Intracellular acetyl phosphate modulates Escherichia coli pyruvate metabolism

Lysine acetylation has been shown to be an abundant and vital post-translational modification (PTM) that utilizes acetyl phosphate (AcP) as one of the acetyl group donors in bacteria. The pyruvate dehydrogenase (PDH) complex catalyzes the conversion from pyruvate to acetyl coenzyme A (acetyl-CoA). Thus far, the connection between lysine acetylation and pyruvate metabolism has not been thoroughly investigated. In this study, we show that AcP could acetylate Escherichia coli pyruvate dehydrogenase (AceE) in vitro and in vivo, which could be reversed by protein lysine deacetylase (CobB). In vitro treatment of AceE with AcP also causes increased phosphorylation of the protein, whereas deleting ackA does not affect the phosphorylation of the protein. As a result, in vitro treatment of AceE by AcP leads to decreased enzymatic activity. In contrast, deleting ackA leads to increased acetylation and enzymatic activity of AceE, and deleting pta results in the decreased acetylation and enzymatic activity of AceE. As expected, deleting pta in E. coli causes pyruvate accumulation. Although deleting ackA also causes pyruvate accumulation, decreased expression of the two genes involved in pyruvate metabolism ( ldhA and poxB) is observed in the mutant, indicating that AcP could affect pyruvate metabolism by other routes in addition to modulating the AceE activity. Thus, our results demonstrate that intracellular AcP could modulate pyruvate metabolism in E. coli. For the first time, a linkage between AcP-mediated protein lysine acetylation, pyruvate dehydrogenase activity, and pyruvate metabolism is established.