Distinct effects of Cu^2＋-binding on oligomerization of human and rabbit prion proteins  

作　　者：Kejiang Lin Ziyao Yu Yuanhui Yu Xinli Liao Pei Huang Chenyun Guo Donghai Lin 

机构地区：[1]Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 21009, China [2]High-field NMR Research Center, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China

出　　处：《Acta Biochimica et Biophysica Sinica》2015年第10期842-850,共9页生物化学与生物物理学报（英文版）

基　　金：This work was supported by the grants from the National Natural Science Foundation of China （Nos. 31170717, 31470034, and 31270777）.

摘　　要：The cellular prion protein （PrP^C） is a kind of cell-surface Cu^2＋-binding glycoprotein. The oligomerization of PrP^C is highly related to transmissible spongiform encephalopathies （TSEs）. Cu^2＋ plays a vital role in the oligomerization of PrP^C, and participates in the pathogenic process of TSE diseases. It is expected that Cu^2＋-binding has different effects on the oligomerization of TSE-sensitive human PrP^C （HuPrP^C） and TSE-resistant rabbit PrP^C （RaPrp^C）. However, the details of the distinct effects remain unclear. In the present study, we measured the interactions of Cu^2＋ with HuPrP^C （91-230） and RaPrP^C （91-228） by isothermal titration calorimetry, and compared the effects of Cu^2＋-binding on the oligomerization of both PrPs. The measured dissociation constants （Kd） of Cu^2＋ were 11.1 ± 2.1 μM for HuPrP^C and 21.1 ±3.1 μM for RaPrP^C. Cu^2＋-binding promoted the oligomerization of HuPrP^C more significantly than that of RaPrP^C. The far-ultraviolet circular dichroism spectroscopy experiments showed that Cu^2＋-binding induced more significant secondary structure change and increased more β-sheet content for HuPrP^C compared with RaPrP^C. Moreover, the urea-induced unfolding transition experiments indicated that Cu^2＋-binding decreased the conformational stability of HuPrP^C more distinctly than that of RaPrP^C. These results suggest that RaPrPc possesses a low susceptibility to Cu^2＋, potentially weakening the risk of Cu^2＋-induced TSE diseases. Our work sheds light on the Cu^2＋-promoted oligomerization of PrP^C, and may be helpful for further understanding the TSE- resistance of rabbits.The cellular prion protein （PrP^C） is a kind of cell-surface Cu^2＋-binding glycoprotein. The oligomerization of PrP^C is highly related to transmissible spongiform encephalopathies （TSEs）. Cu^2＋ plays a vital role in the oligomerization of PrP^C, and participates in the pathogenic process of TSE diseases. It is expected that Cu^2＋-binding has different effects on the oligomerization of TSE-sensitive human PrP^C （HuPrP^C） and TSE-resistant rabbit PrP^C （RaPrp^C）. However, the details of the distinct effects remain unclear. In the present study, we measured the interactions of Cu^2＋ with HuPrP^C （91-230） and RaPrP^C （91-228） by isothermal titration calorimetry, and compared the effects of Cu^2＋-binding on the oligomerization of both PrPs. The measured dissociation constants （Kd） of Cu^2＋ were 11.1 ± 2.1 μM for HuPrP^C and 21.1 ±3.1 μM for RaPrP^C. Cu^2＋-binding promoted the oligomerization of HuPrP^C more significantly than that of RaPrP^C. The far-ultraviolet circular dichroism spectroscopy experiments showed that Cu^2＋-binding induced more significant secondary structure change and increased more β-sheet content for HuPrP^C compared with RaPrP^C. Moreover, the urea-induced unfolding transition experiments indicated that Cu^2＋-binding decreased the conformational stability of HuPrP^C more distinctly than that of RaPrP^C. These results suggest that RaPrPc possesses a low susceptibility to Cu^2＋, potentially weakening the risk of Cu^2＋-induced TSE diseases. Our work sheds light on the Cu^2＋-promoted oligomerization of PrP^C, and may be helpful for further understanding the TSE- resistance of rabbits.

关 键 词：Cu^2＋ prion oligomerization AFFINITY conformational stability TSE-resistance 

分 类 号：S852.659.7[农业科学—基础兽医学] S855.3[农业科学—兽医学]