Single-Molecule Force Spectroscopy Identifies a Small Cold Shock Protein as Being Mechanically Robust
Single-Molecule Force Spectroscopy Identifies a Small Cold Shock Protein as Being Mechanically Robust
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DOI：
10.1021/jp310442s
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发表时间：
2013-02-14
影响因子：
3.3
通讯作者：
Dougan, Lorna
中科院分区：
文献类型：
--
作者：
Hoffmann, Toni;Tych, Katarzyna M.;Dougan, Lorna
单分子力谱已成为一种强有力的方法来检查单蛋白质的稳定性和动力学。我们已经完成了力延伸实验的小冷休克蛋白B从海栖热袍菌，使用一个特别构建的嵌合多聚蛋白。该蛋白质的简单拓扑结构，这是不同于机械wellcharacterized /9-把握和免疫球蛋白（IG）样的褶皱，除了广泛的结构同源物从其古老的起源，提供了一个有吸引力的模型蛋白质的单分子力谱研究。我们已经确定该蛋白具有机械稳定性，在100 nm s（-1）的拉伸速度下以大于70 pN展开。我们揭示了功能的展开能量景观通过测量的机械稳定性对拉速度的依赖性，结合蒙特卡罗模拟。我们表明，冷休克蛋白具有机械鲁棒性，但可塑性，功能可能是重要的，在提供蛋白质的稳定性和灵活性，在一系列的环境条件下发挥作用。这些结果提供了深入了解蛋白质的二级结构和拓扑结构与其机械强度之间的关系。这为研究环境条件变化对冷休克蛋白力学和动力学性质的影响奠定了基础。
Single-molecule force spectroscopy has emerged as a powerful approach to examine the stability and dynamics of single proteins. We have completed force extension experiments on the small cold shock protein B from Thermotoga maritima, using a specially constructed chimeric polyprotein. The protein's simple topology, which is distinct from the mechanically wellcharacterized /9-grasp and immunoglobulin (Ig)-like folds, in addition to the wide range of structural homologues resulting from its ancient origin, provides an attractive model protein for single-molecule force spectroscopy studies. We have determined that the protein has mechanical stability, unfolding at greater than 70 pN at a pulling velocity of 100 nm s(-1) . We reveal features of the unfolding energy landscape by measuring the dependence of the mechanical stability on pulling velocity, in combination with Monte Carlo simulations. We show that the cold shock protein has mechanically robust, yet malleable, features that may be important in providing the protein with stability and flexibility to function over a range of environmental conditions. These results provide insights into the relationship between the secondary structure and topology of a protein and its mechanical strength. This lays the foundation for the investigation of the effects of changes in environmental conditions on the mechanical and dynamic properties of cold shock proteins.