Capturing intermediate structures of Alzheimer's β-amyloid, Aβ(1-40), by solid-state NMR spectroscopy
Capturing intermediate structures of Alzheimer's β-amyloid, Aβ(1-40), by solid-state NMR spectroscopy
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DOI：
10.1021/ja054039l
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发表时间：
2005-10-05
影响因子：
15
通讯作者：
Ishii, Y
中科院分区：
文献类型：
--
作者：
Chimon, S;Ishii, Y
可扩散的淀粉样蛋白中间体的分子结构，通常在淀粉样蛋白质错误折叠成原纤维中观察到，已经引起了广泛的兴趣，因为中间体可能是负责淀粉样疾病如阿尔茨海默病（AD）的有效神经毒素，并且因为中间体结构提供了定义错误折叠途径的实验基础。然而，由于系统的内在不稳定性和非结晶性，传统的方法，如X-射线晶体学和溶液NMR已经无法阐明淀粉样蛋白中间体的分子水平结构。我们提出了一种使用固态NMR（SSNMR）的新方法，该方法允许首次对40个残基的阿尔茨海默氏β淀粉样肽Aβ（1−40）原纤维形成中的中间物质进行位点分辨结构测量。在这种方法中，我们结合检测构象和形态变化的荧光光谱和电子显微镜和定量结构检查的冷冻捕获的中间体SSNMR。这些结果提供了初步证据，即在Aβ（1−40）形成原纤维之前，存在一个直径为15−30 nm的球形淀粉样蛋白中间体，并且该中间体在C末端和疏水核心区域涉及有序的β折叠。本文提出的基于SSNMR的方法可以应用于不同淀粉样蛋白的中间物种。
Molecular structures of diffusible amyloid intermediates, commonly observed in misfolding of amyloid proteins into fibrils, have attracted broad interest because the intermediates may be potent neurotoxins responsible for amyloid diseases such as Alzheimer's disease (AD) and because the intermediate structures provide an experimental basis for defining the misfolding pathway. However, owing to the intrinsically unstable and noncrystalline nature of the systems, traditional approaches such as X-ray crystallography and solution NMR have been ineffective for elucidating molecular-level structures of the amyloid intermediates. We present a novel approach using solid-state NMR (SSNMR) that permitted the first site-resolved structural measurement of an intermediate species in fibril formation for a 40-residue Alzheimer's β-amyloid peptide, Aβ(1−40). In this approach, we combined detection of conformation and morphology changes by fluorescence spectroscopy and electron microscopy and quantitative structural examination for freeze-trapped intermediates by SSNMR. The results provide the initial evidence that a spherical amyloid intermediate of 15−30 nm in diameter exists prior to fibril formation of Aβ(1−40) and that the intermediate involves well-ordered β-sheets in the C-terminal and hydrophobic core regions. The SSNMR-based approach presented here could be applied to intermediate species of diverse amyloid proteins.