Two p53 tetramers bind one consensus DNA response element.
Two p53 tetramers bind one consensus DNA response element.
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DOI：
10.1093/nar/gkw215
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发表时间：
2016-07-27
影响因子：
14.9
通讯作者：
Okorokov AL
中科院分区：
文献类型：
--
作者：
Kearns S;Lurz R;Orlova EV;Okorokov AL
p53肿瘤抑制因子是控制细胞周期和遗传完整性的转录因子。在响应遗传毒性应激时，p53激活DNA修复、细胞周期停滞、凋亡或衰老，这些都是通过p53与其特异性DNA响应元件（RE）结合而启动的。共有p53 DNA RE由两个十聚体回文半位点序列组成。晶体学研究表明，两个分离的p53 DNA结合核心结构域与p53 DNA RE的一个半位点相互作用，表明一个p53四聚体与一个RE结合。然而，我们最近的3D冷冻电镜研究表明，全长p53四聚体仅结合到RE的一个半位点。在这里，我们已经使用生物化学和电子显微镜（EM）的方法来分析DNA结合的人和小鼠p53四聚体的各种p53 DNA REs. Our新的结果表明，两个p53四聚体可以相互作用的序列特异性在同一时间与一个DNA RE。特别地，EM结构分析揭示了两个p53四聚体同时结合一个DNA RE，其中DNA位于它们之间。这些结果表明，模式不同于先前假设的p53-DNA相互作用，并建议重要的生物学意义上的p53活性作为一个转录调节细胞应激反应。
p53 tumor suppressor is a transcription factor that controls cell cycle and genetic integrity. In response to genotoxic stress p53 activates DNA repair, cell cycle arrest, apoptosis or senescence, which are initiated via p53 binding to its specific DNA response elements (RE). The consensus p53 DNA RE consists of two decameric palindromic half-site sequences. Crystallographic studies have demonstrated that two isolated p53 DNA-binding core domains interact with one half-site of the p53 DNA REs suggesting that one p53 tetramer is bound to one RE. However, our recent 3D cryo-EM studies showed that the full-length p53 tetramer is bound to only one half-site of RE. Here, we have used biochemical and electron microscopy (EM) methods to analyze DNA-binding of human and murine p53 tetramers to various p53 DNA REs. Our new results demonstrate that two p53 tetramers can interact sequence-specifically with one DNA RE at the same time. In particular, the EM structural analysis revealed that two p53 tetramers bind one DNA RE simultaneously with DNA positioned between them. These results demonstrate a mode different from that assumed previously for the p53-DNA interaction and suggest important biological implications on p53 activity as a transcriptional regulator of cellular response to stress.