MOE Key Laboratory for Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China.
Nucleic Acids Res. 2011 May;39(10):4464-74. doi: 10.1093/nar/gkr030. Epub 2011 Jan 29.
Transcription co-activators CBP and p300 are recruited by sequence-specific transcription factors to specific genomic loci to control gene expression. A highly conserved domain in CBP/p300, the TAZ2 domain, mediates direct interaction with a variety of transcription factors including the myocyte enhancer factor 2 (MEF2). Here we report the crystal structure of a ternary complex of the p300 TAZ2 domain bound to MEF2 on DNA at 2.2Å resolution. The structure reveals three MEF2:DNA complexes binding to different sites of the TAZ2 domain. Using structure-guided mutations and a mammalian two-hybrid assay, we show that all three interfaces contribute to the binding of MEF2 to p300, suggesting that p300 may use one of the three interfaces to interact with MEF2 in different cellular contexts and that one p300 can bind three MEF2:DNA complexes simultaneously. These studies, together with previously characterized TAZ2 complexes bound to different transcription factors, demonstrate the potency and versatility of TAZ2 in protein-protein interactions. Our results also support a model wherein p300 promotes the assembly of a higher-order enhanceosome by simultaneous interactions with multiple DNA-bound transcription factors.
转录共激活因子 CBP 和 p300 通过序列特异性转录因子被招募到特定的基因组位置，以控制基因表达。CBP/p300 中的一个高度保守结构域——TAZ2 结构域，介导了与多种转录因子的直接相互作用，包括肌细胞增强因子 2（MEF2）。在这里，我们报道了 p300 TAZ2 结构域与 DNA 上 MEF2 的三元复合物的晶体结构，分辨率为 2.2Å。该结构揭示了三个 MEF2:DNA 复合物结合到 TAZ2 结构域的不同位点。通过结构引导的突变和哺乳动物双杂交测定，我们表明所有三个界面都有助于 MEF2 与 p300 的结合，这表明 p300 可能在不同的细胞环境中使用三个界面之一与 MEF2 相互作用，并且一个 p300 可以同时结合三个 MEF2:DNA 复合物。这些研究，连同先前表征的与不同转录因子结合的 TAZ2 复合物一起，证明了 TAZ2 在蛋白-蛋白相互作用中的效力和多功能性。我们的结果也支持了这样一种模型，即 p300 通过与多个 DNA 结合的转录因子的同时相互作用，促进了更高阶增强子复合物的组装。
