Phosphorylation of the overlooked tyrosine 310 regulates the structure, aggregation, and microtubule- and lipid-binding properties of Tau

The microtubule-associated protein Tau is implicated in the pathogenesis of several neurodegenerative disorders, including Alzheimers disease. Increasing evidence suggests that post-translational modifications play critical roles in regulating Tau normal functions and its pathogenic properties in Tauopathies. Very little is known about how phosphorylation of tyrosine residues influences the structure, aggregation, and microtubule- and lipid-binding properties of Tau. In this work, we aimed to address this knowledge gap and determine the relative contribution of phosphorylation of one or several of the five tyrosine residues in Tau (Y18, Y29, Y197, Y310 and Y394) to the regulation of its biophysical, aggregation and functional properties. Towards this goal, we used a combination of site-specific mutagenesis and in vitro phosphorylation by c-Abl kinase to generate Tau species phosphorylated at all tyrosine residues, all tyrosine residues except Y310 or Y394 (pTau-Y310F, pTau-Y394F) and Tau phosphorylated only at Y310 or Y394 (4F\pY310 or 4F\pY394). Our results show that phosphorylation at all five tyrosine residues, multiple N-terminal tyrosine residues (Y18, Y29 and Y197) or site-specific phosphorylation at residue Y310, itself located in the microtubule-binding and aggregation-prone domain of Tau, was sufficient to abolish Tau aggregation and inhibit its microtubule- and lipid-binding properties. NMR studies demonstrated that these effects were mediated by a local decrease in {beta}-sheet propensity of the PHF6 domain. Our findings underscore the unique role of Y310 phosphorylation in the regulation of Tau aggregation, microtubule and lipid interactions and highlight the importance of conducting further studies to elucidate its role in the regulation of Tau normal functions and its pathogenic properties.