Measuring protein stability in the GroEL chaperonin cage reveals massive destabilization
Measuring protein stability in the GroEL chaperonin cage reveals massive destabilization
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DOI：
10.7554/elife.56511
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发表时间：
2020-07-27
期刊：
影响因子：
7.7
通讯作者：
Horovitz, Amnon
中科院分区：
文献类型：
--
作者：
Korobko, Ilia;Mazal, Hisham;Horovitz, Amnon
蛋白质在体溶液中折叠的热力学已经被深入研究了几十年。相比之下，对GroEL/ES伴侣蛋白笼内蛋白质底物稳定性的测量尚未见报道。这种测量需要稳定的封装，即在实验过程中底物不会逃逸到散装溶液中，并且在不影响伴侣蛋白系统本身的情况下扰乱蛋白质稳定性。在这里，通过建立这样的条件，我们表明，与散装溶液相比，伴侣蛋白笼中的蛋白质稳定性显著降低了5千卡摩尔（-1）以上。考虑到空间约束本身是稳定的，我们的结果表明，在腔中的疏水和/或静电效应是强烈的不稳定。我们的发现与提出的伴侣蛋白GroEL的迭代退火作用机制一致。
The thermodynamics of protein folding in bulk solution have been thoroughly investigated for decades. By contrast, measurements of protein substrate stability inside the GroEL/ES chaperonin cage have not been reported. Such measurements require stable encapsulation, that is no escape of the substrate into bulk solution during experiments, and a way to perturb protein stability without affecting the chaperonin system itself. Here, by establishing such conditions, we show that protein stability in the chaperonin cage is reduced dramatically by more than 5 kcal mol(-1) compared to that in bulk solution. Given that steric confinement alone is stabilizing, our results indicate that hydrophobic and/or electrostatic effects in the cavity are strongly destabilizing. Our findings are consistent with the iterative annealing mechanism of action proposed for the chaperonin GroEL.