在陪伴者GroEL腔中探测水密度和动态
John M Franck1, Miri Sokolovski, Naama Kessler
1Department of Chemistry and Biochemistry, University of California Santa Barbara, California 93106, United States.
Journal of the American Chemical Society
|June 4, 2014
概括
限制在GroEL-GroES chaperonin复合体内的水表现类似于散装水,挑战了关于蛋白质折叠环境的先前假设. 这一发现表明,沙佩罗宁腔内的水特性不会显著阻碍蛋白质折叠.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 生物物理学的生物物理.
背景情况:
- 护卫蛋白GroEL及其辅因子GroES形成了一个用于蛋白质折叠的狭窄腔.
- 封闭水特性 (密度,动态) 的潜在差异可能会影响封装蛋白质折叠与散装溶液相比.
- 此前,关于空洞内水的特性的实验数据缺乏.
研究的目的:
- 实验性地研究GroEL-GroES综合体内的水的密度和扩散动态.
- 为了比较腔内水的特性与GroES表面暴露的散水.
- 了解这些水性质对沙佩罗宁辅助蛋白质折叠的影响.
主要方法:
- 使用了一种GroES突变,在残留物71 (Tyr71 → Cys) 处标有旋转标签.
- 采用电子旋转回声封膜调制和Overhauser动态核极化来测量旋转标签附近的水特性.
- 在自由GroES (批量暴露) 和GroEL-GroES复合体 (腔内限制) 中比较水的特性.
主要成果:
- 在GroES表面附近的水密度和转换动态在GroEL-GroES复合体形成时保持不变.
- 这表明,暴露于散装的表面水和被封闭在腔内的水具有相似的特性.
- 发现GroES表面附近的水扩散动态与其他研究的蛋白质表面相比异常快.
结论:
- 在GroEL-GroES综合体内,空洞封闭的水表现出与散装水相似的特性.
- 在GroES表面异常快速的水扩散可能起到Chaperonin辅助折叠机制的作用.
- 这些发现表明,固体封闭和腔体相互作用,而不是散装水的差异,是Chaperonin介导折叠的关键因素.
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