Secondary structures transition of tau protein with intrinsically disordered proteins specific force field.

Microtubule-associated Tau protein plays a key role in assembling microtubule and modulating the functional organization of the neuron and developing axonal morphology, growth, and polarity. The pathological Tau can aggregate into cross-beta amyloid as one of the hallmarks for Alzheimer's disease (AD). Therefore, one of the top priorities in AD research is to figure out the structural model of Tau aggregation and to screen the inhibitors. The latest generation intrinsically disordered protein specific force field ff14IDPSFF significantly improved the distributions of heterogeneous conformations for intrinsically disordered proteins (IDPs). Here, the molecular dynamics (MD) simulations with three force fields of ff14SB, ff14IDPs, and ff14IDPSFF were employed to investigate the secondary structures transition of Tau (267-312) fragment. The results indicate that ff14IDPSFF can generate more heterogeneous conformers, and the predicted secondary structural distribution is closer to that of the experimental observation. In addition, predicted secondary chemical shifts from ff14IDPSFF are the most approach to those of experiment. Secondary structures transition kinetics for Tau(267-312) with ff14IDPSFF shows that the secondary structures were gradually transformed from α-helix to β-strand and the β-strand located at the regions of the residues 274-280 and residues 305-311. Besides, the driving force for the secondary structures transition of Tau(267-312) is mainly hydrophobic interactions which located at hexa-peptides VQIINK and VQIVYK . Secondary structure transition of Tau protein can give insight into the aggregation mechanism for AD.