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Site-specific structural order in Alzheimer's Aβ42 fibrils
Hongsu Wang1, Yoon Kyung Lee1, Christine Xue1
1Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
Royal Society Open Science
|August 16, 2018
Summary
Alzheimer's disease amyloid fibrils are studied using spin labeling. This reveals specific structural ordering of amyloid-beta 42 (Aβ42) protein backbone, identifying key beta-strands, turns, and a partially ordered loop.
Area of Science:
- Biochemistry
- Structural Biology
- Neuroscience
Background:
- Amyloid fibril deposition is a key feature of Alzheimer's disease.
- Amyloid-beta 42 (Aβ42) aggregation forms these fibrils, making its structure crucial for understanding disease mechanisms and drug development.
Purpose of the Study:
- To investigate the site-specific structural order of Aβ42 fibrils at each residue.
- To provide insights into the backbone and side chain dynamics within Aβ42 fibrils.
Main Methods:
- Site-directed spin labeling (SDSL).
- Electron paramagnetic resonance (EPR) spectroscopy to analyze spin-spin interactions.
Main Results:
- Aβ42 fibrils exhibit a defined structure with five β-strands, three turns, and a loop.
- Strong spin-spin interactions at β-strand sites indicate high backbone order.
- Weak interactions at turn/loop sites suggest local disorder, with partial ordering observed in residues 24, 25, and 28 of the loop.
Conclusions:
- The study elucidates the detailed residue-level structural order in Aβ42 fibrils.
- Findings offer a complementary perspective to existing solid-state NMR and cryo-EM data.
- This detailed structural information aids in understanding Aβ42 aggregation and developing targeted therapies.