Solid-state NMR study of amyloid nanocrystals and fibrils formed by the peptide GNNQQNY from yeast prion protein Sup35p
Solid-state NMR study of amyloid nanocrystals and fibrils formed by the peptide GNNQQNY from yeast prion protein Sup35p
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DOI：
10.1021/ja068633m
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发表时间：
2007-04-25
影响因子：
15
通讯作者：
Griffin, Robert G.
中科院分区：
文献类型：
--
作者：
van der Wel, Patrick C. A.;Lewandowski, Jozef R.;Griffin, Robert G.
Sup35p是在酵母中发现的朊病毒蛋白，其含有朊病毒形成结构域，其特征在于富含Gln、Asn、Tyr和Gly氨基酸残基的重复序列。肽GNNQQNY（7 - 13）是发现以类似于蛋白质本身的方式形成淀粉样纤维的该结构域的最短片段之一。在水中溶解后，GNNQQNY显示出浓度依赖性的多晶型，在低浓度下形成单斜晶体和正交晶体，在较高浓度下形成淀粉样蛋白原纤维。我们制备了两种空间群的纳米晶体以及可重复地包含三种（共存）结构形式的原纤维样品，并用魔角自旋（MAS）固态核磁共振检查了样品。C-13和N-15 MAS光谱的纳米晶体和原纤维揭示窄共振指示高水平的微观样品的均匀性，允许所有五个物种的共振分配。我们观察到的三种主要形式的原纤维，这是由三个不同的，自洽的相关NMR信号的存在下表示的化学位移的变化。类似地，单斜晶和斜方晶晶体表现出彼此不同且与原纤维不同的化学位移。总的来说，化学位移数据表明，肽在晶体和原纤维中呈现五种构象，这些构象以微妙但不同的方式彼此不同。这包括芳族Tyr环的流动性的变化。这些数据还表明，由肽假定的各种结构可能与在单斜晶体中观察到的"空间拉链"相关。
Sup35p is a prion protein found in yeast that contains a prion-forming domain characterized by a repetitive sequence rich in Gln, Asn, Tyr, and Gly amino acid residues. The peptide GNNQQNY(7-13) is one of the shortest segments of this domain found to form amyloid fibrils, in a fashion similar to the protein itself. Upon dissolution in water, GNNQQNY displays a concentration-dependent polymorphism, forming monoclinic and orthorhombic crystals at low concentrations and amyloid fibrils at higher concentrations. We prepared nanocrystals of both space groups as well as fibril samples that reproducibly contain three (coexisting) structural forms and examined the specimens with magic angle spinning (MAS) solid-state nuclear magnetic resonance. C-13 and N-15 MAS spectra of both nanocrystals and fibrils reveal narrow resonances indicative of a high level of microscopic sample homogeneity that permitted resonance assignments of all five species. We observed variations in chemical shift among the three dominant forms of the fibrils which were indicated by the presence of three distinct, self-consistent sets of correlated NMR signals. Similarly, the monoclinic and orthorhombic crystals exhibit chemical shifts that differ from one another and from the fibrils. Collectively, the chemical shift data suggest that the peptide assumes five conformations in the crystals and fibrils that differ from one another in subtle but distinct ways. This includes variations in the mobility of the aromatic Tyr ring. The data also suggest that various structures assumed by the peptide may be correlated to the "steric zipper" observed in the monoclinic crystals.