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The Properties of α-Synuclein Secondary Nuclei are Dominated by the Solution Conditions Rather than the Seed Fibril Strain

preprint
submitted on 01.09.2019 and posted on 04.09.2019 by Alessia Peduzzo, Sara Linse, Alexander Buell
α-synuclein (α-syn) is a natively unfolded protein predominantly localized in the presynaptic terminals of neurons. It has been shown that α-syn fibrils are the major component of abnormal neuronal aggregates known as Lewy bodies, the characteristic hallmark of Parkinson’s disease. Amyloid fibrils arise through primary nucleation from monomers, which in the case of α-syn is accelerated by suitable surfaces with an affinity for the protein, followed by the elongation of the nuclei by monomer addition. Secondary nucleation, on the other hand, corresponds to the formation of new fibrils when it is facilitated by pre-existing fibrils. While
α-synuclein (α-syn) is a natively unfolded protein predominantly localized in the presynaptic terminals of neurons. It has been shown that α-syn fibrils are the major component of abnormal neuronal aggregates known as Lewy bodies, the characteristic hallmark of Parkinson’s disease. Amyloid fibrils arise through primary nucleation from monomers, which in the case of α-syn is accelerated by suitable surfaces with an affinity for the protein, followed by the elongation of the nuclei by monomer addition. Secondary nucleation, on the other hand, corresponds to the formation of new fibrils when it is facilitated by pre-existing fibrils. While it is well-established that the newly added monomer in the process of fibril elongation adopts the conformation of the monomers in the seed, often called templating, it is still unclear under which conditions fibrils formed through secondary nucleation of monomers on the surface of fibrils copy the structure of the parent. Here we show by biochemical and microscopical methods that the secondary nucleation of α-syn, enabled at mildly acidic pH, leads to fibrils that structurally resemble more closely those formed de novo under the same conditions, rather than the seeds if these are formed under different solution condition. This result has important implications for the mechanistic understanding of the secondary nucleation of amyloid fibrils and its role in the propagation of aggregate pathology in protein misfolding diseases.

Funding

Parkinson's and Movement Disorder Foundation

Novo Nordisk Foundation

JPND

Swedish Research Council

History

Email Address of Submitting Author

alebu@dtu.dk

Institution

Technical University of Denmark

Country

Denmark

ORCID For Submitting Author

0000-0003-1161-3622

Declaration of Conflict of Interest

no conflict of interest

Exports