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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0 SS的淀粉样蛋白原纤化反应以这样的方式依赖于盐浓度和pH，即蛋白质正电荷的屏蔽促进原纤化。它符合成核-伸长反应图式，存在临界单体浓度。核的大小随不同的盐浓度和pH值而变化。从纤维状聚合物的末端单体单元的解离速率常数的绝对值得到使用的理论方程推导出的目的，通过考虑到纤维的长度分布。存在一个大的，多达三个数量级，在原纤化率的变化之间的四个1 SS的变体，它们共同具有各种三级约束和分子内结构，这意味着N-和C-末端区域应该是彼此分开的有效的原纤维形成。用小角X射线散射法测定了纤维直径， ...更多信息 nt在1 SS变体之间显著不同。此外，4SS分子的原纤维在形态和直径上与0 SS和1 SS的原纤维显著不同。因此，纤维化的反应速率和机制受到蛋白质内结构的种类和数量的强烈调节.通过使用NMR检测的H/D交换，鉴定了由于结构形成而被保护免于交换的肽区域：在0 SS原纤维中，它们是四个肽区域，每个跨越7 - 9个残基，其与高疏水性和β-倾向性区域一致。而两种1 SS种类的原纤维显示出与0 SS原纤维相似的受保护区域，其它1 SS种的原纤维显示出不同的保护区。此外，这些受保护的区域完全不同于WT溶菌酶原纤维的核心区域。因此，蛋白质内结构的种类和数量调节参与淀粉样蛋白纤维化的成核和延伸的肽区域。少