title: The effect of amino acid substitution in the imperfect repeat sequences of alpha-synuclein on fibrillation.
abstract: Human alpha-synuclein is the causative protein of several neurodegenerative diseases, such as Parkinson's disease (PD) and dementia with Lewy Bodies (DLB). The N-terminal half of alpha-synuclein contains seven imperfect repeat sequences. One of the PD/DLB-causing point mutations, E46K, has been reported in the imperfect repeat sequences of alpha-synuclein, and is prone to form amyloid fibrils. The presence of seven imperfect repeats in alpha-synuclein raises the question of whether or not mutations corresponding to E46K in the other imperfect KTKE(Q)GV repeats have similar effects on aggregation and fibrillation, as well as their propensities to form alpha-helices. To investigate the effect of E(Q)/K mutations in each imperfect repeat sequence, we substituted the amino acid corresponding to E46K in each of the seven repeated sequences with a Lys residue. The mutations in the imperfect KTKE(Q)GV repeat sequences of the N-terminal region were prone to decrease the lag time of fibril formation. In addition, AFM imaging suggested that the Q24K mutant formed twisted fibrils, while the other mutants formed spherical aggregates and short fibrils. These observations indicate that the effect of the mutations on the kinetics of fibril formation and morphology of fibrils varies according to their location.
authors: Department of Biotechnology, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Japan.
authors: Ryuichi
authors: R
authors: Harada
authors: Natsuki
authors: N
authors: Kobayashi
authors: Jihoon
authors: J
authors: Kim
authors: Chikashi
authors: C
authors: Nakamura
authors: Sung-Woong
authors: SW
authors: Han
authors: Kazunori
authors: K
authors: Ikebukuro
authors: Koji
authors: K
authors: Sode
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics*; D002942:Circular Dichroism; D006801:Humans; D008027:Light; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000648:ultrastructure; D020005:Propanols / Q000494:pharmacology; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D012542:Scattering, Radiation; D051844:alpha-Synuclein / Q000737:chemistry* / Q000648:ultrastructure; D006845:Hydrocarbons, Fluorinated
chemical_list: D050505:Mutant Proteins; D020005:Propanols; D051844:alpha-Synuclein; C497604:SNCA protein, human; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated