Interaction of Thioflavin T with amyloid fibrils of apolipoprotein A-I N-terminal fragment: Resonance energy transfer study

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• 作者：Mykhailo Girych ; Galyna Gorbenko ; Valeriya Trusova ; Emi Adachi ; Chiharu Mizuguchi ; Kohjiro Nagao ; Hiroyuki Kawashima ; Kenichi Akaji ; Sissel Lund-Katz ; Michael C. Phillips ; Hiroyuki Saito
• 关键词：Amyloid fibrils ; ApoA-I N-terminal fragment ; Thioflavin T ; Fö ; rster resonance energy transfer
• 刊名：Journal of Structural Biology
• 出版年：January, 2014
• 年：2014
• 卷：185
• 期：1
• 页码：116-124
• 全文大小：1764 K

文摘

Apolipoprotein A-I is amenable to a number of specific mutations associated with hereditary systemic amyloidoses. Amyloidogenic properties of apoA-I are determined mainly by its N-terminal fragment. In the present study F枚rster resonance energy transfer between tryptophan as a donor and Thioflavin T as an acceptor was employed to obtain structural information on the amyloid fibrils formed by apoA-I variant 1-83/G26R/W@8. Analysis of the dye-fibril binding data provided evidence for the presence of two types of ThT binding sites with similar stoichiometries (bound dye to monomeric protein molar ratio 鈭?0), but different association constants (鈭? and 0.1 渭M^鈭?) and ThT quantum yields in fibril-associated state (0.08 and 0.05, respectively). A 尾-strand-loop-尾-strand structural model of 1-83/G26R/W@8 apoA-I fibrils has been proposed, with potential ThT binding sites located in the solvent-exposed grooves of the N-terminal 尾-sheet layer. Reasoning from the expanded FRET analysis allowing for heterogeneity of ThT binding centers and fibril polymorphism, the most probable locations of high- and low-affinity ThT binding sites were attributed to the grooves T16_Y18 and D20_L22, respectively.