KARS mediates intra-translational deposition ofN⁶-acetyl-L-lysine in nascent proteins to contribute the acetylome in cells

Abstract

N6-acetyl-L-lysine residue is abundant in dietary protein but less is known about its potential influences on the diet-consumers. We herein report that N6-acetyl-L-lysine residues in acetylated dietary protein directly contributes to the acetylome in animal. By feeding mice with deuterium-labelled N6-acetyl-L-lysine-proteins, we demonstrated that acetylated dietary protein is a direct source of N6-acetyl-L-lysine that can widely contribute the acetylome in organs of liver, brain, and lung in mice. In mammalian cells, N6-acetyl-L-lysine can be utilized by Lysyl-tRNA synthetase (KARS) to generate N6-acetyl-L-lysyl-tRNA, which introduces N6-acetyl-L-lysine into the growing nascent polypeptide and intra-translationally results in protein acetylation. Co-crystal structure of KARS in complex with N6-acetyl-L-lysyl-AMP and pyrophosphate, coupled with in vitro biochemical assays, further confirms a sequential mechanism that KARS produces N6-acetyl-L-lysyl-AMP and transfers the N6-acetyl-L-lysyl-moiety to lysine cognate tRNA to generate N6-acetyl-L-lysyl-tRNA. Together, the present study establishes a model that N6-acetyl-L-lysine bridges the influence of acetylated dietary protein to the acetylome in dietary protein-consumer. Importantly, an undocumented mechanism that intra-translationally deposit acetylation in nascent proteins has been proved. It might extend the repertoire of acetylome and improves our understandings in protein modification modes in cells.