Peptide conformation and supramolecular organization in amylin fibrils: Constraints from solid-state NMR
Peptide conformation and supramolecular organization in amylin fibrils: Constraints from solid-state NMR
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DOI：
10.1021/bi701427q
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发表时间：
2007-11-27
期刊：
影响因子：
2.9
通讯作者：
Tycko, Robert
中科院分区：
文献类型：
--
作者：
Luca, Sorin;Yau, Wai-Ming;Tycko, Robert
37 残基胰淀素肽，也称为胰岛淀粉样多肽，形成原纤维，是 2 型糖尿病患者胰腺中形成的淀粉样蛋白的主要肽或蛋白质成分。胰岛淀粉样蛋白还很容易在体外形成淀粉样原纤维，这些原纤维在典型的实验条件下具有高度多态性。我们描述了一种制备合成胰淀素原纤维的方案，该原纤维在电子显微镜和原子力显微镜图像中表现出单一的主要形态，我们称之为条纹带。对一系列同位素标记样品进行的固态核磁共振 (NMR) 测量表明，条纹带内存在单一分子结构。我们使用扫描透射电子显微镜和几种一维和二维固态核磁共振技术来获得对这些胰岛淀粉样多肽原纤维中肽构象和超分子结构的约束，并推导出与实验数据一致的分子结构模型。胰淀素条纹带的基本结构单元，我们称之为原丝，包含四层平行的β-折叠层，由两层对称的胰淀素分子形成。条纹带中胰淀素原丝的分子结构与淀粉样原纤维中的原丝非常相似，具有与阿尔茨海默病相关的 40 个残基 β-淀粉样肽形成的相似形态。
The 37-residue amylin peptide, also known as islet amyloid polypeptide, forms fibrils that are the main peptide or protein component of amyloid that develops in the pancreas of type 2 diabetes patients. Amylin also readily forms amyloid fibrils in vitro that are highly polymorphic under typical experimental conditions. We describe a protocol for the preparation of synthetic amylin fibrils that exhibit a single predominant morphology, which we call a striated ribbon, in electron microscopy and atomic force microscopy images. Solid-state nuclear magnetic resonance (NMR) measurements on a series of isotopically labeled samples indicate a single molecular structure within the striated ribbons. We use scanning transmission electron microscopy and several types of one- and two-dimensional solid-state NMR techniques to obtain constraints on the peptide conformation and supramolecular structure in these amylin fibrils and to derive molecular structural models that are consistent with the experimental data. The basic structural unit in amylin striated ribbons, which we call the protofilament, contains four layers of parallel beta-sheets, formed by two symmetric layers of amylin molecules. The molecular structure of amylin protofilaments in striated ribbons closely resembles the protofilament in amyloid fibrils with a similar morphology formed by the 40-residue beta-amyloid peptide that is associated with Alzheimer's disease.