title: Distinct Mechanisms Determine α-Synuclein Fibril Morphology during Growth and Maturation.
abstract: Amyloid polymorphs have become one of the focal points of molecular studies of neurodegenerative diseases like Parkinson's disease. Due to their distinct biochemical properties and prion-like characteristics, insights into the molecular origin and stability of amyloid polymorphs over time are crucial for understanding the potential role of amyloid polymorphism in these diseases. Here, we systematically study the fibrillization of recombinantly produced human α-synuclein (αSyn) over an extended period of time to unravel the origin and temporal evolution of polymorphism. We follow morphological changes in the same fibril sample with atomic force microscopy over a period of 1 year. We show that wild-type (wt) αSyn fibrils undergo a slow maturation over time after reaching the plateau phase of aggregation (as detected in a Thioflavin-T fluorescence assay). This maturation, visualized by changes in the fibril periodicity over time, is absent in the disease mutant fibrils. The β-sheet content of the plateau phase and matured fibrils, obtained using Fourier transform infrared spectroscopy, is however similar for the αSyn protein sequences, suggesting that the morphological changes in wt αSyn fibrils are tertiary or quaternary in origin. Furthermore, results from a reversibility assay show that the plateau phase fibrils do not disassemble over time. Together, the observed changes in the periodicity distributions and stability of the fibrillar core over time point toward two distinct mechanisms that determine the morphology of wt αSyn fibrils: competitive growth between different polymorphs during the fibrillization phase followed by a process wherein fibrils undergo slow maturation or annealing.
authors.affiliation: Nanobiophysics, MESA+ Institute for Nanotechnology, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.
authors.forename: Arshdeep
authors.identifier: 0000-0002-2851-1019
authors.initials: A
authors.lastname: Sidhu
authors.affiliation: Nanobiophysics, MESA+ Institute for Nanotechnology, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.
authors.forename: Ine
authors.initials: I
authors.lastname: Segers-Nolten
authors.affiliation: Structural Biology and Bioinformatics Centre, Structure and Function of Biological Membranes, Faculty of Science, Université Libre de Bruxelles , B-1050 Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Raussens
authors.affiliation: Nanobiophysics, MESA+ Institute for Nanotechnology, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.|MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.
authors.forename: Mireille M A E
authors.initials: MM
authors.lastname: Claessens
authors.affiliation: Nanobiophysics, MESA+ Institute for Nanotechnology, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.|MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente , Postbox 217, 7500 AE Enschede, The Netherlands.|Vrije Universiteit Amsterdam , De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands.
authors.forename: Vinod
authors.initials: V
authors.lastname: Subramaniam
mesh_terms: D052160:Benzothiazoles; D002942:Circular Dichroism; D006801:Humans; D018625:Microscopy, Atomic Force; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D066263:Protein Aggregation, Pathological / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013844:Thiazoles / Q000378:metabolism; D013997:Time Factors; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D052160:Benzothiazoles; D046912:Multiprotein Complexes; D013844:Thiazoles; D051844:alpha-Synuclein; C009462:thioflavin T
keywords: amyloid; atomic force microscopy; growth mechanisms; polymorphism; α-Synuclein