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

Mykhailo Girych, Galyna Gorbenko, Valeriya Trusova, Emi Adachi, Chiharu Mizuguchi, Kohjiro Nagao, Hiroyuki Kawashima, Kenichi Akaji, Sissel Lund-Katz, Michael C. Phillips, Hiroyuki Saito

Research output: Contribution to journalArticleScientificpeer-review

Abstract

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 Förster 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 ∼10), but different association constants (∼6 and 0.1 μM−1) and ThT quantum yields in fibril-associated state (0.08 and 0.05, respectively). A β-strand–loop–β-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 β-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.
Original languageEnglish
Pages (from-to)116-124
JournalJournal of Structural Biology
Volume185
Issue number1
DOIs
Publication statusPublished - Jan 2014
MoE publication typeA1 Journal article-refereed

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