这些发现表明，来自这两种多聚蛋白的成熟产物（它们总共约占病毒粒子蛋白质质量的30%）是核心壳的基本成分，并且多聚蛋白加工代表了一个与ASFV形态发生相关的成熟过程。
African swine fever virus (ASFV), a complex enveloped DNA virus, expresses two polyprotein precursors, pp220 and pp62, which after proteolytic processing give rise to several major components of the virus particle. We have analyzed the structural role of polyprotein pp62, the precursor form of mature products p35 and p15, in virus morphogenesis. Densitometric analysis of one- and two-dimensional gels of purified virions showed that proteins p35 and p15, as well as the pp220-derived products, are present in equimolecular amounts in the virus particle. Immunoelectron microscopy revealed that the pp62-derived products localize at the core shell, a matrix-like domain placed between the DNA-containing nucleoid and the inner envelope, where the pp220-derived products are also localized. Pulse-chase experiments indicated that the processing of both polyprotein precursors is concomitant with virus assembly. Furthermore, using inducible ASFV recombinants, we show that pp62 processing requires the expression of the pp220 core precursor, whereas the processing of both precursors pp220 and pp62 is dependent on expression of the major capsid protein p72. Interestingly, when p72 expression is blocked, unprocessed pp220 and pp62 polyproteins assemble into aberrant zipper-like elements consisting of an elongated membrane-bound protein structure reminiscent of the core shell. Moreover, the two polyproteins, when coexpressed in COS cells, interact with each other to form zipper-like structures. Together, these findings indicate that the mature products derived from both polyproteins, which collectively account for about 30% of the virion protein mass, are the basic components of the core shell and that polyprotein processing represents a maturational process related to ASFV morphogenesis.