Structural basis for subversion of cellular control mechanisms by the adenoviral E1A oncoprotein
Structural basis for subversion of cellular control mechanisms by the adenoviral E1A oncoprotein
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DOI：
10.1073/pnas.0906770106
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发表时间：
2009-08-11
影响因子：
11.1
通讯作者：
Wright, Peter E.
中科院分区：
文献类型：
--
作者：
Ferreon, Josephine C.;Martinez-Yamout, Maria A.;Wright, Peter E.
腺病毒早期区1A（E1 A）癌蛋白通过解除宿主细胞过程的调节并通过募集细胞蛋白（包括环AMP反应元件结合（CREB）结合蛋白（CBP）/p300和视网膜母细胞瘤蛋白（pRb））激活病毒基因表达来介导细胞转化。虽然E1 A能够独立地与CBP/p300或pRb相互作用，但同时结合两种蛋白质是最大生物活性所必需的。为了深入了解E1 A通过与必需的转录因子竞争结合CBP/p300来劫持细胞转录机器的机制，我们已经确定了CBP的转录衔接子锌指-2（TAZ 2）结构域和E1 A的保守区-1（CR 1）结构域之间的复合物的结构。E1 A CR 1结构域在游离状态下是非结构化的，并且在结合时折叠成由广泛的分子间疏水接触网络介导的局部螺旋结构。通过NMR滴定，我们表明，E1 A有效地竞争与N-末端的p53的反式激活结构域结合TAZ 2和pRb相互作用与E1 A在2个独立的网站位于CR 1和CR2。我们发现，pRb和CBP TAZ 2结构域可以同时结合到E1 A的CR 1位点，形成三元复合物，并提出了一个结构模型的pRb：E1 A：CBP复合物的基础上公布的同源二元复合物的X-射线数据。这些观察结果揭示了E1 A抑制p53介导的转录激活的分子基础，并为腺病毒E1 A癌蛋白的细胞转化效率提供了理论基础。
The adenovirus early region 1A (E1A) oncoprotein mediates cell transformation by deregulating host cellular processes and activating viral gene expression by recruitment of cellular proteins that include cyclic-AMP response element binding (CREB) binding protein (CBP)/p300 and the retinoblastoma protein (pRb). While E1A is capable of independent interaction with CBP/p300 or pRb, simultaneous binding of both proteins is required for maximal biological activity. To obtain insights into the mechanism by which E1A hijacks the cellular transcription machinery by competing with essential transcription factors for binding to CBP/p300, we have determined the structure of the complex between the transcriptional adaptor zinc finger-2 (TAZ2) domain of CBP and the conserved region-1 (CR1) domain of E1A. The E1A CR1 domain is unstructured in the free state and upon binding folds into a local helical structure mediated by an extensive network of intermolecular hydrophobic contacts. By NMR titrations, we show that E1A efficiently competes with the N-terminal transactivation domain of p53 for binding to TAZ2 and that pRb interacts with E1A at 2 independent sites located in CR1 and CR2. We show that pRb and the CBP TAZ2 domain can bind simultaneously to the CR1 site of E1A to form a ternary complex and propose a structural model for the pRb: E1A: CBP complex on the basis of published x-ray data for homologous binary complexes. These observations reveal the molecular basis by which E1A inhibits p53-mediated transcriptional activation and provide a rationale for the efficiency of cellular transformation by the adenoviral E1A oncoprotein.