Hahn S, Buratowski S, Sharp P A, Guarente L
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
EMBO J. 1989 Nov;8(11):3379-82. doi: 10.1002/j.1460-2075.1989.tb08501.x.
The yeast homolog of the mammalian RNA polymerase II general transcription factor TFIIA has been identified by complementation of a mammalian in vitro transcription system depleted for TFIIA. Like the mammalian factor, the yeast protein does not bind DNA, alters the size of the TFIID DNase I footprint at the adenovirus major late promoter, and forms specific TFIIA-TFIID-DNA complexes which are stable during electrophoresis in native acrylamide gels. The partially purified yeast factor was used to investigate its effect on the binding of TFIID to the major late promoter. Contrary to earlier models, we find that TFIIA does not significantly change the affinity or kinetics of TFIID binding, suggesting that it acts by altering the conformation of TFIID and/or by serving as a bridge between TFIID and the other general transcription factors.
通过对缺乏TFIIA的哺乳动物体外转录系统进行互补，已鉴定出哺乳动物RNA聚合酶II通用转录因子TFIIA的酵母同源物。与哺乳动物因子一样，酵母蛋白不结合DNA，可改变腺病毒主要晚期启动子处TFIID的DNA酶I足迹大小，并形成特定的TFIIA-TFIID-DNA复合物，该复合物在天然丙烯酰胺凝胶电泳过程中是稳定的。利用部分纯化的酵母因子来研究其对TFIID与主要晚期启动子结合的影响。与早期模型相反，我们发现TFIIA不会显著改变TFIID结合的亲和力或动力学，这表明它通过改变TFIID的构象和/或作为TFIID与其他通用转录因子之间的桥梁来发挥作用。
