title: Self-oligomerization and protein aggregation of alpha-synuclein in the presence of Coomassie Brilliant Blue.
abstract: alpha-Synuclein has been implicated in various neurodegenerative disorders, including Parkinson's and Alzheimer's diseases, by its participation in abnormal protein depositions. As the protein has been suggested to play a significant role in the formation of the deposits which might be responsible for neurodegeneration, there is a strong demand to screen for alpha-synuclein-interactive small molecules. In this report, Coomassie Brilliant Blue (CBB) interaction of alpha-synuclein has been investigated with respect to induction of protein self-oligomerization in the presence of the chemical coupling reagent N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline. Both CBB-G and CBB-R, which differ by only two methyl groups, induced the self-oligomerization of alpha-synuclein in a biphasic manner with optimal dye concentrations of 250 microM and 150 microM, respectively. The protein aggregates of alpha-synuclein induced by the dyes in the absence of the coupling reagent were analysed by electron microscopy. Whereas CBB-G induced formation of protein aggregates with a worm-like structure, CBB-R induced clear fibrilization of alpha-synuclein on a background of granular structures. CBB-R interacted with alpha-synuclein approximately twice as effectively as CBB-G (dissociation constants 0.63 microM and 1.37 microM, respectively). These dye interactions were independent from the acidic C-terminus of alpha-synuclein, which was reminiscent of the Alphabeta25-35 interaction of alpha-synuclein. However, the metal-catalysed oxidative self-oligomerization of alpha-synuclein in the presence of Cu2+/H2O2, which was augmented synergistically by Alphabeta25-35, was not affected by the dyes. This indicates that the dye binding site is also distinctive from the Alphabeta25-35 interaction site on alpha-synuclein. These biochemically specific interactions between alpha-synuclein and the dyes indicate that alpha-synuclein-interactive small molecules could provide a tool with which to approach development of diagnostic, preventive, or therapeutic strategies for various alpha-synuclein-related neurodegenerative disorders.
authors.affiliation: Department of Biochemistry, College of Medicine, Inha University, 253 Yonghyun-Dong, Nam-Ku, Inchon 402-751, South Korea.
authors.forename: D
authors.initials: D
authors.lastname: Lee
authors.forename: E K
authors.initials: EK
authors.lastname: Lee
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: C S
authors.initials: CS
authors.lastname: Chang
authors.forename: S R
authors.initials: SR
authors.lastname: Paik
mesh_terms: D001665:Binding Sites; D006801:Humans; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D019636:Neurodegenerative Diseases / Q000209:etiology; D011487:Protein Conformation; D011804:Quinolines / Q000494:pharmacology; D012394:Rosaniline Dyes / Q000494:pharmacology*; D051843:Synucleins; D051844:alpha-Synuclein
chemical_list: D009419:Nerve Tissue Proteins; D011804:Quinolines; D012394:Rosaniline Dyes; C497604:SNCA protein, human; D051843:Synucleins; D051844:alpha-Synuclein; C000470:EEDQ; C024757:Coomassie brilliant blue R; C004692:coomassie Brilliant Blue