Dresser, Lara, Hunter, Patrick, Yendybayeva, Fatima et al. (5 more authors) (2021) Amyloid-β oligomerization monitored by single-molecule stepwise photobleaching. Methods. pp. 80-95. ISSN 1046-2023
Abstract
A major hallmark of Alzheimer’s disease is the misfolding and aggregation of the amyloid- β peptide (Aβ). While early research pointed towards large fibrillar- and plaque-like aggregates as being the most toxic species, recent evidence now implicates small soluble Aβ oligomers as being orders of magnitude more harmful. Techniques capable of characterizing oligomer stoichiometry and assembly are thus critical for a deeper understanding of the earliest stages of neurodegeneration and for rationally testing next-generation oligomer inhibitors. While the fluorescence response of extrinsic fluorescent probes such as Thioflavin-T have become workhorse tools for characterizing large Aβ aggregates in solution, it is widely accepted that these methods suffer from many important drawbacks, including an insensitivity to oligomeric species. Here, we integrate several biophysics techniques to gain new insight into oligomer formation at the single-molecule level. We showcase single-molecule stepwise photobleaching of fluorescent dye molecules as a powerful method to bypass many of the traditional limitations, and provide a step-by-step guide to implementing the technique in vitro. By collecting fluorescence emission from single Aβ(1–42) peptides labelled at the N-terminal position with HiLyte Fluor 555 via wide-field total internal reflection fluorescence (TIRF) imaging, we demonstrate how to characterize the number of peptides per single immobile oligomer and reveal heterogeneity within sample populations. Importantly, fluorescence emerging from Aβ oligomers cannot be easily investigated using diffraction-limited optical microscopy tools. To assay oligomer activity, we also demonstrate the implementation of another biophysical method involving the ratiometric imaging of Fura-2-AM loaded cells which quantifies the rate of oligomer-induced dysregulation of intracellular Ca2+ homeostasis. We anticipate that the integrated single-molecule biophysics approaches highlighted here will develop further and in principle may be extended to the investigation of other protein aggregation systems under controlled experimental conditions.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 The Authors. |
Keywords: | Amyloid oligomerization,Calcium sensing,Fluorescence,Photobleaching,Single-molecule TIRF |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) The University of York > Faculty of Sciences (York) > Biology (York) The University of York > Faculty of Sciences (York) > Chemistry (York) The University of York > Faculty of Sciences (York) > Centre for Immunology and Infection (CII) (York) |
Depositing User: | Pure (York) |
Date Deposited: | 15 Jun 2020 15:40 |
Last Modified: | 16 Oct 2024 16:40 |
Published Version: | https://doi.org/10.1016/j.ymeth.2020.06.007 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1016/j.ymeth.2020.06.007 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:161816 |
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