Kim Y H, Kang S K, Lee Y I
Molecular Genetics Laboratory, Genetic Engineering Research Institute, Taejon, Korea.
Biochem Biophys Res Commun. 1993 Dec 15;197(2):894-903. doi: 10.1006/bbrc.1993.2563.
X protein of hepatitis B virus (HBV-X) is a transactivator to a wide variety of viral and cellular transcriptional regulatory elements. Since HBV-X does not act on a common cis-regulatory element of a wide variety of regulatory elements nor does it bind to DNA directly, it has been proposed that HBV-X acts indirectly through protein-protein interactions with other transcription factors or signal transducing pathway. In order to determine the functional domain of HBV-X, we have constructed and analyzed a number of deletion and site specific mutants. Our results showed that leucine zipper-like sequences were found in the C-terminal region of HBV-X and were very important for its transactivating activity. In the analysis of deletion mutants, seven conserved and strong basic amino acids (amino acids 135-141) were essential for the transactivating activity of HBV-X.
乙型肝炎病毒（HBV-X）的X蛋白是一种对多种病毒和细胞转录调控元件起反式激活作用的蛋白。由于HBV-X既不作用于多种调控元件的共同顺式调控元件，也不直接与DNA结合，因此有人提出HBV-X通过与其他转录因子或信号转导途径的蛋白质-蛋白质相互作用间接发挥作用。为了确定HBV-X的功能结构域，我们构建并分析了许多缺失和位点特异性突变体。我们的结果表明，在HBV-X的C末端区域发现了类似亮氨酸拉链的序列，这些序列对其反式激活活性非常重要。在缺失突变体的分析中，七个保守且强碱性氨基酸（第135-141位氨基酸）对HBV-X的反式激活活性至关重要。
