3D structure of amyloid protofilaments of β2-microglobulin fragment probed by solid-state NMR
3D structure of amyloid protofilaments of β2-microglobulin fragment probed by solid-state NMR
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DOI：
10.1073/pnas.0607180103
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发表时间：
2006-11-28
影响因子：
11.1
通讯作者：
Goto, Yuji
中科院分区：
文献类型：
--
作者：
Iwata, Kentaro;Fujiwara, Toshimichi;Goto, Yuji
了解淀粉样原纤维的结构和形成，蛋白质和肽的丝状聚集体，对于预防由其沉积引起的疾病至关重要，此外，对于进一步了解蛋白质折叠和错误折叠的机制也至关重要。我们结合了固态NMR、X射线纤维衍射和原子力显微镜来揭示由β 2-微球蛋白的22个残基K3肽（Ser（20）-LyS（41））形成的淀粉样蛋白原纤维样纤维的3D结构，β 2-微球蛋白是一种负责透析相关淀粉样变性的蛋白质。虽然均匀的C-13，N-15标记的样品用于NMR测量，我们可以获得的3D结构的原纤维的基础上，大量的结构约束。K3原纤维的构象被发现是一个β-链-环-β-链，每个K3分子以平行和交错的方式堆叠。有人建议，纤维状构象是稳定的分子间的相互作用，而不是通过分子内的疏水包装中看到的球状蛋白质。结合全长蛋白质的热力学研究，原纤维的形成可能需要分子间表面上的侧链紧密地堆积在相邻单体的侧链上。通过揭示β（2）-微球蛋白原纤维样纤维的结构，这项工作代表了通过固态NMR分析淀粉样纤维的技术进展。
Understanding the structure and formation of amyloid fibrils, the filamentous aggregates of proteins and peptides, is crucial in preventing diseases caused by their deposition and, moreover, for obtaining further insight into the mechanism of protein folding and misfolding. We have combined solid-state NMR, x-ray fiber diffraction, and atomic force microscopy to reveal the 3D structure of amyloid protofilament-like fibrils formed by a 22-residue K3 peptide (Ser(20)-LyS(41)) of beta(2)-Microglobulin, a protein responsible for dialysis-related amyloidosis. Although a uniformly C-13,N-15-labeled sample was used for the NMR measurements, we could obtain the 3D structure of the fibrils on the basis of a large number of structural constraints. The conformation of K3 fibrils was found to be a beta-strand-loop-beta-strand with each K3 molecule stacked in a parallel and staggered manner. It is suggested that the fibrillar conformation is stabilized by intermolecular interactions, rather than by intramolecular hydrophobic packing as seen in globular proteins. Together with thermodynamic studies of the full-length protein, formation of the fibrils is likely to require side chains on the intermolecular surface to pack tightly against those of adjacent monomers. By revealing the structure of beta(2)-microglobulin protofilament-like fibrils, this work represents technical progress in analyzing amyloid fibrils in general through solid-state NMR.