Interaction between p53 N terminus and core domain regulates specific and nonspecific DNA binding
Interaction between p53 N terminus and core domain regulates specific and nonspecific DNA binding
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DOI：
10.1073/pnas.1903077116
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发表时间：
2019-04-30
影响因子：
11.1
通讯作者：
Chen, Jiandong
中科院分区：
文献类型：
--
作者：
He, Fan;Borcherds, Wade;Chen, Jiandong
p53肿瘤抑制因子是一种序列特异性DNA结合蛋白，其激活基因转录以调节细胞存活和增殖。响应于应激信号的p53降解和DNA结合的动态控制对于肿瘤抑制至关重要。p53的N端（NT）含有两个反式激活结构域（TAD 1和TAD 2），一个富含脯氨酸的区域（PRR），和多个磷酸化位点。先前的工作揭示了p53 NT在体外减少DNA结合。在这里，我们表明，TAD 2和PRR通过直接与序列特异性DNA结合结构域（DBD）相互作用来抑制DNA结合。NMR光谱显示TAD 2和PRR在DNA结合表面处或附近与DBD相互作用，可能充当核酸模拟物以竞争性地阻断DNA结合。体外和体内DNA结合分析表明，NT降低了p53 DNA结合亲和力，但提高了p53区分特异性和非特异性序列的能力。MDMX抑制p53与特异性靶启动子的结合，但刺激与非特异性染色质位点的结合。结果表明，p53 NT调节DBD与DNA结合的亲和力和特异性。p53 NT相互作用蛋白和翻译后修饰可以调节DNA结合，部分通过调节NT-DBD相互作用。
The p53 tumor suppressor is a sequence-specific DNA binding protein that activates gene transcription to regulate cell survival and proliferation. Dynamic control of p53 degradation and DNA binding in response to stress signals are critical for tumor suppression. The p53 N terminus (NT) contains two transactivation domains (TAD1 and TAD2), a proline-rich region (PRR), and multiple phosphorylation sites. Previous work revealed the p53 NT reduced DNA binding in vitro. Here, we show that TAD2 and the PRR inhibit DNA binding by directly interacting with the sequence-specific DNA binding domain (DBD). NMR spectroscopy revealed that TAD2 and the PRR interact with the DBD at or near the DNA binding surface, possibly acting as a nucleic acid mimetic to competitively block DNA binding. In vitro and in vivo DNA binding analyses showed that the NT reduced p53 DNA binding affinity but improved the ability of p53 to distinguish between specific and nonspecific sequences. MDMX inhibits p53 binding to specific target promoters but stimulates binding to nonspecific chromatin sites. The results suggest that the p53 NT regulates the affinity and specificity of DNA binding by the DBD. The p53 NT-interacting proteins and posttranslational modifications may regulate DNA binding, partly by modulating the NT-DBD interaction.