Computational Investigation on Tyrosine to Alanine Mutations Delaying the Early Stage of α-Synuclein Aggregation

Abstract

Background: Aggregation of Human α-synuclein protein into well-ordered amyloid fibrils is critical at the onset of Parkinson’s disease (PD), a progressive and irreversible neurodegenerative disorder. In the recent past, the importance of tyrosine residues in the fibrillation process of α-synuclein has been highlighted but their definite role in the early events of fibrillation is not clear. Objective: To understand the role of Tyr residues on the early events of α-synuclein fibrillation process. Methodology: We have used the all the atom molecular dynamics simulation and investigated the conformational dynamics of wild-type (WT) and the three modelled Tyr mutants (Y39A, Y133A, and Y (125,133,136) A) of α-synuclein. Results: Among the WT and the mutants, we observed Y(125, 133, 136)A and Y133A to have lesser number of hydrophobic contacts between the residues in the N- and C-terminal regions, exhibiting a differing folding pattern and conformation that has the ability to delay the aggregation propensity of α-synuclein. We also found that Tyr residue at position 133 is primarily important to drive the intramolecular interactions and subsequent fibrillation process. Conclusion: Therefore, our findings in this study suggest that targeting the Tyr residue at the position 133 may provide better solution to significant delay in the early stage of aggregation in α- synuclein. Keywords: Amyloid, fibrillation, molecular dynamics, parkinson’s disease, protein folding.