Comprehensive search for novel lysine acyl modifications derived from L-theanine

Abstract

Recently, it has been suggested that there are more than 3,000 proteins are acetylated in human cells, which are thought to regulate diverse biological processes. Recently, it has been shown that beside acetylation, lysine residues undergo various types of acylations. Some of these lysine acylations occur depending on acyl-CoA derived from endogenous carboxylic acids such as fatty acids. We are exposed daily to a variety of compounds with food, including carboxylic acids. These living environment-derived carboxylic acids may modify lysine residues of proteins in vivo through chemical reactions. Indeed, we found that L-theanine, a well-known amino acid unique to green tea, has the potential to modify to proteins in cells. This study aimed to explore novel lysine acyl modifications induced by L-theanine using click chemistry, a selective reaction between alkyne and azide. Cells were treated with alkyne-labeled L-theanine, and L-theanine alkynes incorporated into proteins as acylation were detected by click chemistry with fluorescent azide. These analyses suggest that many proteins are modified by L-theanine. Furthermore, chase experiments revealed that L-theanine modification is reversible. Currently, we are conducting to comprehensively search for proteins modified by L-theanine using click chemistry with biotin azide, and would like to introduce this attempt in this presentation.