Characterization of The Non-fibrillar α-synuclein Oligomers
Document Type
Article
Publication Date
2011
Keywords
Amyloidosis, Fibrillation, Oligomer, Protein Aggregation, α-synuclein
Digital Object Identifier (DOI)
https://doi.org/10.2174/092986611794578332
Abstract
Under certain in vitro conditions, α-synuclein, an abundant 14kDa presynaptic intrinsically disordered protein involved in the pathogenesis of Parkinson's disease (PD), forms amyloid fibrils which resemble those found in Lewy bodies of PD patients. However, a substantial fraction of α-synuclein molecules (10-20%) does not form fibrils during fibrillation and exists in a form of soluble oligomers. In this study, we examined these soluble oligomers by a variety of biophysical techniques including atomic force microscopy (AFM), circular dichroism, Fourier-transform infrared spectroscopy and thioflavin T fluorescence. We observed that the fibrillation kinetics is affected by the variation in salt and protein concentrations. Although both high salt and high protein concentrations noticeably accelerated α-synuclein fibrillation, the amount of non-fibrillar oligomers is independent of the salt content. The oligomers formed at low salt concentration adopt more β-sheet structure and are smaller in size than those formed at high salt concentration. AFM analysis shows that the low salt oligomers represent a mixture of small oligomers and some amorphous aggregates, whereas oligomers formed at high salt concentrations are noticeably larger, more homogenous, and are mostly spherical in shape. All the late stage non-fibrillar oligomers do not form fibrils even when seeded with pre-formed fibrils, are characterized by negligible rates of dissociation, likely due to their intertwined structure, and are able to disrupt the integrity of the biological membrane. These findings suggest that these soluble oligomers are important players in the multi-pathway aggregation of α-synuclein and should be taken into account in studies on the molecular mechanisms of this protein fibrillation.
Was this content written or created while at USF?
Yes
Citation / Publisher Attribution
Protein and Peptide Letters, v. 18, issue 3, p. 230-240
Scholar Commons Citation
Hong, Dong-Pyo; Han, Shubo; Fink, Anthony L.; and Uversky, Vladimir N., "Characterization of The Non-fibrillar α-synuclein Oligomers" (2011). Molecular Medicine Faculty Publications. 477.
https://digitalcommons.usf.edu/mme_facpub/477
