TFII-I regulates Vβ promoter activity through an initiator element
TFII-I regulates Vβ promoter activity through an initiator element
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DOI：
10.1128/mcb.18.8.4444
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发表时间：
1998-08-01
影响因子：
5.3
通讯作者：
Roy, AL
中科院分区：
文献类型：
--
作者：
Cheriyath, V;Novina, CD;Roy, AL
在我们努力了解自然发生的TATA-less但含有启动子（Inr）的基因的转录调控时，我们采用了小鼠t细胞受体V β 5.2启动子作为模型。在这里，我们通过瞬时转染实验证明，Inr结合转录因子TFII-I是V β启动子在体内有效表达所必需的。Inr元件的突变减少了TFII-I的结合，也通过异位TFII-I消除了V β启动子的活性。我们进一步生化鉴定了TFII-I， p70的蛋白酶抗性n端DNA结合片段。当异位表达时，重组p70与V β Inr元件结合，其特异性与野生型TFII-I相似。更重要的是，缺乏独立激活功能的p70作为显性负突变体，抑制野生型TFII-I的inr特异性功能。然而，当融合到酵母激活蛋白GAL4的异源激活主体时，p70的激活功能得以恢复。综上所述，这些数据表明TFII-I在体内的功能需要一个完整的Inr元件，而TFII-I的Inr特异性转录功能仅由其n端DNA结合域决定，而不需要其自身的c端激活域。
In our effort to understand the transcriptional regulation of naturally occurring TATA-less but initiator (Inr)-containing genes, we have employed the murine T-cell receptor V beta 5.2 promoter as a model. Here we show by transient-transfection assays that the Inr binding transcription factor TFII-I is required for efficient expression of the V beta promoter in vivo. Mutations in the Inr element that reduced binding of TFII-I also abolished the V beta promoter activity by ectopic TFII-I. We further biochemically identified a protease-resistant N-terminal DNA binding fragment of TFII-I, p70. When ectopically expressed, recombinant p70 bound to the V beta Inr element with a specificity similar to that of wild-type TFII-I. More importantly, p70, which lacks independent activation functions, behaved as a dominant negative mutant that inhibited Inr-specific function of wild-type TFII-I. However, the activation functions of p70 were restored when fused to the heterologous activation do main of the yeast activator protein GAL4. Taken together, these data suggest that TFII-I functions in vivo require an intact Inr element and that the Inr-specific transcriptional functions of TFII-I are solely dictated by its N-terminal DNA binding domain and do not require its own C-terminal activation domain.