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Single-molecule visualization determines conformational substate ensembles in β-sheet-rich peptide fibrils
Wenbo Zhang1, Ruonan Wang1, Mingwei Liu1
1State Key Laboratory of Medical Molecular Biology, Haihe Laboratory of Cell Ecosystem, Department of Biophysics and Structural Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, P. R. China.
Scanning tunneling microscopy (STM) reveals over 10 protein conformational substates in peptides like keratin and amyloid. This single-molecule imaging technique captures detailed conformational ensembles, aiding in understanding peptide interactions.
Area of Science:
- Biophysics
- Structural Biology
- Materials Science
Background:
- Understanding protein conformational ensembles is crucial for elucidating interpeptide recognition and association mechanisms.
- Experimentally resolving multiple coexisting conformational substates presents a significant challenge in molecular studies.
Purpose of the Study:
- To develop and apply scanning tunneling microscopy (STM) for analyzing conformational substate ensembles of beta-sheet peptides at submolecular resolution.
- To investigate the conformational dynamics of keratin and amyloid peptides and their mutants.
Main Methods:
- Utilized scanning tunneling microscopy (STM) for single-molecule imaging of peptide assemblies.
- Achieved submolecular resolution (in-plane <2.6 Å) to resolve conformational substates.
- Analyzed conformational ensembles of keratin (KRT), Aβ42, and TDP-43 peptides and their mutants.
Main Results:
- Observed ensembles of over 10 conformational substates with free energy fluctuations in the range of several kBT.
- Detected changes in conformational ensembles of peptide mutants, correlating with macroscopic assembly properties.
- Demonstrated STM's capability to capture detailed conformational substate pictures and energetic landscapes.
Conclusions:
- STM-based single-molecule imaging provides a powerful method for characterizing complex protein conformational ensembles.
- This technique can rapidly screen conformational landscapes and complement traditional characterization methods.
- The findings offer insights into the energetic landscape of interconformational interactions in peptide assemblies.
