Hu Bin, Mayer Matthias P, Tomita Masaru
Institute for Advanced Biosciences, and Graduate School of Media and Governance, Keio University, Tsuruoka, Japan.
Biophys J. 2006 Jul 15;91(2):496-507. doi: 10.1529/biophysj.106.083394. Epub 2006 Apr 28.
The Hsp70 chaperone system is the major molecular chaperone system that assists protein-folding processes in all cells. To understand these processes, we analyzed the kinetic characteristics of the Escherichia coli homologs of this chaperone system during folding of a denatured protein using computer simulations and compared the results with in vitro refolding experiments. Rate constants used for the model were derived from recent literature or were determined and scrutinized for their applicability to the refolding reaction. Our simulation results are consistent with reported laboratory experiments, not only simulating the refolding reaction of wild-type proteins but also the behavior of mutant variants. Variation of kinetic parameters and concentrations of components of the Hsp70 system demonstrate the robustness of the chaperone system in assisting protein folding. Furthermore, the importance of the synergistic stimulation of the ATPase activity of Hsp70 is demonstrated. The limitations of our kinetic model indicate sore spots in our understanding of this chaperone system. Our model provides a platform for further research on chaperone action and the mechanism of chaperone-assisted refolding of denatured proteins.
热休克蛋白70（Hsp70）伴侣系统是协助所有细胞中蛋白质折叠过程的主要分子伴侣系统。为了理解这些过程，我们使用计算机模拟分析了该伴侣系统的大肠杆菌同源物在变性蛋白折叠过程中的动力学特征，并将结果与体外重折叠实验进行了比较。模型中使用的速率常数来自近期文献，或经过测定并仔细检查其对重折叠反应的适用性。我们的模拟结果与已报道的实验室实验一致，不仅模拟了野生型蛋白的重折叠反应，还模拟了突变体变体的行为。Hsp70系统动力学参数和组分浓度的变化证明了伴侣系统在协助蛋白质折叠方面的稳健性。此外，还证明了对Hsp70 ATPase活性协同刺激的重要性。我们动力学模型的局限性表明了我们对该伴侣系统理解中的薄弱环节。我们的模型为进一步研究伴侣作用以及伴侣辅助变性蛋白重折叠的机制提供了一个平台。
