Interaction of thioflavin T with amyloid fibrils of apolipoprotein A-I N-terminal fragment: resonance energy transfer study.
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 0.1μM(-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.
Department of Nuclear and Medical Physics, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkov 61077, Ukraine. Electronic address: girichms@gmail.com.
Mykhailo
M
Girych
Department of Nuclear and Medical Physics, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkov 61077, Ukraine.
Galyna
G
Gorbenko
Department of Nuclear and Medical Physics, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkov 61077, Ukraine.
Valeriya
V
Trusova
Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
Emi
E
Adachi
Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
Chiharu
C
Mizuguchi
Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
Kohjiro
K
Nagao
Department of Medicinal Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan.
Hiroyuki
H
Kawashima
Department of Medicinal Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan.
Kenichi
K
Akaji
Lipid Research Group, Gastroenterology, Hepatology and Nutrition Division, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104-4318, United States.
Sissel
S
Lund-Katz
Lipid Research Group, Gastroenterology, Hepatology and Nutrition Division, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104-4318, United States.
Michael C
MC
Phillips
Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
Hiroyuki
H
Saito
D000682:Amyloid / Q000737:chemistry*; D016632:Apolipoprotein A-I / Q000737:chemistry*; D052160:Benzothiazoles; D001665:Binding Sites; D004735:Energy Transfer; D006801:Humans; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D013844:Thiazoles / Q000737:chemistry*
D000682:Amyloid; D016632:Apolipoprotein A-I; D052160:Benzothiazoles; D013844:Thiazoles; C009462:thioflavin T
Amyloid fibrils; ApoA-I N-terminal fragment; Förster resonance energy transfer; Thioflavin T