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Aqueous, Unfolded OmpA Forms Amyloid-Like Fibrils upon Self-Association
Emily J Danoff1, Karen G Fleming1
1T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States of America.
Plos One
|July 22, 2015
Summary
Outer membrane protein A (OmpA) self-associates into amyloid-like fibrils. This discovery offers a new model for studying protein fibrillization and suggests chaperone proteins may prevent this process.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- Unfolded outer membrane beta-barrel proteins can self-associate without lipid bilayers.
- Previous work showed OmpA forms high molecular weight species with non-native β-sheet structure.
Purpose of the Study:
- To investigate the conformation of self-associated OmpA.
- To determine if OmpA forms amyloid-like structures.
Main Methods:
- Monitoring Thioflavin T dye binding.
- Electron microscopy of self-associated OmpA species.
- Analysis of previous kinetic data on OmpA self-association.
Main Results:
- Thioflavin T binding increased significantly, indicating cross-β structure.
- Electron microscopy revealed fibrillar species.
- Results align with a nucleated growth polymerization mechanism.
Conclusions:
- OmpA self-association leads to the formation of amyloid-like fibrils.
- OmpA serves as a novel model for studying protein fibrillization.
- Periplasmic chaperone proteins may inhibit OmpA fibril formation.
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