Tau is an intrinsically disordered protein found in the axons of neurons with roles in modulating microtubule dynamics and axonal transport. Tau dysfunction and aggregation is linked to various neurodegenerative disorders, including Alzheimer’s disease. Tau aggregates are marked by a variety of post translational modifications (PTMs). Acetylation and phosphorylation are of particular interest as they may be linked to cell signaling pathways. Here, we use genetic code expansion (GCE) to incorporate authentic acetyl-lysine as a non-canonical amino acid. We targeted pathologically relevant acetylation sites: K163, K174, K180, K274, K280, and K281. In addition to the authentic modifications, all sites were also investigated as glutamine acetylation mimics, and as K163/174/180Q and K274/280/281Q triple mimics. Light scattering was used to measure the impact of the modifications on microtubule polymerization kinetics and fluorescence correlation spectroscopy (FCS) was used to measure binding interactions. Acetylation imparted site-specific effects on microtubule polymerization kinetics, as well as tau-tubulin binding. Moreover, we validate the extent to which glutamine mimics, which could be used for multi-site and cell-based experiments, recapitulate the effects of bona-fide modification.
Saleh et al. (Sun,) studied this question.