Hisatake K, Roeder R G, Horikoshi M
Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021.
Nature. 1993 Jun 24;363(6431):744-7. doi: 10.1038/363744a0.
The protein TFIIB is a general transcription initiation factor that interacts with a promoter complex (D.DNA) containing the TATA-binding subunit (TFIID tau, or TBP) of TFIID to facilitate subsequent interaction with RNA polymerase II (ref. 2) through the associated TFIIF (ref. 3). The potential bridging function of TFIIB raises the possibility of two structural domains and emphasizes the importance of TFIIB structure-function studies for a further understanding of preinitiation complex assembly and function. Here we show that human TFIIB (refs 5,6) is comprised of functionally distinct N- and C-terminal domains. The C-terminal domain, containing the direct repeats and associated basic regions, is necessary and sufficient for interaction with the D.DNA complex. By contrast, the N-terminal domain that is dispensable for formation of the TFIID tau-TFIIB-promoter (D.B.DNA) complex is required for subsequent events leading to basal transcription initiation. On the basis of these results, we discuss structural and functional similarities between TFIIB and TFIID tau, which have similar structural organization and motifs.
蛋白质TFIIB是一种通用转录起始因子，它与包含TFIID的TATA结合亚基（TFIID τ，或TBP）的启动子复合物（D.DNA）相互作用，以促进随后通过相关的TFIIF与RNA聚合酶II相互作用（参考文献2）。TFIIB的潜在桥接功能增加了存在两个结构域的可能性，并强调了TFIIB结构功能研究对于进一步理解起始前复合物组装和功能的重要性。在这里，我们表明人类TFIIB（参考文献5、6）由功能不同的N端和C端结构域组成。包含直接重复序列和相关碱性区域的C端结构域对于与D.DNA复合物的相互作用是必要且充分的。相比之下，对于形成TFIID τ-TFIIB-启动子（D.B.DNA）复合物可有可无的N端结构域，对于导致基础转录起始的后续事件是必需的。基于这些结果，我们讨论了TFIIB和TFIID τ之间的结构和功能相似性，它们具有相似的结构组织和基序。
