Kamine J, Chinnadurai G
Institute for Molecular Virology, St. Louis University School of Medicine, Missouri 63110.
J Virol. 1992 Jun;66(6):3932-6. doi: 10.1128/JVI.66.6.3932-3936.1992.
We have previously shown that the human immunodeficiency virus type 1 (HIV-1) Tat protein can activate a synthetic promoter containing consensus-binding sites for the cellular transcription factor Sp1. In this report, we show that a GAL-Tat fusion protein targeted via GAL4 DNA-binding sites can also trans activate an HIV-1 LTR promoter independently of the trans-activation response region. To show that the trans activation of the promoter by Tat directly involves the Sp1 protein, we have targeted a GAL-Sp1 fusion protein to the long terminal repeat promoter via upstream GAL4-binding sites. In the presence of Tat and GAL-Sp1, the promoter is synergistically trans activated at the transcriptional level, indicating that Tat and Sp1 functionally interact to trans activate the HIV-1 promoter. The Sp1 synergism is relatively specific, since another chimeric transcriptional activator, GAL-VP16, does not appear to be significantly synergistic with Tat.
我们之前已经表明，人类免疫缺陷病毒1型（HIV-1）的Tat蛋白可以激活一个含有细胞转录因子Sp1共有结合位点的合成启动子。在本报告中，我们表明通过GAL4 DNA结合位点靶向的GAL-Tat融合蛋白也可以独立于反式激活反应区域反式激活HIV-1 LTR启动子。为了证明Tat对启动子的反式激活直接涉及Sp1蛋白，我们通过上游GAL4结合位点将GAL-Sp1融合蛋白靶向到长末端重复启动子。在Tat和GAL-Sp1存在的情况下，启动子在转录水平上被协同反式激活，表明Tat和Sp1在功能上相互作用以反式激活HIV-1启动子。Sp1的协同作用相对具有特异性，因为另一种嵌合转录激活因子GAL-VP16似乎与Tat没有明显的协同作用。
