Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
Biochim Biophys Acta Mol Cell Res. 2022 Oct;1869(10):119319. doi: 10.1016/j.bbamcr.2022.119319. Epub 2022 Jun 30.
The tumor suppressor protein p53 governs many cellular pathways to control genome integrity, metabolic homeostasis, and cell viability. The critical roles of p53 highlight the importance of proper control over p53 in maintaining normal cellular function, with the negative regulators MDM2 and MDMX playing central roles in regulating p53 activity. The interaction between p53 and either MDM2 or MDMX involves the p53 transactivation domain (p53TD) and the N-terminal domains (NTD) of MDM2 or MDMX. Recently, the acidic domain (AD) of MDMX was found to bind to its own NTD, inhibiting the p53-MDMX interaction. Given the established structural and functional similarity between the MDM2 and MDMX NTDs, we hypothesized that the MDMX AD would also directly bind to MDM2 NTD to inhibit p53-MDM2 interaction. Through solution-state nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry (ITC), we show that the MDMX AD can indeed directly interact with the MDM2 NTD and, as a result, can compete for p53 binding. The MDMX AD is thus able to serve as a regulatory domain to inhibit the MDM2-p53 interaction and may also play a direct role in p53 activation.
肿瘤抑制蛋白 p53 调控许多细胞通路以控制基因组完整性、代谢稳态和细胞活力。p53 的关键作用突显了适当控制 p53 对于维持正常细胞功能的重要性，负调节因子 MDM2 和 MDMX 在调节 p53 活性方面发挥着核心作用。p53 与 MDM2 或 MDMX 的相互作用涉及 p53 转录激活结构域（p53TD）和 MDM2 或 MDMX 的 N 端结构域（NTD）。最近发现 MDMX 的酸性结构域（AD）与自身的 NTD 结合，抑制 p53-MDMX 相互作用。鉴于 MDM2 和 MDMX NTD 之间已建立的结构和功能相似性，我们假设 MDMX AD 也会直接与 MDM2 NTD 结合，从而抑制 p53-MDM2 相互作用。通过溶液态核磁共振（NMR）光谱和等温滴定量热法（ITC），我们表明 MDMX AD 确实可以直接与 MDM2 NTD 相互作用，并且可以与 p53 竞争结合。因此，MDMX AD 可以作为调节结构域来抑制 MDM2-p53 相互作用，并且可能在 p53 激活中也发挥直接作用。
