Morgunova Ekaterina, Yin Yimeng, Jolma Arttu, Dave Kashyap, Schmierer Bernhard, Popov Alexander, Eremina Nadejda, Nilsson Lennart, Taipale Jussi
Department of Biosciences and Nutrition, Karolinska Institutet, SE 141 83 Stockholm, Sweden.
European Synchrotron Radiation Facility, Division of Experiments, 38 000 Grenoble, France.
Nat Commun. 2015 Dec 3;6:10050. doi: 10.1038/ncomms10050.
The mammalian cell cycle is controlled by the E2F family of transcription factors. Typical E2Fs bind to DNA as heterodimers with the related dimerization partner (DP) proteins, whereas the atypical E2Fs, E2F7 and E2F8 contain two DNA-binding domains (DBDs) and act as repressors. To understand the mechanism of repression, we have resolved the structure of E2F8 in complex with DNA at atomic resolution. We find that the first and second DBDs of E2F8 resemble the DBDs of typical E2F and DP proteins, respectively. Using molecular dynamics simulations, biochemical affinity measurements and chromatin immunoprecipitation, we further show that both atypical and typical E2Fs bind to similar DNA sequences in vitro and in vivo. Our results represent the first crystal structure of an E2F protein with two DBDs, and reveal the mechanism by which atypical E2Fs can repress canonical E2F target genes and exert their negative influence on cell cycle progression.
哺乳动物细胞周期受转录因子E2F家族的调控。典型的E2F与相关二聚化伴侣（DP）蛋白以异源二聚体形式结合DNA，而非典型E2F，即E2F7和E2F8含有两个DNA结合结构域（DBD），并作为阻遏物发挥作用。为了解阻遏机制，我们以原子分辨率解析了E2F8与DNA复合物的结构。我们发现，E2F8的第一个和第二个DBD分别类似于典型E2F和DP蛋白的DBD。通过分子动力学模拟、生化亲和力测量和染色质免疫沉淀，我们进一步表明，非典型和典型E2F在体外和体内均与相似的DNA序列结合。我们的结果代表了具有两个DBD的E2F蛋白的首个晶体结构，并揭示了非典型E2F能够阻遏经典E2F靶基因并对细胞周期进程产生负面影响的机制。
