Miller Jenkins Lisa M, Feng Hanqiao, Durell Stewart R, Tagad Harichandra D, Mazur Sharlyn J, Tropea Joseph E, Bai Yawen, Appella Ettore
†Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States.
‡Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States.
Biochemistry. 2015 Mar 24;54(11):2001-10. doi: 10.1021/acs.biochem.5b00044. Epub 2015 Mar 16.
The p53 tumor suppressor is a critical mediator of the cellular response to stress. The N-terminal transactivation domain of p53 makes protein interactions that promote its function as a transcription factor. Among those cofactors is the histone acetyltransferase p300, which both stabilizes p53 and promotes local chromatin unwinding. Here, we report the nuclear magnetic resonance solution structure of the Taz2 domain of p300 bound to the second transactivation subdomain of p53. In the complex, p53 forms an α-helix between residues 47 and 55 that interacts with the α1-α2-α3 face of Taz2. Mutational analysis indicated several residues in both p53 and Taz2 that are critical for stabilizing the interaction. Finally, further characterization of the complex by isothermal titration calorimetry revealed that complex formation is pH-dependent and releases a bound chloride ion. This study highlights differences in the structures of complexes formed by the two transactivation subdomains of p53 that may be broadly observed and play critical roles in p53 transcriptional activity.
p53肿瘤抑制蛋白是细胞应激反应的关键调节因子。p53的N端反式激活结构域通过蛋白质相互作用发挥转录因子的功能。其中一个辅助因子是组蛋白乙酰转移酶p300，它既能稳定p53，又能促进局部染色质解旋。在此，我们报道了与p53第二个反式激活亚结构域结合的p300的Taz2结构域的核磁共振溶液结构。在该复合物中，p53在47至55位残基之间形成一个α螺旋，与Taz2的α1-α2-α3面相互作用。突变分析表明，p53和Taz2中的几个残基对稳定这种相互作用至关重要。最后，通过等温滴定量热法对该复合物进行进一步表征，结果表明复合物的形成依赖于pH值，并释放出一个结合的氯离子。这项研究突出了p53两个反式激活亚结构域形成的复合物结构差异，这些差异可能普遍存在，并在p53转录活性中起关键作用。
