Single-Molecule Spectroscopy Study of Crowding-Induced Protein Spontaneous Denature and Crowding-Perturbed Unfolding-Folding Conformational Fluctuation Dynamics.
Single-Molecule Spectroscopy Study of Crowding-Induced Protein Spontaneous Denature and Crowding-Perturbed Unfolding-Folding Conformational Fluctuation Dynamics.
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DOI：
10.1021/acs.jpcb.8b03119
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
Zijian Wang;H. Lu
中科院分区：
文献类型：
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作者：
Zijian Wang;H. Lu
分子拥挤对蛋白质折叠-去折叠过程的影响对于理解活细胞中蛋白质的功能和结构动力学具有重要意义。在分子拥挤的情况下，由于减少了熵效应，蛋白质的稳定性得到了很好的提高，这在实验和理论上都是很好的理解。然而，由于在蛋白质折叠和去折叠构象动力学同等有利的环境中存在的各种相互作用的复杂性和相互作用，这种简单的约化熵增强模型不足以描述蛋白质拥挤条件下的蛋白质折叠构象动力学。本文报道了在拥挤试剂Ficoll70溶液中，单个蛋白质分子自发变性为未折叠蛋白质以及折叠-去折叠波动的观察结果。我们已经确认，这种蛋白质动力学涉及聚合物-聚合物相互作用、熵效应和蛋白质溶剂化动力学的综合机制。我们利用单分子光谱学对蛋白质折叠-展开动力学进行表征，以获得关于蛋白质折叠-展开构象涨落动力学的详细的分子动态尺度信息。我们的发现表明，复杂的展开动力学过程是由分子拥挤效应引起的单个蛋白质分子的自发变性，这在系综平均测量中一直难以分析。此外，自发展开所需的能量处于生物可及力波动水平，这表明这对人类健康具有重要的相关性和重要性。对非均一蛋白质展开过程的新知识可以作为对与分子拥挤、蛋白质聚集体、纤维形成以及通常在分子拥挤的局部环境下的基因翻译调节过程相关的人类疾病的机械性理解的一步。
The effects of molecular crowding on protein folding-unfolding processes are of importance for understanding protein function and structure dynamics in living cells. The enhancement of protein stability as a result of reduced entropic effect in the presence of molecular crowding is well understood both experimentally and theoretically. However, because of the complexity and interplay between various interactions existing in an equally favored environment of protein folding and unfolding conformational dynamics, such a simple reduced entropic enhancement model does not suffice to describe protein folding conformational dynamics under a protein crowding condition. In this paper, we report our observation on that single protein molecules spontaneously denature into unfolded proteins and folding-unfolding fluctuations in solution of crowding reagent Ficoll 70. We have identified that such protein dynamics involves a combined mechanism of polymer-polymer interaction, entropic effects, and protein solvation dynamics. We characterize the protein folding-unfolding dynamics by using single-molecule spectroscopy to obtain detailed molecular dynamic scale information on the protein folding-unfolding conformational fluctuation dynamics. Our findings suggest that the complex unfolding dynamic processes are spontaneous denature of single protein molecules induced by molecular crowding effect which has been elusive for analysis in ensemble-averaged measurements. Furthermore, the energy needed for the spontaneous unfolding is at the biological accessible force fluctuation level, which suggests a strong implication of significant human health relevance and importance. The new knowledge of the inhomogeneous protein unfolding processes can serve as a step forward to a mechanistic understanding of human diseases associated with molecular crowding, protein aggregates, fibril formation, as well as gene translational regulation processes typically under a molecular crowded local environment.