Lysine acetylation regulates the activity of Escherichia coli S-adenosylmethionine synthase

Lysine acetylation is one of the most abundant post-translational modifications. However, physiological roles of this modification in bacteria are largely unknown. Previous protein acetylome analysis showed that Escherichia coli adenosylmethionine synthase (MAT) undergoes acetylation in vivo, but the biological functions of this modification still need to be uncovered. In this study, MAT of E. coli was over-expressed and purified. Subsequent mass spectrometry analysis showed that 12 lysine residues of the protein were acetylated. Site-directed mutagenesis analysis was performed and the results showed that acetylated lysine residues play important roles in the enzymatic activity of MAT. Next, deacetylation assay was performed by using CobB as the deacetylase, and the results showed that CobB could deacetylate MAT in vitro. In addition, the enzymatic activities of acetylated and deacetylated MAT were compared in vitro, and results showed that acetylation led to a decrease in its enzymatic activity, which could be reversed by CobB deacetylation. Altogether, our data suggest that CobB modulates the enzymatic activity of E. coli MAT in vitro.