Robert F, Douziech M, Forget D, Egly J M, Greenblatt J, Burton Z F, Coulombe B
Departement de biologie, Faculté des sciences, Université de Sherbrooke, Québec, Canada.
Mol Cell. 1998 Sep;2(3):341-51. doi: 10.1016/s1097-2765(00)80278-6.
The formation of the RNA polymerase II (Pol II) initiation complex was analyzed using site-specific protein-DNA photo-cross-linking. We show that the RAP74 subunit of transcription factor (TF) IIF, through its RAP30-binding domain and an adjacent region necessary for the formation of homomeric interactions in vitro, dramatically alters the distribution of RAP30, TFIIE, and Pol II along promoter DNA between positions -40 and +26. This isomerization of the complex, which requires both TFIIF and TFIIE, is accompanied by tight wrapping of the promoter DNA for almost a full turn around Pol II. Addition of TFIIH enhances photo-cross-linking of Pol II to a number of promoter positions, suggesting that TFIIH tightens the DNA wrap around the enzyme. We present a general model to describe transcription initiation.
利用位点特异性蛋白质-DNA光交联分析了RNA聚合酶II(Pol II)起始复合物的形成。我们发现,转录因子(TF)IIF的RAP74亚基通过其RAP30结合结构域以及体外形成同源相互作用所必需的相邻区域,显著改变了RAP30、TFIIE和Pol II在启动子DNA上-40至+26位之间的分布。这种复合物的异构化需要TFIIF和TFIIE两者参与,同时伴随着启动子DNA围绕Pol II紧密缠绕近一整圈。添加TFIIH增强了Pol II与多个启动子位置的光交联,表明TFIIH收紧了酶周围的DNA缠绕。我们提出了一个描述转录起始的通用模型。