Ricci Caterina, Ortore Maria Grazia, Vilasi Silvia, Carrotta Rita, Mangione Maria Rosalia, Bulone Donatella, Librizzi Fabio, Spinozzi Francesco, Burgio Giosalba, Amenitsch Heinz, San Biagio Pier Luigi
Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona 60131, Italy.
Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona 60131, Italy.
Biophys Chem. 2016 Jan;208:68-75. doi: 10.1016/j.bpc.2015.07.006. Epub 2015 Jul 30.
Human Hsp60 chaperonin and its bacterial homolog GroEL, in association with the corresponding co-chaperonins Hsp10 and GroES, constitute important chaperone systems promoting the proper folding of several mitochondrial proteins. Hsp60 is also currently described as a ubiquitous molecule with multiple roles both in health conditions and in several diseases. Naïve Hsp60 bearing the mitochondrial import signal has been recently demonstrated to present different oligomeric organizations with respect to GroEL, suggesting new possible physiological functions. Here we present a combined investigation with circular dichroism and small-angle X-ray scattering of structure, self-organization, and stability of naïve Hsp60 in solution in comparison with bacterial GroEL. Experiments have been performed in different concentrations of guanidine hydrochloride, monitoring the dissociation of tetradecamers into heptamers and monomers, until unfolding. GroEL is proved to be more stable with respect to Hsp60, and the unfolding free energy as well as its dependence on denaturant concentration is obtained.
人类热休克蛋白60伴侣蛋白及其细菌同源物GroEL，与相应的共伴侣蛋白Hsp10和GroES结合，构成了促进几种线粒体蛋白正确折叠的重要伴侣系统。热休克蛋白60目前也被描述为一种普遍存在的分子，在健康状况和多种疾病中都发挥着多种作用。最近有研究表明，带有线粒体导入信号的天然热休克蛋白60与GroEL相比呈现出不同的寡聚结构，这提示了新的可能的生理功能。在这里，我们结合圆二色光谱和小角X射线散射技术，对溶液中天然热休克蛋白60与细菌GroEL的结构、自组装和稳定性进行了联合研究。实验在不同浓度的盐酸胍中进行，监测十四聚体解离为七聚体和单体的过程，直至蛋白解折叠。结果表明，GroEL相对于热休克蛋白60更稳定，并获得了其解折叠自由能及其对变性剂浓度的依赖性。
