Kim T K, Roeder R G
Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021.
Proc Natl Acad Sci U S A. 1994 May 10;91(10):4170-4. doi: 10.1073/pnas.91.10.4170.
Activators can stimulate transcription through direct or indirect interactions with general initiation factors. We show here that the proline-rich activation domain of CTF1 (CCAAT-box-binding transcription factor 1) selectively interacts with TFIIB but not with the TATA-binding protein (TBP), whereas previous studies have shown that the acidic activation domain of viral VP16 interacts directly with both TBP and TFIIB. In addition, consistent with studies of acidic activation domains, we demonstrate that the activation domain of CTF1 facilitates the recruitment (or stabilization) of TFIIB within TBP-DNA complexes during preinitiation complex assembly. CTF1-enhanced TFIIB recruitment was observed in both human and yeast systems. The results indicate that the proline-rich activation domain enhances transcription, at least in part, through direct interactions with TFIIB and, with previous observations, suggest models involving either quantitative or qualitative changes in TFIIB-TFIID-promoter interactions that lead to increased utilization of downstream initiation factors.
激活因子可通过与通用起始因子的直接或间接相互作用来刺激转录。我们在此表明，CTF1（CCAAT盒结合转录因子1）富含脯氨酸的激活结构域选择性地与TFIIB相互作用，而不与TATA结合蛋白（TBP）相互作用，而先前的研究表明病毒VP16的酸性激活结构域与TBP和TFIIB都直接相互作用。此外，与对酸性激活结构域的研究一致，我们证明CTF1的激活结构域在起始前复合物组装过程中促进TFIIB在TBP-DNA复合物中的募集（或稳定）。在人和酵母系统中均观察到CTF1增强的TFIIB募集。结果表明，富含脯氨酸的激活结构域至少部分地通过与TFIIB的直接相互作用来增强转录，并且与先前的观察结果一起，提出了涉及TFIIB-TFIID-启动子相互作用的定量或定性变化的模型，这些变化导致下游起始因子的利用率增加。
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