title: Decreased amyloidogenicity caused by mutational modulation of surface properties of the immunoglobulin light chain BRE variable domain.
abstract: Amyloid formation by immunoglobulin light chain (LC) proteins is associated with amyloid light chain (AL) amyloidosis. Destabilization of the native state of the variable domain of the LC (VL) is known to be one of the critical factors in promoting the formation of amyloid fibrils. However, determining the key residues involved in this destabilization remains challenging, because of the existence of a number of intrinsic sequence variations within VL. In this study, we identified the key residues for destabilization of the native state of amyloidogenic VL in the LC of BRE by analyzing the stability of chimeric mutants of BRE and REI VL; the latter immunoglobulin is not associated with AL amyloidosis. The results suggest that the surface-exposed residues N45 and D50 are the key residues in the destabilization of the native state of BRE VL. Point mutations at the corresponding residues in REI VL (K45N, E50D, and K45N/E50D) destabilized the native state and increased amyloidogenicity. However, the reverse mutations in BRE VL (N45K, D50E, and N45K/D50E) re-established the native state and decreased amyloidogenicity. Thus, analyses using chimeras and point mutants successfully elucidated the key residues involved in BRE VL destabilization and increased amyloidogenic propensity. These results also suggest that the modulation of surface properties of wild-type VL may improve their stability and prevent the formation of amyloid fibrils.
authors: Division of Structural Biology, Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Kobe University , 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors: Yuta
authors: Y
authors: Kobayashi
authors: Hirotaka
authors: H
authors: Tsutsumi
authors: Tetsuyuki
authors: T
authors: Abe
authors: Kyohei
authors: K
authors: Ikeda
authors: Yuki
authors: Y
authors: Tashiro
authors: Satoru
authors: S
authors: Unzai
authors: Hironari
authors: H
authors: Kamikubo
authors: Mikio
authors: M
authors: Kataoka
authors: Hidekazu
authors: H
authors: Hiroaki
authors: Daizo
authors: D
authors: Hamada
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000682:Amyloid / Q000378:metabolism*; D000686:Amyloidosis / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011487:Protein Conformation; D055550:Protein Stability; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
chemical_list: D000682:Amyloid; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D050505:Mutant Proteins; D011994:Recombinant Proteins