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Jang C, Portugal Barron D, Duo L, Ma C, Seabaugh H, Guo Z. EPR Studies of Aβ42 Oligomers Indicate a Parallel In-Register β-Sheet Structure. ACS Chem Neurosci 2024; 15:86-97. [PMID: 38109787 PMCID: PMC10767747 DOI: 10.1021/acschemneuro.3c00364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 10/31/2023] [Accepted: 11/30/2023] [Indexed: 12/20/2023] Open
Abstract
Aβ aggregation leads to the formation of both insoluble amyloid fibrils and soluble oligomers. Understanding the structures of Aβ oligomers is important for delineating the mechanism of Aβ aggregation and developing effective therapeutics. Here, we use site-directed spin labeling and electron paramagnetic resonance (EPR) spectroscopy to study Aβ42 oligomers prepared by using the protocol of Aβ-derived diffusible ligands. We obtained the EPR spectra of 37 Aβ42 oligomer samples, each spin-labeled at a unique residue position of the Aβ42 sequence. Analysis of the disordered EPR components shows that the N-terminal region has a lower local structural stability. Spin label mobility analysis reveals three structured segments at residues 9-11, 15-22, and 30-40. Intermolecular spin-spin interactions indicate a parallel in-register β-sheet structure, with residues 34-38 forming the structural core. Residues 16-21 also adopt the parallel in-register β-structure, albeit with weaker intermolecular packing. Our results suggest that there is a structural class of Aβ oligomers that adopt fibril-like conformations.
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Affiliation(s)
- Chelsea Jang
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Diana Portugal Barron
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Lan Duo
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Christine Ma
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Hanna Seabaugh
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Zhefeng Guo
- Department of Neurology,
Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, United States
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