Atomic Details of the Interactions of Glycosaminoglycans with Amyloid-β Fibrils

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• 作者：Katie L. Stewart ; Eleri Hughes ; Edwin A. Yates ; Geoffrey R. Akien ; Teng-Yi Huang ; Marcelo A. Lima ; Timothy R. Rudd ; Marco Guerrini ; Shang-Cheng Hung ; Sheena E. Radford ; David A. Middleton
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：July 13, 2016
• 年：2016
• 卷：138
• 期：27
• 页码：8328-8331
• 全文大小：341K
• 年卷期：0
• ISSN：1520-5126

文摘

The amyloid plaques associated with Alzheimer’s disease (AD) comprise fibrillar amyloid-β (Aβ) peptides as well as non-protein factors including glycosaminoglycan (GAG) polysaccharides. GAGs affect the kinetics and pathway of Aβ self-assembly and can impede fibril clearance; thus, they may be accessory molecules in AD. Here we report the first high-resolution details of GAG–Aβ fibril interactions from the perspective of the saccharide. Binding analysis indicated that the GAG proxy heparin has a remarkably high affinity for Aβ fibrils with 3-fold cross-sectional symmetry (3Q). Chemical synthesis of a uniformly ¹³C-labeled octasaccharide heparin analogue enabled magic-angle spinning solid-state NMR of the GAG bound to 3Q fibrils, and measurements of dynamics revealed a tight complex in which all saccharide residues are restrained without undergoing substantial conformational changes. Intramolecular ¹³C–¹⁵N dipolar dephasing is consistent with close (<5 Å) contact between GAG anomeric position(s) and one or more histidine residues in the fibrils. These data provide a detailed model for the interaction between 3Q-seeded Aβ40 fibrils and a major non-protein component of AD plaques, and they reveal that GAG–amyloid interactions display a range of affinities that critically depend on the precise details of the fibril architecture.