Protein conformational changes and molecular chaperone

为了了解负责生物功能的蛋白质三级结构是如何发生的，以及分子伴侣是如何参与这一事件的，我们研究了各种蛋白质的稳定性和构象变化，阐明了蛋白质淀粉样原纤维形成的分子机制。此外，我们对分子伴侣尤其是伴侣蛋白的作用机理进行了详细的研究，得到了以下结果。伴侣蛋白机制的研究：我们从蛋白质科学和生物物理的角度，详细研究了来自大肠杆菌的第一类伴侣蛋白GroEL和来自耐高温菌株的第二类伴侣蛋白GroEL的结构和功能关系。我们发现GroEL的结构域移动对其功能非常重要，钴和锰离子是影响第二组伴侣蛋白核苷酸水解性和底物折叠功能的新因素。蛋白淀粉样原纤维形成机制的研究：我们发现寡聚蛋白…GROES是一种与疾病无关的蛋白质，在未折叠的条件下形成典型的淀粉样纤维，并从分子致密性的角度阐明了纤维形成的机制。此外，我们还研究了帕金森氏病的致病蛋白α-突触核蛋白的纤维形成机制，并证明了在其他不同蛋白质的纤维的预制种子的存在下，α-突触核蛋白的淀粉样纤维的形成明显加速。低聚蛋白的结构和稳定性研究：测定了耐热天冬氨酸酶的X射线晶体结构，阐明了该酶由4个相同亚基组成的热稳定性机理和活性中心结构。另一方面，我们利用小角X射线散射法研究了高蛋白浓度下大肠杆菌辅伴蛋白Groes七聚体的溶液结构和分子解折叠机制。此外，我们还阐明了亚基相互作用对整体结构稳定性的重要作用。较少

In order to understand how protein tertiary structure that is responsible for biofunction occurs and how molecular chaperones are involved in the event, we studied stabilities and conformational changes of various proteins, and clarified molecular mechanism of protein amyloid fibril formation. Furthermore, we studied functional mechanism of molecular chaperone, especially, chaperonins in detail, and obtained following results.1. Study on chaperonin mechanism: We have studied in detail structure and function relationship of group I chaperonin GroEL from E. coli and group II chaperonins from hyper-thermostable strains, from protein science and biophysical points of view. We have found that domain movements of GroEL are very important for the function and that cobalt and manganese ions are novel factors for nucleotide hydrolysis activity and substrate refolding function of group II chaperonin.2. Study on mechanism of protein amyloid fibril formation: We have found that oligomeric protein … More GroES, that is a non-related protein to disease, formed typical amyloid fibrils under unfolded conditions, and elucidated the fibril formation mechanism in terms of molecular compactness. Furthermore, we studied fibril formation mechanism of α-synuclein, that is a causative protein of Parkinson's disease, and proved that the amyloid fibril formation of α-synuclein is accelerated markedly in the presence of preformed seeds of other different protein's fibrils.3. Study on structure and stability of oligomeric protein: We have determined the X-ray crystal structure of thermostable aspartase enzyme, and elucidated the mechanism of thermostability and active site structure of the enzyme comprising from 4 identical subunits. On the other hand, we studied solution structure and molecular unfolding mechanism of E. coli co-chaperonin GroES heptamer at high protein concentrations by using small angle X-ray scattering. Furthermore, we clarified that the subunit interaction is quite important for the total structural stability. Less