Expression and Purification of N-terminally Acetylated microtubule binding protein Tau

The microtubule-associated protein Tau (MAPT) plays a critical role in many neurodegenerative diseases. Tau functions to stabilize microtubule structures that are essential for transport within the neuron, and transport disruption leads to loss of neuronal function. Tau binding is regulated by phosphorylation with the help of kinases that add phosphate groups which block microtubule binding sites, and phosphatases that remove phosphate groups and expose the microtubule-binding regions. Tau can be found in hyper-phosphorylated states, which causes Tau to self-assemble into aggregates and prevent microtubule binding. It\u27s clear that post-translational modifications (PTMs) of Tau play a key role in the dysregulation of neuronal function due to abnormal conformational changes, however not all PTMs are as thoroughly studied as phosphorylation. N-terminal acetylation is the most common PTM of all proteins and Tau is predicted to be a target. N-terminal acetylation is a co-translational process that is catalyzed by N-terminal acetyltransferases, which adds an acetyl group to the N-terminus of Tau, thus neutralizing the positive charge on the N-terminus. Commonly, studies endogenously express Tau in a prokaryotic system that lack PTMs. Utilizing a co-expression system in E. coli allows for the purification of Tau with a modified N-terminus. Purifying modified Tau with Fast Protein Liquid Chromatography (FPLC) will allow us to probe the structural and functional effects of N-terminal acetylation by assessing changes in Tau’s aggregation and microtubule binding affinity and polymerization