Higurashi Takashi, Yagi Hisashi, Mizobata Tomohiro, Kawata Yasushi
Department of Biotechnology, Faculty of Engineering, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Koyama-Minami, Tottori 680-8552, Japan.
J Mol Biol. 2005 Sep 2;351(5):1057-69. doi: 10.1016/j.jmb.2005.07.006.
The molecular chaperone GroES, together with GroEL from Escherichia coli, is the best characterized protein of the molecular chaperone family. Here, we report on the in vitro formation of GroES amyloid-like fibrils and the mechanism of formation. When incubated for several weeks at neutral pH in the presence of the denaturant guanidine hydrochloride, GroES formed a typical amyloid fibril; unbranched, twisted, and extended filaments stainable by thioflavin T and Congo red. GroES fibril formation was accelerated by the addition of preformed fibril seeds, in accordance with a nucleation-extension mechanism. Interestingly, whereas the spontaneous formation of GroES fibrils was favored in the structural transition region of GroES dissociation/unfolding, the extension of fibrils from preformed fibril seeds was favored in the region corresponding to an expanded molecular state. We concluded that the two stages of GroES fibril formation prefer different molecular states of the same protein. The significance of this preference is discussed.
分子伴侣GroES与来自大肠杆菌的GroEL一起，是分子伴侣家族中特征最明确的蛋白质。在此，我们报道了GroES类淀粉样纤维的体外形成及其形成机制。当在变性剂盐酸胍存在下于中性pH孵育数周时，GroES形成了典型的淀粉样纤维；未分支、扭曲且延伸的细丝可被硫黄素T和刚果红染色。根据成核-延伸机制，添加预先形成的纤维种子可加速GroES纤维的形成。有趣的是，虽然GroES纤维的自发形成在GroES解离/展开的结构转变区域更有利，但预先形成的纤维种子上纤维的延伸在对应于扩展分子状态的区域更有利。我们得出结论，GroES纤维形成的两个阶段偏好同一蛋白质的不同分子状态。本文讨论了这种偏好的意义。
