Microtubule associated protein tau is the main actor of tau hypothesis of Alzheimer´s disease (AD). Tau belongs to intrinsically disordered proteins (IDPs) which do not acquire any stable secondary nor tertiary structure. Under pathological conditions of tauopathy, tau dissociates from microtubules to form insoluble filaments with disease specific fold. It was previously shown that the presence of two hexapeptide sequences (VQIxxK) can trigger the protein aggregation [1]. Recently it was shown that the AD specific fold of tau filament can be recapitulated in vitro by aggregation of truncated tau 297-391 (dGAE) [2].
It was long believed that aggregation prone sequences were responsible for tau aggregation. It begins to be apparent that sequences in R’ region that follow tau MTBR repeats play a crucial role in MT binding and potentially also in aggregation process [3]. Tau oligomers that spread the specific disease fold strain may be the pathological agent of disease and their structural features remain still elusive.
Recombinant truncated tau proteins tau306-391, tau316-391, tau321-391 and tau326-391 were aggregated under different conditions (presence of heparin and DTT). Results of aggregation were monitored using different techniques: ThT fluorescence, DLS, AFM, FTIR and capillary electrophoresis.
We have observed in vitro aggregation of several tau proteins, mainly tau 321-391 which lacks the aggregation prone sequence VQIVYK (PHF6 epitope). Early signs of oligomer formation were observed by measurements using capillary electrophoresis. The results will further widen the knowledge about pathological aggregation of tau proteins.
This work was supported by APVV-21-0479 grant.