Molecular-level insights of early-stage prion protein aggregation on mica and gold surface determined by AFM imaging and molecular simulation.
By in situ time-lapse AFM, we investigated early-stage aggregates of PrP formed at low concentration (100 ng/mL) on mica and Au(111) surfaces in acetate buffer (pH 4.5). Remarkably different PrP assemblies were observed. Oligomeric structures of PrP aggregates were observed on mica surface, which was in sharp contrast to the multi-layer PrP aggregates yielding parallel linear patterns observed Au(111) surface. Combining molecular dynamics and docking simulations, PrP monomers, dimers and trimers were revealed as the basic units of the observed aggregates. Besides, the mechanisms of the observed PrP aggregations and the corresponding molecular-substrate and intermolecular interactions were suggested. These interactions involved gold-sulfur interaction, electrostatic interaction, hydrophobic interaction, and hydrogen binding interaction. In contrast, the PrP aggregates observed in pH 7.2 PBS buffer demonstrated similar large ball-like structures on both mica and Au(111) surfaces. The results indicate that the pH of a solution and the surface of the system can have strong effects on supramolecular assemblies of prion proteins. This study provides in-depth understanding on the structural and mechanistic nature of PrP aggregation, and can be used to study the aggregation mechanisms of other proteins with similar misfolding properties.
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30605, USA; College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China.
Zhichao
Z
Lou
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30605, USA.
Bin
B
Wang
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30605, USA.
Cunlan
C
Guo
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30605, USA.
Kun
K
Wang
College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China.
Haiqian
H
Zhang
Single Molecule Study Laboratory, College of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, GA 30605, USA. Electronic address: bxu@engr.uga.edu.
Bingqian
B
Xu
D000085:Acetates / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry*; D003198:Computer Simulation; D006046:Gold / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D062105:Molecular Docking Simulation; D011328:Prions / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D055672:Static Electricity; D013455:Sulfur / Q000737:chemistry; D013499:Surface Properties
D000085:Acetates; D000538:Aluminum Silicates; D011328:Prions; D013455:Sulfur; D006046:Gold; C011934:mica
Atomic force microscopy; Computational simulations; Early-stage aggregation; Interfaces; Prion protein