Interactions of a DNA-bound transcriptional activator with the TBP-TFIIA-TFIIB-promoter quaternary complex
Interactions of a DNA-bound transcriptional activator with the TBP-TFIIA-TFIIB-promoter quaternary complex
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DOI：
10.1074/jbc.m211938200
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发表时间：
2003-03-28
影响因子：
4.8
通讯作者：
Coulombe, B
中科院分区：
文献类型：
--
作者：
Dion, V;Coulombe, B
位点特异性蛋白质-DNA 光交联表明，当与 TATA 元件上游不同距离处的同源位点结合时，嵌合转录激活剂 GAL4-VP16 可以与组装在 TATA 元件上的 TATA 盒结合蛋白 (TBP)-转录因子 IIA (TFIIA)-TFIIB 复合物发生物理相互作用。该结果表明启动子 DNA 的 DNA 弯曲和成环是 GAL4-VP16 与 TBP-TFIIA-TFIIB 复合物界面之间物理相互作用的结果。启动子 DNA 上的这种蛋白质-蛋白质相互作用至少需要存在一个 GAL4 结合位点，并在 TATA 元件上形成包含 TBP、TFIB 和 TFIIA 的四元复合物。值得注意的是，TBP-TFIIA-TFIIB-启动子复合物的拓扑结构不会因与 DNA 结合激活剂的相互作用而发生显着改变。我们还表明，GAL4-VP16 通过单个 GAL4 结合位点激活转录的能力根据其相对于 TATA 元件的精确位置和方向而变化，并且它可以接近通过多个结合位点获得的效率。综上所述，我们的结果表明，DNA 结合激活结构域的空间定位对于有效激活非常重要，这可能是通过最大化其与转录机制（包括 TBP-TFIIA-TFIIB-启动子四元复合物）的相互作用来实现的。
Site-specific protein-DNA photo-cross-linking was used to show that, when bound to its cognate site at various distances upstream of the TATA element, the chimeric transcriptional activator GAL4-VP16 can physically interact with a TATA box-binding protein (TBP)-transcription factor IIA (TFIIA)-TFIIB complex assembled on the TATA element. This result implies DNA bending and looping of promoter DNA as a result of the physical interaction between GAL4-VP16 and an interface of the TBP-TFIIA-TFIIB complex. This protein-protein interaction on promoter DNA minimally requires the presence of one GAL4 binding site and the formation of a quaternary complex containing TBP, TFIIB, and TFIIA on the TATA element. Notably, the topology of the TBP-TFIIA-TFIIB-promoter complex is not altered Significantly by the interaction with DNA-bound activators. We also show that the ability of GAL4-VP16 to activate transcription through a single GAL4 binding site varies according to its precise location and orientation relative to the TATA element and that it can approach the efficiency obtained with multiple binding sites. Taken together, our results indicate that the spatial positioning of the DNA-bound activation domain is important for efficient activation, possibly by maximizing its interactions with the transcriptional machinery including the TBP-TFIIA-TFIIB-promoter quaternary complex.