O'Connor R J, Hearing P
Department of Microbiology, State University of New York, Stony Brook 11794-8621.
Nucleic Acids Res. 1991 Dec 11;19(23):6579-86. doi: 10.1093/nar/19.23.6579.
E2F is a cellular transcription factor that binds to the adenovirus (Ad) E1A enhancer and E2aE promoter regions, to the cellular c-myc P2 and dihydrofolate reductase promoters, and to other viral and cellular regulatory regions. The binding activity of E2F to the Ad E2aE promoter is dramatically increased during an adenovirus infection (termed E2F induction). E2F induction is dependent on the expression of the 150 amino acid E4-ORF6/7 protein which forms a direct, physical complex with E2F to mediate the cooperative and stable binding of E2F to inverted sites in the E2aE promoter. Using in vitro DNA binding assays to measure the formation of the infection-specific complexes, we have defined the minimal domain of the E4-ORF6/7 protein, the C-terminal 70 amino acids, required to complex with E2F and stabilize its binding at the E2aE promoter. The ability of mutant E4-ORF6/7 proteins to form the stable E2F-E2aE promoter complex in vitro correlated well with their ability to trans-activate E2 transcription in vivo. These observations support a model in which the E4-ORF6/7 protein binds to E2F to induce the cooperative binding of two E2F molecules to the E2aE promoter thereby activating E2 transcription.
E2F是一种细胞转录因子，它能与腺病毒（Ad）E1A增强子和E2aE启动子区域、细胞c-myc P2和二氢叶酸还原酶启动子以及其他病毒和细胞调控区域结合。在腺病毒感染期间，E2F与Ad E2aE启动子的结合活性显著增加（称为E2F诱导）。E2F诱导依赖于150个氨基酸的E4-ORF6/7蛋白的表达，该蛋白与E2F形成直接的物理复合物，以介导E2F与E2aE启动子中反向位点的协同和稳定结合。使用体外DNA结合试验来测量感染特异性复合物的形成，我们已经确定了E4-ORF6/7蛋白的最小结构域，即C末端的70个氨基酸，它是与E2F结合并稳定其在E2aE启动子上结合所必需的。突变的E4-ORF6/7蛋白在体外形成稳定的E2F-E2aE启动子复合物的能力与其在体内反式激活E2转录的能力密切相关。这些观察结果支持了一个模型，即E4-ORF6/7蛋白与E2F结合，诱导两个E2F分子与E2aE启动子协同结合，从而激活E2转录。
