Schröder Oliver, Bryant Gene O, Geiduschek E Peter, Berk Arnold J, Kassavetis George A
Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0634, USA.
EMBO J. 2003 Oct 1;22(19):5115-24. doi: 10.1093/emboj/cdg476.
The TATA-binding protein (TBP) is involved in all nuclear transcription. We show that a common site on TBP is used for transcription initiation complex formation by RNA polymerases (pols) II and III. TBP, the transcription factor IIB (TFIIB)-related factor Brf1 and the pol III-specific factor Bdp1 constitute TFIIIB. A photochemical cross-linking approach was used to survey a collection of human TBP surface residue mutants for their ability to form TFIIIB-DNA complexes reliant on only the TFIIB-related part of Brf1. Mutations impairing complex formation and transcription were identified and mapped on the surface of TBP. The most severe effects were observed for mutations in the C-terminal stirrup of TBP, which is the principal site of interaction between TBP and TFIIB. Structural modeling of the Brf1-TBP complex and comparison with its TFIIB-TBP analog further rationalizes the close resemblance of the TBP interaction with the N-proximal part of Brf1 and TFIIB, and establishes the conserved usage of a TBP surface in pol II and pol III transcription for a conserved function in the initiation of transcription.
TATA 结合蛋白（TBP）参与所有的核转录过程。我们发现 TBP 上的一个共同位点被 RNA 聚合酶（pols）II 和 III 用于转录起始复合物的形成。TBP、转录因子 IIB（TFIIB）相关因子 Brf1 和 pol III 特异性因子 Bdp1 构成 TFIIIB。采用光化学交联方法，对一组人类 TBP 表面残基突变体进行检测，以评估它们仅依赖 Brf1 的 TFIIB 相关部分形成 TFIIIB-DNA 复合物的能力。确定了损害复合物形成和转录的突变，并将其定位在 TBP 表面。在 TBP 的 C 端马镫区域的突变观察到了最严重的影响，该区域是 TBP 与 TFIIB 相互作用的主要位点。Brf1-TBP 复合物的结构建模及其与 TFIIB-TBP 类似物的比较进一步解释了 TBP 与 Brf1 和 TFIIB 的 N 近端部分相互作用的密切相似性，并确立了在 pol II 和 pol III 转录中 TBP 表面在转录起始中的保守功能的保守用法。
