Proteome Wide Profiling of -ε-Lysine Acetylation Reveals a Novel Mechanism of Regulation of the Chitinase Activity in .

is a Gram-negative bacterium that causes the zoonotic disease tularemia. The historical development of tularemia as a biological weapon has led to it being characterized by the CDC as a category A biothreat agent. Neither posttranslational modification (PTM) of proteins, in particular lysine acetylation, in nor its subsequent regulation of the protein activity has been well studied. In this work, we analyze -ε-lysine acetylation of the ssp. proteome by mass spectrometry for the first time. To create a comprehensive acetylation profile, we enriched protein acetylation using two approaches: (1) the addition of glucose or acetate into the culture medium and (2) direct chemical acetylation of -ε-lysines with acetyl phosphate. We discovered 280 acetylated proteins with 1178 acetylation sites in the ssp. strain U112. Lysine acetylation is an important PTM that regulates multiple cellular processes in bacteria, including metabolism, transcription, translation, stress response, and protein folding. We discovered that chitinases A and B are acetylated naturally and when chemically induced by acetyl phosphate. Moreover, chemical overacetylation of chitinases results in silencing of the enzymatic activity. Our findings suggest a novel mechanism of posttranslational regulation of the chitinase activity and that acetylation may play a role in 's regulation of the protein activity.