Interaction of the Tau fibrils with the neuronal membrane†

Tau proteins are gaining a lot of interest recently due to their active role in causing a range of tauopathies. Molecular mechanisms underlying the tau interaction with the neuronal membrane are hitherto unknown and difficult to characterize using conventional experimental methods. Starting from the cryo-EM structure of the tau fibrils, we have used atomistic molecular dynamics simulations to model the interaction between the fibril and neuronal membrane, with explicit solvation. The dynamics and structural characteristics of the tau fibril with the neuronal membrane are compared to the tau fibril in the aqueous phase to corroborate the effect of the neuronal membrane on the tau structure. The tau fibrils are in general more compact in the presence of neuronal membrane compared to their structure in the water medium. We find that the number of β -sheet residues of the tau fibrils are different in the case of two polymorphs, paired helical filament and straight filaments (PHF and SF) in the two media. PHF is found to approach closer to the neuronal membrane than the SF. The negatively charged lipids in the neuronal membrane are found to mediate the tau-neuronal membrane binding. Our study initiates the understanding of tau conformational ensemble in the presence of neuronal membrane and sheds light on the significant tau – membrane interactions. The simulation times of our report might limit the conformational sampling required to observe membrane permeation, nevertheless it provides significant insights into fibril – neuronal membrane interactions.