title: Wildtype and A30P mutant alpha-synuclein form different fibril structures.
abstract: Parkinson's Disease (PD) is a neurodegenerative movement disorder affecting millions of people worldwide. One of the key players in the development of the disease is the protein α-synuclein (aSN), which aggregates in the brain of PD patients. The aSN mutant A30P has been reported to cause early-onset familial PD and shows different aggregation behavior compared to wt aSN. Here we use a multidisciplinary approach to compare the aggregation process of wt and A30P aSN. In agreement with previous studies, we observe an initial lag phase followed by a continuous structural development of fibrils until reaching an apparent monomer-aggregate equilibrium state and a plateau in Thioflavin T (ThT) fluorescence intensity. However, at later timepoints A30P shows greater propensity than αSN wt to form dense bundled fibril networks. Combining small angle x-ray scattering, x-ray fibre diffraction and linear dichroism, we demonstrate that while the microscopic structure of the individual fibril essentially remains constant throughout the experiment, the formation of dense A30P fibril networks occur through a continuous assembly pathway while the formation of less dense wt fibril networks with fewer contact points follows a continuous path during the elongation phase and a second rearrangement phase after reaching the ThT fluorescence plateau. Our work thus highlights that structural rearrangements proceed beyond the plateau in ThT-based monitoring of the fibrillation process, and the density and morphology of the resulting fibril networks is highly dependent on the aSN form studied.
authors.affiliation: Center for Insoluble Protein Structures (inSPIN), and Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
authors.forename: Søren Bang
authors.initials: SB
authors.lastname: Nielsen
authors.forename: Francesca
authors.initials: F
authors.lastname: Macchi
authors.forename: Samuele
authors.initials: S
authors.lastname: Raccosta
authors.forename: Annette Eva
authors.initials: AE
authors.lastname: Langkilde
authors.forename: Lise
authors.initials: L
authors.lastname: Giehm
authors.forename: Anders
authors.initials: A
authors.lastname: Kyrsting
authors.forename: Anna Sigrid Pii
authors.initials: AS
authors.lastname: Svane
authors.forename: Mauro
authors.initials: M
authors.lastname: Manno
authors.forename: Gunna
authors.initials: G
authors.lastname: Christiansen
authors.forename: Niels Christian
authors.initials: NC
authors.lastname: Nielsen
authors.forename: Lene
authors.initials: L
authors.lastname: Oddershede
authors.forename: Bente
authors.initials: B
authors.lastname: Vestergaard
authors.forename: Daniel Erik
authors.initials: DE
authors.lastname: Otzen
mesh_terms: D052160:Benzothiazoles; D004926:Escherichia coli / Q000235:genetics; D005456:Fluorescent Dyes; D006801:Humans; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D053838:Scattering, Small Angle; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013844:Thiazoles; D014961:X-Ray Diffraction; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D052160:Benzothiazoles; D005456:Fluorescent Dyes; D011994:Recombinant Proteins; D012996:Solutions; D013844:Thiazoles; D051844:alpha-Synuclein; C009462:thioflavin T