Clarification of amyloid fibrillation mechanism by modulating intraproteinaceous structure

通过调节蛋白质内结构阐明淀粉样纤维颤动机制

基本信息

批准号：
17570132
负责人：
TACHIBANA Hideki
金额：
$ 1.66万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17570132/
关键词：
Protein Amyloid Disulfide Lysozyme Nucleation beta-structure Hydrogen deuterium-exchange

项目摘要

1. The amyloid-fibrillation reaction of a lysozyme all-disulfide-deficient variant, 0SS, depends on salt-concentration and pH in such a way that the screening of the protein positive charge facilitates the fibrillation. It conforms to a nucleation-elongation reaction scheme and there exists critical monomer concentrations. A nucleus size varies with varying salt-concentration and pH. The absolute value of the dissociation rate constant of monomeric unit from the end of fibrillar polymer was obtained using a theoretical equation derived for the purpose by taking the length-distribution of fibrils into account. There exists a large, as much as three-orders of magnitude, variation in the fibrillation rate among the four 1SS variants, which collectively have a various kinds of tertiary constraints and intramolecular structures, implying that the N- and C-terminal regions should be apart from each other for efficient protofibril formation. The fibril diameter as obtained from SAXS measureme … More nt differs significantly among the 1SS variants. Moreover, the fibril of a 4SS molecule differs markedly in both morphology and diameter from the fibrils of 0SS and 1SS. Thus, the reaction rate and mechanism of fibrillation are strongly modulated by the kinds and amount of intraprotein structures.2. By using NMR-detected H/D-exchange the peptide regions protected from the exchange by virtue of structure formation were identified : in the 0SS fibril they are four peptide regions, each spanning seven to nine residues, which coincide with the regions of both high hydrophobicity and beta-propensity While the fibrils of two 1SS species show protected regions similar to those of 0SS fibril, the fibrils of the other 1SS species show different protected regions. Moreover, these protected regions altogether differ from the core region of WT lysozyme fibril. Thus, the kinds and amount of intraprotein structure modulate the peptide regions involved in nucleation and elongation of amyloid fibrillation. Less

1. 溶菌酶全二硫键缺陷变体 0SS 的淀粉样原纤维化反应取决于盐浓度和 pH 值，因此蛋白质正电荷的筛选有利于原纤维化，这符合成核延伸反应。方案中存在临界单体浓度随盐浓度和pH的变化而变化的单体单元从末端的解离速率常数的绝对值。原纤维聚合物的原纤化率是通过考虑原纤维的长度分布而导出的理论方程获得的。四种 1SS 变体之间的原纤化率存在很大的差异，多达三个数量级。共同具有各种三级约束和分子内结构，这意味着 N 端和 C 端区域应该彼此分开，以有效形成原纤维。 SAXS 测量结果在 1SS 变体之间存在显着差异，此外，4SS 分子的原纤维在形态和直径上与 0SS 和 1SS 的原纤维显着不同，因此，原纤维的反应速率和机制受其种类和结构的影响。 2. 通过使用 NMR 检测的 H/D 交换，鉴定出由于结构形成而免受交换的肽区域：在 0SS 中原纤维它们是四个肽区域，每个肽区域跨越七到九个残基，与高疏水性和β倾向的区域一致，而两个1SS物种的原纤维显示出与0SS原纤维、另一个1SS原纤维相似的受保护区域此外，这些受保护区域总体上与WT溶菌酶原纤维的核心区域不同，因此，蛋白质内结构的种类和数量调节涉及的肽区域。淀粉样原纤维的成核和伸长较少。