Subramanian T, D'Sa-Eipper C, Elangovan B, Chinnadurai G
Institute for Molecular Virology, St Louis University Medical Center, MO 63110.
Nucleic Acids Res. 1994 Apr 25;22(8):1496-9. doi: 10.1093/nar/22.8.1496.
The N-terminal 48 amino acids of the Tat protein of human immunodeficiency virus type (HIV)-1 constitute its activation region. This region can autonomously activate transcription when targeted to the HIV-1 long terminal repeat or certain heterologous promoters either through DNA binding sites located upstream of the transcription initiation site or via downstream RNA binding sites in mammalian cells. To determine whether the Tat activation region can function in yeast, we have assayed the effect of a chimeric gene (GAL-Tat48) expressing the DNA binding domain of the yeast transcription factor Gal4 (residues 1-147) and the activation region of Tat on GAL1 promoter-directed expression of the lacZ reporter gene in Saccharomyces cerevisiae. Our results indicate that the Gal-Tat48 fusion protein can induce significant activation of the GAL1 promoter. Analysis of a number of Tat mutants located within the activation region indicate that the amino acid residues of Tat essential for trans-activation in mammalian cells are also required for transactivation in yeast. Our results suggest that Tat-mediated transcriptional activation may involve a mechanism conserved among yeast and mammalian cells.
人类免疫缺陷病毒1型（HIV-1）Tat蛋白的N端48个氨基酸构成其激活区域。当该区域通过位于转录起始位点上游的DNA结合位点或哺乳动物细胞中的下游RNA结合位点靶向HIV-1长末端重复序列或某些异源启动子时，它能够自主激活转录。为了确定Tat激活区域在酵母中是否起作用，我们检测了一个嵌合基因（GAL-Tat48）的作用，该基因表达酵母转录因子Gal4的DNA结合结构域（第1至147位氨基酸残基）以及Tat的激活区域，用于在酿酒酵母中指导lacZ报告基因的GAL1启动子表达。我们的结果表明，Gal-Tat48融合蛋白能够显著诱导GAL1启动子的激活。对位于激活区域内的多个Tat突变体的分析表明，Tat在哺乳动物细胞中反式激活所必需的氨基酸残基在酵母中反式激活时也是必需的。我们的结果表明，Tat介导的转录激活可能涉及酵母和哺乳动物细胞中保守的机制。
