Molecular mechanism of copper reduction by the octapeptide repeat region of prion protein

朊病毒蛋白八肽重复区还原铜的分子机制

• 批准号: 15590037
• 负责人: MIURA Takashi
• 金额: $ 2.24万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15590037/
• 关键词: prion protein; copper; reduction; metal complex; Raman spectroscopy; copper transporter; 分子構造

The physiological function of the prion protein (PrP) remains enigmatic in spite of its established involvement in the pathogenesis of spongiform encephalopathies. PrP is a glycolipid-anchored membrane protein, which constitutively recycles between the cell surface and an endosomal compartment. The N-terminal region of PrP contains a four tandem repeat (OP4) of the octapeptide PHGGGWGQ (OP) that binds and reduces Cu(II) ions. We have examined the kinetic properties of the OP4-mediated Cu(II) reduction and found that OP4 exhibits the highest reduction activity around pH 6.5, close to the pH in early endosomes. All four OP units and at least one tryptophan side chain are essential for Cu(II) reduction. The reaction is described by an uncompetitive substrate inhibition mechanism involving a 1:1 Cu(II)-OP4 active intermediate. Structural analysis by Raman spectroscopy has revealed that the Cu(II) ion is coordinated by four histidine Nτ atoms in the active intermediate and the feasibility of formation of this intermediate correlates with the Cu(II) reduction over a pH range from 5.0 to 8.2. Molecular mechanics calculations suggest that two tryptophan residues of OP4 are located near the Cu(II) site, being consistent with the importance of redox-active tryptophan in the Cu(II) reduction. PrP has been proposed to capture Cu(II) ions in the extracellular space and release them in the endosome. The results of this study strongly suggest that PrP also plays a role in the reduction of captured Cu(II) ions prior to their transfer to Cu(I)-specific intracellular copper trafficking proteins.

尽管已确定参与了赞助型脑病的发病机理，但Prion蛋白（PRP）的身体功能仍然神秘。 PRP是一种糖脂锚定的膜蛋白，在细胞表面和内体室之间进行组成式回收。 PRP的N末端区域包含四个串联重复（OP4）的八肽PHGGGWGQ（OP），该重复（OP）结合并减少了Cu（II）离子。我们已经检查了OP4介导的Cu（II）还原的动力学特性，并发现OP4在早期内体的pH值接近pH值附近表现出最高的还原活性。所有四个OP单元和至少一个色氨酸侧链对于Cu（II）还原至关重要。反应是通过涉及1：1 Cu（ii）-OP4活性中间体的非竞争性底物抑制机制来描述的。拉曼光谱法的结构分析表明，在活性中间体中，Cu（II）离子由四个组氨酸Nτ原子协调，并且该中间体形成的可行性与pH范围为5.0至8.2的pH范围内的CU（II）降低相关。分子力学计算表明，OP4的两个色氨酸保留位于Cu（II）位置附近，与Cu（II）还原中氧化还原活性色氨酸的重要性一致。已提出PRP捕获细胞外空间中的Cu（II）离子并将其释放到内体中。这项研究的结果强烈表明，PRP在将其转移到Cu（I）特异性细胞内铜运输蛋白之前，在捕获的Cu（II）离子的还原（II）离子中起作用。

项目成果

Takashi Miura et al.: "Copper Selectively Triggers β-Sheet Assembly of an N-Terminally Truncated Amyloid β-Peptide Beginning with Glu3"J.Inorg.Biochem. 98. 10-14 (2004)

Takashi Miura 等人：“铜选择性触发以 Glu3 开头的 N 末端截短的淀粉样 β-肽的 β-片层组装”J.Inorg.Biochem. 98. 10-14 (2004)