Lin Y S, Ha I, Maldonado E, Reinberg D, Green M R
Program in Molecular Medicine, University of Massachusetts Medical Center, Worcester 01605.
Nature. 1991 Oct 10;353(6344):569-71. doi: 10.1038/353569a0.
A central issue in eukaryotic transcriptional regulation is the mechanism by which promoter-specific transcription factors (activators) stimulate transcription. Two lines of evidence indicate that the general transcription factor TFIIB is a pivotal component in the mechanism by which an acidic activator functions. First, during assembly of the preinitiation complex TFIIB binding is a rate-limiting step enhanced by an acidic activator. Second, the TFIIB activity in a HeLa cell nuclear extract is specifically retained on a column containing an acidic activating region. But because our previous study monitored only TFIIB activity, it remains possible that the interaction between TFIIB and the acidic activating region is mediated through additional proteins, for example, those designated as adaptors, coactivators or mediators. A complementary clone encoding TFIIB has recently been isolated and shown to encode a polypeptide of relative molecular mass 35,000. Here we report that TFIIB expressed in and purified from Escherichia coli (recombinant TFIIB) binds directly to the potent acidic activating region of the herpes simplex virus-1 VP16 protein.
真核生物转录调控中的一个核心问题是启动子特异性转录因子（激活因子）刺激转录的机制。有两条证据表明，通用转录因子TFIIB是酸性激活因子发挥作用机制中的关键组成部分。第一，在起始前复合物组装过程中，TFIIB的结合是一个限速步骤，酸性激活因子可增强此步骤。第二，HeLa细胞核提取物中的TFIIB活性特异性地保留在含有酸性激活区域的柱上。但由于我们之前的研究仅监测了TFIIB活性，TFIIB与酸性激活区域之间的相互作用仍有可能是通过其他蛋白质介导的，例如那些被称为衔接蛋白、共激活因子或中介物的蛋白质。最近分离出了一个编码TFIIB的互补克隆，显示其编码一种相对分子质量为35,000的多肽。在此我们报告，在大肠杆菌中表达并纯化的TFIIB（重组TFIIB）直接与单纯疱疹病毒1型VP16蛋白的强效酸性激活区域结合。
