Sirtuin-dependent reversible lysine acetylation of the <i>o</i> -succinylbenzoyl-coenzyme A synthetase of <i>Bacillus subtilis</i>

Reversible lysine acylation (RLA) is a conserved posttranslational modification that cells of all domains of life use to regulate the biological function of proteins, some of which have enzymatic activity. Many AMP-forming organic acid:CoA ligases are regulated <i>via</i> acylation in prokaryotes and eukaryotes. Here, we report the acetylation of the <i>o</i>-succinylbenzoyl-CoA synthetase (EC 6.2.1.26) of <i>Bacillus subtilis</i> (<i>Bs</i>MenE) by the GCN5-related acetyltransferase (GNAT) AcuA enzyme of this bacterium. <i>Bs</i>MenE is part of the metabolic pathway that assembles menaquinone (MK), an essential component of the electron transport chain in <i>B. subtilis</i>. We demonstrate that the active-site lysine 471 (K471) of <i>Bs</i>MenE is acetylated specifically by <i>Bs</i>AcuA, and that acetylated <i>Bs</i>MenE (<i>Bs</i>MenE^Ac) is deacetylated by the NAD⁺-dependent sirtuin (<i>Bs</i>SrtN) of this bacterium. The <i>in vivo</i> analyses performed in this study were done in an <i>Escherichia coli</i> Δ<i>menE</i> strain because the enzymatic activity of MenE is essential in <i>B. subtilis</i>, but not in <i>E. coli</i>. The use of a heterologous system allowed us to assess the effect of acetylation on <i>Bs</i>MenE function under MK-dependent growth conditions. Based on our <i>in vivo</i> data, we suggest that regulation of <i>Bs</i>MenE by RLA reduces MK production, negatively affecting the growth rate and yield of the culture.IMPORTANCEReversible lysine acylation (RLA) is a posttranslational modification used by all cells to rapidly control the biological function of proteins. Herein, we identify an acetyltransferase and deacetylase in the soil bacterium <i>Bacillus subtilis</i> that can modify/demodify an enzyme required for the synthesis of menaquinone (MK), an essential electron carrier involved in respiration in cells of all domains of life. Based on our data, we suggest that under some as-yet-undefined physiological conditions, <i>B. subtilis</i> modulates MK biosynthesis, which changes the flux of electrons through the electron transport chain of this bacterium. To our knowledge, this is the first example of control of respiration by RLA.