Längst G, Blank T A, Becker P B, Grummt I
German Cancer Research Center, Division of Molecular Biology of the Cell II, Heidelberg, Germany.
EMBO J. 1997 Feb 17;16(4):760-8. doi: 10.1093/emboj/16.4.760.
Eukaryotic ribosomal gene promoters are preceded by a terminator element which is recognized by the transcription termination factor TTF-I. We have studied the function of this promoter-proximal terminator and show that binding of TTF-I is the key event which leads to ATP-dependent nucleosome remodeling and transcriptional activation of mouse rDNA pre-assembled into chromatin. We have analyzed TTF-I mutants for their ability to bind to free or nucleosomal DNA, and show that the DNA binding domain of TTF-I on its own is not sufficient for interaction with chromatin, indicating that specific protein features exist that endow a transcription factor with chromatin binding and remodeling properties. This first analysis of RNA polymerase I transcription in chromatin provides a clue for the function of the upstream terminator and establishes a dual role for TTF-I both as a termination factor and a chromatin-specific transcription activator.
真核生物核糖体基因启动子之前有一个终止子元件，该元件可被转录终止因子TTF-I识别。我们研究了这个启动子近端终止子的功能，结果表明TTF-I的结合是导致ATP依赖的核小体重塑以及转录激活预先组装成染色质的小鼠rDNA的关键事件。我们分析了TTF-I突变体与游离或核小体DNA结合的能力，结果表明TTF-I的DNA结合结构域自身不足以与染色质相互作用，这表明存在特定的蛋白质特征赋予转录因子染色质结合和重塑特性。对染色质中RNA聚合酶I转录的首次分析为上游终止子的功能提供了线索，并确立了TTF-I作为终止因子和染色质特异性转录激活因子的双重作用。
