Trp146 of the p53 DNA-binding domain (DBD) was investigated by static and time-resolved fluorescence combined with molecular dynamics (MD) simulations at different temperatures (25, 30, 37, and 45 °C). Static emission spectra exhibit an intensity maximum at 30 °C without any substantial peak shift, while the time-resolved fluorescence displays a peculiar stretched exponential decay, indicative of a structural disorder, at all of the investigated temperatures. The stretched exponential parameter was found to increase at 37 °C. An analysis of the MD simulation trajectories evidenced the occurrence of jumps in the temporal evolution of the distances between Trp146 and residues Arg110, Asp228, Cys229, and Gln144, which are mainly responsible for Trp146 fluorescence quenching. The times that these quenchers spend close to or far from Trp146 can provide an explanation for the static fluorescence behavior. Further essential dynamics analysis of the MD trajectories indicates a significant restriction of protein global motions above 37 °C. These results are consistent with a decrease in the structural heterogeneity of DBD as the temperature increases. The results are also discussed in view of understanding how temperature can modulate the p53 capability to binding partners, including DNA.

中文翻译：

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通过静态和时间分辨荧光结合分子动力学模拟监测 DBDp53 结构的温度调制

p53 DNA 结合域 (DBD) 的 Trp146 通过静态和时间分辨荧光结合分子动力学 (MD) 模拟在不同温度 (25、30、37 和 45 °C) 下进行研究。静态发射光谱在 30 °C 时表现出强度最大值，而没有任何实质性的峰移，而时间分辨荧光显示出特殊的拉伸指数衰减，表明在所有研究温度下都存在结构紊乱。发现拉伸指数参数在 37°C 时增加。对 MD 模拟轨迹的分析证明 Trp146 与残基 Arg110、Asp228、Cys229 和 Gln144 之间距离的时间演化发生了跳跃，这些残基主要负责 Trp146 荧光猝灭。这些猝灭剂接近或远离 Trp146 的时间可以解释静态荧光行为。MD 轨迹的进一步基本动力学分析表明蛋白质全局运动在 37°C 以上受到显着限制。这些结果与随着温度升高 DBD 结构异质性的降低一致。还讨论了结果，以了解温度如何调节 p53 与结合伙伴（包括 DNA）的能力。