title: Destabilization of transthyretin by pathogenic mutations in the DE loop.
abstract: Transthyretin single-amino-acid variants are responsible for familial amyloidotic polyneuropathy, in which transthyretin variants accumulate extracellularly in the form of fibrillar aggregates. We studied the structural stabilities of four transthyretin variants (L58H, L58R, T59K, and E61K), in which a positively charged amino acid is introduced in a loop region between the D- and E-strands. In addition to being located in the DE-loop, L58 and T59 are involved in the core of the transthyretin monomer. The L58H, L58R, and T59K substitutions destabilized transthyretin more than the E61K mutation did, indicating that transthyretin is substantially destabilized by the substitution of residues located in both the DE-loop and the monomer core. By utilizing hydrogen-deuterium exchange and nuclear magnetic resonance, we demonstrated that residues in the G-strand and the loop between the A- and B-strands were destabilized by these pathogenic mutations in the DE loop. At the quaternary structural level, the DE-loop mutations destabilized the dimer-dimer contact area, which may lead to transient dissociation into a dimer. Our results suggest that the destabilization of the dimer-dimer interface and the monomer core is important for the amyloidogenesis of transthyretin.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Mineyuki
authors.initials: M
authors.lastname: Mizuguchi
authors.forename: Takahide
authors.initials: T
authors.lastname: Kouno
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Aizawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Demura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mori
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shinoda
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kawano
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003903:Deuterium; D019281:Dimerization; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics; D014644:Genetic Variation; D006801:Humans; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009154:Mutation; D011228:Prealbumin / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D000682:Amyloid; D011228:Prealbumin; D011994:Recombinant Proteins; D006859:Hydrogen; D003903:Deuterium