Accumulation of intrinsically disordered protein tau in the form of insoluble aggregates is a common feature of neurodegenerative tauopathies. Tau protein is engaged in the regulation of microtubular dynamics in the neurons, however, under pathological conditions tau interacts with itself, escapes disordered state and forms toxic oligomers and aggregated filaments. Monoclonal antibody DC8E8 is able to inhibit tau-tau interaction [1, 2] and therefore it holds promise for the immunotherapy of Alzheimer’s disease. Minimal epitope of DC8E8 represents amino acid motif HXPGGG that is present in each of the four microtubule binding repeat regions (MTBRRs) of tau. Unravelling the unique mode of recognition of DC8E8 can aid to reveal hindered structural features of tau protein and their implication for tau protein biology.
In the presented study we have crystallized the Fab fragment of DC8E8 antibody with the peptides covering its epitopes from all four MTBRRs of tau, where the antibody Fab fragment serves as a crystallization chaperon for the disordered tau peptide. Using biophysical measurements, namely surface plasmon resonance and ELISA, we have found that the antibody has the highest affinity against the second MTBRR. The affinity for particular repeat regions descends as follows: MTBR2 > MTBR1 > MTBR3 > MTBR4.
This research has been supported by Axon Neuroscience SE APVV grant LPP-0038-09 and by VEGA grant number 2/0177/15