The Effects of N‐terminal Acetylation on the Protein Tau

Abstract

The microtubule‐associated protein tau (MAPT) plays a critical role in many neurodegenerative diseases such as Alzheimer’s Disease. Tau functions to stabilize microtubule structures that are essential for transport within the neuron, and disruption of transport leads to a loss of neuronal function. Tau binding is regulated by phosphorylation, a post‐translational modification (PTM) where a phosphate group is added by a specific kinase. Phosphorylated Tau blocks the microtubule binding sites, then phosphatases remove these phosphate groups which expose the microtubule‐binding regions. Tau is also found in a hyper‐phosphorylated state, which causes Tau to self‐assemble into oligomers and higher order aggregates. It's clear that post‐translational modification of Tau plays a key role in the dysregulation of neuronal function due to abnormal conformational changes, however not all PTMs are as thoroughly studied as phosphorylation.However, N‐terminal acetylation is the most common and overlooked PTM of all protein, this is adjacent to the proven idea of Tau being a predicted target of N‐terminal acetylation. N‐terminal acetylation is a co‐translational process that is catalyzed by N‐terminal Acetyltransferases (NATs), which adds an acetyl group to the N‐terminus of a Tau polypeptide, thus neutralizing the positive charge on the N‐terminus.The objective of this research is to understand how the N‐terminal modification of a Tau polypeptide effects the behavior of Tau and its aggregation. Commonly, studies endogenously express Tau in a prokaryotic system that lack PTMs. Here we utilize a co‐expression system in E. coli that allows us to purify 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. Furthermore, our studies of the N‐terminus of Tau will provide insight into the role of the N‐terminal projection domain and potentially provide new targets for therapeutic intervention in the treatment of Tau related diseases.Support or Funding InformationCollaborative Award through RI‐INBRE from the National Institute of General Medical Sciences of the National Institute of Health under grant #P20GM103430.