A single regulator NrtR controls bacterial NAD homeostasis via its acetylation.

Nicotinamide adenine dinucleotide (NAD) is an indispensable cofactor in all domains of life, and its homeostasis must be regulated tightly. Here we report that a Nudix-related transcriptional factor, designated MsNrtR (MSMEG_3198), controls the pathway of NADbiosynthesis in , a non-tuberculosis . The integrated evidence and confirms that MsNrtR is an auto-repressor, which negatively controls the NADbiosynthetic pathway. Binding of MsNrtR cognate DNA is finely mapped, and can be disrupted by an ADP-ribose intermediate. Unexpectedly, we discover that the acetylation of MsNrtR at Lysine 134 participates in the homeostasis of intra-cellular NAD level in . Furthermore, we demonstrate that NrtR acetylation proceeds via the non-enzymatic acetyl-phosphate (AcP) route rather than by the enzymatic Pat/CobB pathway. In addition, the acetylation also occurs on the paralogs of NrtR in the Gram-positive bacterium and the Gram-negative bacterium , suggesting that these proteins have a common mechanism of post-translational modification in the context of NAD homeostasis. Together, these findings provide a first paradigm for the recruitment of acetylated NrtR to regulate bacterial central NAD metabolism.