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4D Imaging of Protein Aggregation in Live Cells
Published on: April 5, 2013
大分子拥挤不能折叠细胞中的球状蛋白质
Alexander P Schlesinger1, Yaqiang Wang, Xavier Tadeo
1Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Journal of the American Chemical Society
|May 4, 2011
概括
细胞拥挤通过排斥体积稳定蛋白质,但非特异性相互作用可以抵消这种效应. 研究表明大肠杆菌细胞质不能完全稳定蛋白质变体,这表明这些相互作用是显著的.
科学领域:
- 生物化学 生物化学
- 生物物理学的生物物理.
- 分子生物学分子生物学
背景情况:
- 细胞环境是拥挤的,宏分子占据超过30%的体积.
- 这种拥挤创造了一个排除体积效应,热力学上有利于紧,折叠的蛋白质状态.
- 理论模型预测了由于被排除的体积而导致的显著蛋白质稳定.
研究的目的:
- 为了研究排除体积对细胞环境中的蛋白质稳定性影响的主导地位.
- 确定大肠杆菌的细胞质是否为部分展开的蛋白质变体提供预测的稳定性.
- 探索非特异性相互作用在 vivo 中调节蛋白质稳定性的作用.
主要方法:
- 使用一种蛋白质L变体,在稀释溶液中稳定性降低 (84%变质).
- 采用细胞内核磁共振 (NMR) 光谱,以评估活体大肠杆菌中蛋白质折叠状态.
- 在体外和体内实验中进行了盐添加的实验,以探测相互作用.
主要成果:
- 蛋白质L变体在大肠杆菌细胞质中仍然在很大程度上变质,这表明稳定性有限 (~1kcal/mol自由能量赤字).
- 将盐添加到稀释溶液中的变体中诱导了折叠,与排除体积效应一致.
- 增加大肠杆菌中的盐度并没有导致该变种的显著折叠.
结论:
- 细胞质成分之间的非特异性相互作用可以抵消排除体积的稳定作用.
- 细胞环境对蛋白质稳定性的净影响是排除体积有利性和破坏性非特异性相互作用之间的平衡.
- 这些发现表明,被排除的体积稳定被其他因素 in vivo 改善.
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