Roy A L, Du H, Gregor P D, Novina C D, Martinez E, Roeder R G
Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
EMBO J. 1997 Dec 1;16(23):7091-104. doi: 10.1093/emboj/16.23.7091.
The transcription factor TFII-I has been shown to bind independently to two distinct promoter elements, a pyrimidine-rich initiator (Inr) and a recognition site (E-box) for upstream stimulatory factor 1 (USF1), and to stimulate USF1 binding to both of these sites. Here we describe the isolation of a cDNA encoding TFII-I and demonstrate that the corresponding 120 kDa polypeptide, when expressed ectopically, is capable of binding to both Inr and E-box elements. The primary structure of TFII-I reveals novel features that include six directly repeated 90 residue motifs that each possess a potential helix-loop/span-helix homology. These unique structural features suggest that TFII-I may have the capacity for multiple protein-protein and, potentially, multiple protein-DNA interactions. Consistent with this hypothesis and with previous in vitro studies, we further demonstrate that ectopic TFII-I and USF1 can act synergistically, and in some cases independently, to activate transcription in vivo through both Inr and the E-box elements of the adenovirus major late promoter. We also describe domains of USF1 that are necessary for its independent and synergistic activation functions.
转录因子TFII-I已被证明可独立结合两个不同的启动子元件，一个富含嘧啶的起始子（Inr）和上游刺激因子1（USF1）的识别位点（E盒），并刺激USF1与这两个位点结合。在此，我们描述了编码TFII-I的cDNA的分离，并证明相应的120 kDa多肽在异位表达时能够结合Inr和E盒元件。TFII-I的一级结构揭示了新的特征，包括六个直接重复的90个残基基序，每个基序都具有潜在的螺旋-环/跨螺旋同源性。这些独特的结构特征表明TFII-I可能具有多种蛋白质-蛋白质相互作用以及潜在的多种蛋白质-DNA相互作用的能力。与该假设以及先前的体外研究一致，我们进一步证明异位表达的TFII-I和USF1可以协同作用，并且在某些情况下独立作用，通过腺病毒主要晚期启动子的Inr和E盒元件在体内激活转录。我们还描述了USF1独立和协同激活功能所必需的结构域。
