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β-Sheet Assembly Translates Conservative Single-Site Mutation into a Perturbation in Macroscopic Structure
Wenbo Zhang1, Mingwei Liu1, Yang Wang1
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.
Single amino acid changes in synthetic peptides significantly alter their macroscale assembly and properties. This study reveals how small sequence variations amplify to affect protein quaternary structure and fibril formation.
Area of Science:
- Biochemistry
- Materials Science
- Structural Biology
Background:
- Designing protein quaternary structure by transferring sequence information to macroscale assembly is challenging.
- The mechanism by which minor sequence variations cause global structural perturbations remains unclear.
Purpose of the Study:
- To investigate how a single amino acid substitution affects peptide self-assembly and macroscopic properties.
- To elucidate the relationship between single-molecule structure and large-scale assembly behavior.
Main Methods:
- Design and synthesis of two peptides, QNL-His and QNL-Arg, differing by one amino acid.
- Imaging of individual peptides using scanning tunneling microscopy (STM) to determine folding and supramolecular organization.
- Analysis of β-sheet structure, fibril formation, and phase transitions.
Main Results:
- STM revealed distinct β-strand length distributions and pleated β-sheet associations for QNL-His and QNL-Arg.
- Structural differences at the single-molecule level led to distinguishable outcomes in assembled fibrils and phase transitions.
- The study demonstrated amplification of single-site mutation effects from molecular to macroscopic scales.
Conclusions:
- Assembly processes amplify subtle, single-site sequence variations into significant differences in macroscopic properties.
- Understanding this amplification is crucial for designing protein quaternary structures and predicting assembly outcomes.
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