Tan Juan, Qiao Wentao, Xu Fengwen, Han Hongqi, Chen Qimin, Geng Yunqi
Key Laboratory of Molecular Microbiology and Biotechnology (Ministry of Education) and Key Laboratory of Microbial Functional Genomics (Tianjin), College of Life Sciences, Nankai University, Tianjin 300071, China.
Virology. 2008 Jun 20;376(1):236-41. doi: 10.1016/j.virol.2008.03.029. Epub 2008 Apr 29.
The BTas protein of bovine foamy virus (BFV) is a 249-amino-acid nuclear regulatory protein which transactivates viral gene expression directed by the long terminal repeat promoter (LTR) and the internal promoter (IP). Here, we demonstrate the BTas protein forms a dimeric complex in mammalian cells by using mammalian two hybrid systems and cross-linking assay. Functional analyses with deletion mutants reveal that the region of 46-62aa is essential for dimer formation. Furthermore, our results show that deleting the dimerization region of BTas did not affect the localization of BTas, but that it did result in the loss of its transactivational activity on the LTR and IP. Furthermore, BTas (Delta46-62aa) retained binding ability to the LTR and IP similar to that of the wild-type BTas. These data suggest the dimerization region is necessary for the transactivational function of BTas and is crucial to the replication of BFV.
牛泡沫病毒（BFV）的BTas蛋白是一种由249个氨基酸组成的核调节蛋白，它可反式激活由长末端重复启动子（LTR）和内部启动子（IP）指导的病毒基因表达。在此，我们通过使用哺乳动物双杂交系统和交联试验证明BTas蛋白在哺乳动物细胞中形成二聚体复合物。对缺失突变体的功能分析表明，46 - 62氨基酸区域对于二聚体形成至关重要。此外，我们的结果表明，缺失BTas的二聚化区域并不影响BTas的定位，但确实导致其对LTR和IP的反式激活活性丧失。此外，BTas（Delta46 - 62aa）保留了与野生型BTas相似的与LTR和IP的结合能力。这些数据表明二聚化区域对于BTas的反式激活功能是必需的，并且对BFV的复制至关重要。
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