Experimental constraints on quaternary structure in Alzheimer's β-amyloid fibrils
Experimental constraints on quaternary structure in Alzheimer's β-amyloid fibrils
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DOI：
10.1021/bi051952q
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发表时间：
2006-01-17
期刊：
影响因子：
2.9
通讯作者：
Tycko, R
中科院分区：
文献类型：
--
作者：
Petkova, AT;Yau, WM;Tycko, R
我们描述了固态核磁共振（NMR）测量与阿尔茨海默氏病（A β（1-40））相关的40-残基β-淀粉样肽形成的原纤维，限制的身份和对称性之间的接触登记，平行β-片原纤维。我们将这些接触称为内部和外部四元接触，这取决于它们是在单个分子层内还是在分子层之间。数据包括（1）二维C-13-C-13 NMR谱，其表明L17和F19的侧链与132、L34和V36的侧链之间的内部四级接触，以及131和G37的侧链之间的外部四级接触;（2）二维N-15-C-13 NMR光谱，其表明M35的侧链与G33处的肽骨架之间的外部四级接触;（3）D23的侧链羧酸酯基团和K28的侧链胺基之间的磁偶极-偶极偶联的测量，其指示盐桥相互作用。同位素稀释实验使我们能够区分分子内和分子间的接触。在这些数据和先前确定的结构约束的基础上，从固态NMR和电子显微镜，我们构建完整的分子模型，使用约束的分子动力学模拟和约束的能量最小化。这些模型适用于在温和搅拌下生长的A β（1-40）原纤维。我们还提出了在A β（1-40）原纤维生长没有搅拌，这是形态上不同的内部四级接触的证据。
We describe solid-state nuclear magnetic resonance (NMR) measurements on fibrils formed by the 40-residue beta-amyloid peptide associated with Alzheimer's disease (A beta(1-40)) that place constraints on the identity and symmetry of contacts between in-register, parallel beta-sheets in the fibrils. We refer to these contacts as internal and external quaternary contacts, depending on whether they are within a single molecular layer or between molecular layers. The data include (1) two-dimensional C-13-C-13 NMR spectra that indicate internal quaternary contacts between side chains of L17 and F19 and side chains of 132, L34, and V36, as well as external quaternary contacts between side chains of 131 and G37; (2) two-dimensional N-15-C-13 NMR spectra that indicate external quaternary contacts between the side chain of M35 and the peptide backbone at G33; (3) measurements of magnetic dipole-dipole couplings between the side chain carboxylate group of D23 and the side chain amine group of K28 that indicate salt bridge interactions. Isotopic dilution experiments allow us to make distinctions between intramolecular and intermolecular contacts. On the basis of these data and previously determined structural constraints from solid-state NMR and electron microscopy, we construct full molecular models using restrained molecular dynamics simulations and restrained energy minimization. These models apply to A beta(1-40) fibrils grown with gentle agitation. We also present evidence for different internal quaternary contacts in A beta(1-40) fibrils grown without agitation, which are morphologically distinct.