Graded enhancement of p53 binding to CREB-binding protein (CBP) by multisite phosphorylation
Graded enhancement of p53 binding to CREB-binding protein (CBP) by multisite phosphorylation
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DOI：
10.1073/pnas.1013078107
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发表时间：
2010-11-09
影响因子：
11.1
通讯作者：
Wright, Peter E.
中科院分区：
文献类型：
--
作者：
Lee, Chul Won;Ferreon, Josephine C.;Wright, Peter E.
p53的转录活性受一系列翻译后修饰的调控。虽然已知CREB结合蛋白（CBP）/p300对p53的乙酰化是p53激活不可或缺的，但磷酸化，特别是多位点磷酸化在CBP/p300依赖性p53转录途径激活中的作用仍不清楚。我们研究了p53反式激活结构域的单位点和多位点磷酸化在介导其与CBP和泛素连接酶HDM 2相互作用中的作用。Thr 18处的磷酸化作为开/关开关起作用以调节与HDM 2的N-末端结构域的结合。相反，与CBP的结合受p53磷酸化程度的调节;添加连续的磷酰基团以相加的方式增强了对CBP的TAZ 1、TAZ 2和KIX结构域的亲和力。p53依赖性转录途径的激活需要p53与许多细胞转录因子竞争结合有限量的CBP/p300。多位点磷酸化代表了分级p53应答的机制，在面对来自细胞转录因子的竞争时，每个连续的磷酸化事件导致CBP/p300越来越有效地募集到p53调节的转录程序。因此，多位点磷酸化充当可变电阻器，增强与CBP/p300的结合，并为长期或严重遗传毒性应激后观察到的逐渐增加的p53反应提供了合理的机制解释。
The transcriptional activity of p53 is regulated by a cascade of posttranslational modifications. Although acetylation of p53 by CREB-binding protein (CBP)/p300 is known to be indispensable for p53 activation, the role of phosphorylation, and in particular multisite phosphorylation, in activation of CBP/p300-dependent p53 transcriptional pathways remains unclear. We investigated the role of single site and multiple site phosphorylation of the p53 transactivation domain in mediating its interaction with CBP and with the ubiquitin ligase HDM2. Phosphorylation at Thr18 functions as an on/off switch to regulate binding to the N-terminal domain of HDM2. In contrast, binding to CBP is modulated by the extent of p53 phosphorylation; addition of successive phosphoryl groups enhances the affinity for the TAZ1, TAZ2, and KIX domains of CBP in an additive manner. Activation of p53-dependent transcriptional pathways requires that p53 compete with numerous cellular transcription factors for binding to limiting amounts of CBP/p300. Multisite phosphorylation represents a mechanism for a graded p53 response, with each successive phosphorylation event resulting in increasingly efficient recruitment of CBP/p300 to p53-regulated transcriptional programs, in the face of competition from cellular transcription factors. Multisite phosphorylation thus acts as a rheostat to enhance binding to CBP/p300 and provides a plausible mechanistic explanation for the gradually increasing p53 response observed following prolonged or severe genotoxic stress.