THE ARGININE-RICH DOMAIN OF THE HEPATITIS-B VIRUS CORE PROTEIN IS REQUIRED FOR PREGENOME ENCAPSIDATION AND PRODUCTIVE VIRAL POSITIVE-STRAND DNA-SYNTHESIS BUT NOT FOR VIRUS ASSEMBLY
THE ARGININE-RICH DOMAIN OF THE HEPATITIS-B VIRUS CORE PROTEIN IS REQUIRED FOR PREGENOME ENCAPSIDATION AND PRODUCTIVE VIRAL POSITIVE-STRAND DNA-SYNTHESIS BUT NOT FOR VIRUS ASSEMBLY
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DOI：
10.1128/jvi.66.7.4107-4116.1992
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发表时间：
1992-07-01
影响因子：
5.4
通讯作者：
NASSAL, M
中科院分区：
文献类型：
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作者：
NASSAL, M
具有复制能力的B型肝炎病毒（HBV）核衣壳的组装需要核心蛋白、P蛋白和RNA前基因组的相互作用。核心蛋白含有一个富含精氨酸的C-末端结构域，其在异源表达系统中可用于颗粒形成。使用一系列C-末端截短的核心蛋白在HuH 7细胞中的瞬时表达，我研究了这个基本区域在完整HBV基因组背景下的功能作用。含有至少144个N-末端氨基酸的所有变体都是组装能力强的，但仅在由164个或更多个氨基酸组成的变体中观察到有效的前基因组重排。这些数据表明，富含精氨酸的区域的功能之一是提供核心蛋白和RNA前基因组之间的相互作用。然而，在以氨基酸164结尾的变体的核心中，完整正链DNA的产生急剧减少。此外，几乎所有的正链DNA起源于原位引发，而在野生型颗粒中，这种类型的引发不支持松弛环状DNA（RC-DNA）的形成占约一半的正链。进一步的C-末端残基的位置173恢复RC-DNA的形成，相应的变体没有不同的全长核心蛋白在所有使用的测定。观察到RNA的降解和RC-DNA的形成可以在遗传上分开，这表明核心蛋白通过其基本的C-末端区域也作为HBV复制中的必要辅助组分，可能像组蛋白或像单链DNA结合蛋白。与它们对HBV复制的重要性相反，超过氨基酸164的序列对于包膜病毒体的形成是不需要的。由于来自变体164的颗粒不含成熟DNA基因组，因此基因组成熟信号显然不是HBV核衣壳表达所必需的。
Assembly of replication-competent hepatitis B virus (HBV) nucleocapsids requires the interaction of the core protein, the P protein, and the RNA pregenome. The core protein contains an arginine-rich C-terminal domain which is dispensable for particle formation in heterologous expression systems. Using transient expression in HuH7 cells of a series of C-terminally truncated core proteins, I examined the functional role of this basic region in the context of a complete HBV genome. All variants containing at least the 144 N-terminal amino acids were assembly competent, but efficient pregenome encapsidation was observed only with variants consisting of 164 or more amino acids. These data indicate that one function of the arginine-rich region is to provide the interactions between core protein and RNA pregenome. However, in cores from the variant ending with amino acid 164, the production of complete positive-strand DNA was drastically reduced. Moreover, almost all positive-strand DNA originated from in situ priming, whereas in wild-type particles, this type of priming not supporting the formation of relaxed circular DNA (RC-DNA) accounted for about one half of the positive strands. Further C-terminal residues to position 173 restored RC-DNA formation, and the corresponding variant did not differ from the full-length core protein in all assays used. The observation that RNA encapsidation and formation of RC-DNA can be genetically separated suggests that the core protein, via its basic C-terminal region, also acts as an essential auxiliary component in HBV replication, possibly like a histone, or like a single-stranded-DNA-binding protein. In contrast to their importance for HBV replication, sequences beyond amino acid 164 were not required for the formation of enveloped virions. Since particles from variant 164 did not contain mature DNA genomes, a genome maturation signal is apparently not required for HBV nucleocapsid envelopment.