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Analysis of β-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy
Published on: November 30, 2018
Off-pathway aggregation can inhibit fibrillation at high protein concentrations
Taru Deva1, Nikolai Lorenzen, Brian S Vad
1Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, University of Aarhus, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark. taru.deva@gmail.com
Biochimica Et Biophysica Acta
|January 15, 2013
Summary
Higher protein concentrations inhibit ribosomal protein S6 fibrillation by forming stable, off-pathway oligomers. This fibrillation inhibition occurs above a specific threshold concentration (CFR), influencing protein conformational states.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Misfolding Diseases
Background:
- Ribosomal protein S6 (S6) is prone to fibrillation under destabilizing conditions like elevated temperature and acidic pH.
- Protein fibrillation is implicated in various neurodegenerative diseases, making the study of fibrillation mechanisms crucial.
- Understanding factors that modulate protein fibrillation, such as protein concentration, is key to comprehending disease pathogenesis.
Purpose of the Study:
- To investigate the effect of protein concentration on the fibrillation of ribosomal protein S6.
- To elucidate the mechanism by which protein concentration influences S6 fibrillation.
- To characterize the nature of the species formed at high protein concentrations.
Main Methods:
- Spectroscopic techniques (e.g., circular dichroism) to monitor secondary structure.
- Size-exclusion chromatography to assess oligomeric states.
- Thioflavin T fluorescence assays to detect fibril formation.
- Pepsin digestion assays to evaluate proteinase resistance.
Main Results:
- S6 fibrillation is inhibited above a threshold concentration (CFR ≈ 3.5 mg/mL).
- High protein concentrations promote the formation of off-pathway oligomers with native-like secondary structure.
- These oligomers are in dynamic equilibrium with the monomer and can be overcome by fibril seeding.
- S6 forms distinct fibril types dependent on protein concentration.
- The off-pathway oligomers exhibit resistance to pepsin digestion.
Conclusions:
- Protein concentration acts as a critical regulator of S6 fibrillation, favoring off-pathway oligomerization above CFR.
- Fibrillation and off-pathway oligomerization are competing pathways for S6 under destabilizing conditions.
- The formation of distinct fibril morphologies highlights the conformational plasticity of S6.
- These findings offer insights into protein misfolding regulation and the potential for diverse conformational states in disease.
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