EFFECT OF X-PROTEIN ON TRANSACTIVATION OF HEPATITIS-B VIRUS PROMOTERS AND ON VIRAL REPLICATION
EFFECT OF X-PROTEIN ON TRANSACTIVATION OF HEPATITIS-B VIRUS PROMOTERS AND ON VIRAL REPLICATION
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DOI：
10.1006/viro.1993.1381
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发表时间：
1993-08-01
期刊：
影响因子：
3.7
通讯作者：
KOSHY, R
中科院分区：
文献类型：
--
作者：
NAKATAKE, H;CHISAKA, O;KOSHY, R
B型肝炎病毒（HBV）的X基因产物反式激活多种启动子，包括HBV基因组上的四种启动子（Rossner，1992，J.Med.Virol.36，101-117）。我们比较了它们的反式激活效率，并研究了启动子相对于其他作用元件的空间组织是否会影响它们的活性。设计了8个含有细菌氯霉素乙酰转移酶（CAT）基因的报告质粒构建体，其中4个具有与CAT基因连接的分离的HBV启动子。在其他四个中，CAT基因被插入到HBV基因组中保留的四个启动子的下游。用这些报告基因中的每一种与允许X蛋白表达的效应子质粒pRSVX一起转染人肝母细胞瘤系HepG 2的细胞。所有这些启动子都可以被X蛋白刺激约2至3.5倍，而不管它们在HBV基因组中的空间背景。对X基因中符合读框的ATG密码子的突变分析提供了反式激活因子产物由翻译的内部起始产生的证据。HBV基因组携带终止突变的X基因在密码子118处转染HepG 2细胞导致所有病毒组分的生产不良。它们的合成在野生型X基因转染后恢复。
The X gene product of hepatitis B virus (HBV) transactivates a wide variety of promoters, including four promoters on the HBV genome (Rossner, 1992,J. Med. Virol.36, 101-117). We compared their transactivation efficiencies and investigated whether the spatial organization of the promoters with respect to othercis-acting elements might influence their activities. Eight reporter plasmid constructs containing the bacterial chloramphenicol acetyltransferase (CAT) gene were designed such that four had the isolated HBV promoters linked to the CAT gene. In the other four, the CAT gene was inserted downstream to each of the four promoters retained in context in the HBV genome. Cells of the human hepatoblastoma line HepG2 were transfected with each one of these reporters together with an effector plasmid, pRSVX, which allowed expression of X protein. All of these promoters could be stimulated by X protein by approximately 2- to 3.5-fold irrespective of their spatial context in the HBV genome. Mutational analysis of in-frame ATG codons in the X gene provides evidence that transactivator product(s) are produced by internal initiation of translation. Transfection of HepG2 cells with HBV genomes bearing a stop mutation in the X gene at codon 118 resulted in poor production of all viral components. Their syntheses were restored upon transfection of the wild-type X gene.