Assembly of a functional beta interferon enhanceosome is dependent on ATF-2-c-jun heterodimer orientation
Assembly of a functional beta interferon enhanceosome is dependent on ATF-2-c-jun heterodimer orientation
复制标题
DOI：
10.1128/mcb.20.13.4814-4825.2000
复制
发表时间：
2000-07-01
影响因子：
5.3
通讯作者：
Maniatis, T
中科院分区：
文献类型：
--
作者：
Falvo, JV;Parekh, BS;Maniatis, T
异二聚体转录因子，包括碱性区-亮氨酸拉链（bZIP）蛋白ATF-2-c-jun，是介导病毒诱导人β干扰素（IFN-β）基因的增强体的充分表征的组分。在这里，我们报告说，在IFN-β增强体内的ATF-2-c-jun异二聚体结合在一个特定的方向，这是所需的组装ATF-2-c-jun和干扰素调节因子3（IRF-3）之间的复合物。我们证明，正确的方向的ATF-2-c-jun结合位点是必需的IFN-β基因的病毒诱导和IRF-3依赖性激活的复合ATF-2-c-jun-IRF网站在IFN-β启动子。我们还表明，在体外的DNA结合的ATP-2-c-jun异源二聚体采用固定的方向后，IRF-3在IFN-β增强子中的相邻位点的结合，并且IRF-3的DNA结合结构域足以介导这种效果。此外，我们表明ATF-2的DNA结合结构域是必要的，足以选择性的蛋白质-蛋白质相互作用与IRF-3。引人注目的是，用IFN-β报告基因构建体进行的体内染色质免疫沉淀实验揭示，在病毒感染后，IRF-3向IFN-β启动子的募集依赖于ATP-2-c-jun异二聚体结合位点的方向。这些观察结果表明bZIP和IRF转录因子家族之间的功能和物理协同性，并说明异二聚体转录因子在IFN-β增强体形成中的关键作用。
Heterodimeric transcription factors, including the basic region-leucine zipper (bZIP) protein ATF-2-c-jun, are well-characterized components of an enhanceosome that mediates virus induction of the human beta interferon (IFN-beta) gene. Here we report that within the IFN-beta enhanceosome the ATF-2-c-jun heterodimer binds in a specific orientation, which is required for assembly of a complex between ATF-2-c-jun and interferon regulatory factor 3 (IRF-3). We demonstrate that correct orientation of the ATF-2-c-jun binding site is required for virus induction of the IFN-beta gene and for IRF-3-dependent activation of a composite ATF-2-c-jun-IRF site in the IFN-beta promoter. We also show that in vitro the DNA-bound ATP-2-c-jun heterodimer adopts a fixed orientation upon the binding of IRF-3 at an adjacent site in the IFN-beta enhancer and that the DNA-binding domain of IRF-3 is sufficient to mediate this effect. In addition, we show that the DNA-binding domain of ATF-2 is necessary and sufficient for selective protein-protein interactions with IRF-3. Strikingly, in vivo chromatin immunoprecipitation experiments with IFN-beta reporter constructs reveal that recruitment of IRF-3 to the IFN-beta promoter upon virus infection is dependent on the orientation of the ATP-2-c-jun heterodimer binding site. These observations demonstrate functional and physical cooperativity between the bZIP and IRF transcription factor families and illustrate the critical role of heterodimeric transcription factors in formation of the IFN-beta enhanceosome.