Molecular Dynamics Study of the Interaction between the N-terminal of α-Synuclein and a Lipid Bilayer Mimicking Synaptic Vesicles.

The interaction between α-synuclein (α-syn) and synaptic vesicles (SVs) plays an important role in the life cycle of α-syn, and a disruption of it could lead to numerous neurodegenerative diseases. The N-terminal of α-syn (first 15 residues) has been shown to recapitulate the association dynamics of α-syn to the bilayer in various studies. This manuscript presents an extensive all-atom molecular dynamics studies (close to 100 μs) of the interaction between the N-terminal of α-syn and a lipid bilayer that mimics the SV under physiological conditions. The research demonstrates α-syn's overwhelming binding preference to the outer leaflet of the SV, which carries a net negative charge as compared to the neutral inner leaflet. Further structural analysis reveals that the Coulombic interaction between the positively charged residues of α-syn and the negatively charged lipid surface is the driving force of the binding, but has a potential of hindering the configurational change of α-syn. In addition, metadynamics simulations are carried out to investigate the folding of the N-terminal of α-syn in the presence and absence of the lipid bilayer, and the result confirms that the α-syn/membrane association facilitates protein folding.