Molecular study on large conformational changes of protein that relates biofunction and diseases

本论文对与生物功能和疾病密切相关的蛋白质稳定性进行了详细的研究，包括蛋白质整体构象变化和分子伴侣的作用机制，取得了以下研究成果：1.寡聚蛋白的结构和稳定性研究：我们测定了热稳定性淀粉酶的X-射线晶体结构，并阐明了该酶的热稳定性机制和活性中心结构。另一方面，我们利用小角X射线散射研究了大肠杆菌辅伴侣蛋白GroES七聚体在高蛋白浓度下的溶液结构和分子去折叠机制。2.蛋白质构象变化和淀粉样纤维形成的研究：我们发现，与疾病无关的寡聚蛋白GroES在一定条件下形成典型的淀粉样纤维，并从分子紧密性的角度阐明了纤维的形成机理。此外，我们还研究了帕金森病的致病蛋白α-突触核蛋白的纤维形成机制，证明了在其他不同蛋白质纤维的预形成种子存在下，α-突触核蛋白的淀粉样纤维形成显著加快。3.分子伴侣的结构与功能研究：我们对大肠杆菌中的Ⅰ类伴侣蛋白GroEL和超耐热菌中的Ⅱ类伴侣蛋白进行了详细的结构和功能关系研究。我们发现GroEL的结构域运动对功能非常重要，并且钴和锰离子是II组伴侣蛋白的核苷酸水解活性和底物重折叠功能的新因素。此外，我们还研究了斑马鱼热休克蛋白60的功能，阐明了热休克蛋白60是在再生过程中芽基形成和维持所必需的。

Studies on protein stability including global conformational changes and functional mechanism of molecular chaperone, which are closely related to biofunction and diseases, were performed in detail and following results were obtained.1.Study on structure and stability of oligomeric protein : We have determined 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.2.Study on conformational changes and amyloid fibril formation of protein : We have found that oligomeric protein GroES, that is a non-related protein to disease, formed a typical amyloid fibril under a certain condition, and elucidated the fibril formation mechanism in terms of molecular compactness. Furthermore, we studied fibril formation mechanism of α-synuclein, a causative protein of Parkinson 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 function of molecular chaperone : 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. 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. Furthermore, we have investigated function of zebrafish Hsp60, and elucidated that Hsp60 is required for blastema formation and maintenance during regeneration.