Pyrazinoic Acid Inhibits Mycobacterial Coenzyme A Biosynthesis by Binding to Aspartate Decarboxylase PanD

ACS Infect Dis. 2017 Nov 10;3(11):807-819. doi: 10.1021/acsinfecdis.7b00079. Epub 2017 Oct 18.


Previously, we showed that a major in vitro and in vivo mechanism of resistance to pyrazinoic acid (POA), the bioactive component of the critical tuberculosis (TB) prodrug pyrazinamide (PZA), involves missense mutations in the aspartate decarboxylase PanD, an enzyme required for coenzyme A biosynthesis. What is the mechanism of action of POA? Upon demonstrating that treatment of M. bovis BCG with POA resulted in a depletion of intracellular coenzyme A and confirming that this POA-mediated depletion is prevented by either missense mutations in PanD or exogenous supplementation of pantothenate, we hypothesized that POA binds to PanD and that this binding blocks the biosynthetic pathway. Here, we confirm both hypotheses. First, metabolomic analyses showed that POA treatment resulted in a reduction of the concentrations of all coenzyme A precursors downstream of the PanD-mediated catalytic step. Second, using isothermal titration calorimetry, we established that POA, but not its prodrug PZA, binds to PanD. Binding was abolished for mutant PanD proteins. Taken together, these findings support a mechanism of action of POA in which the bioactive component of PZA inhibits coenzyme A biosynthesis via binding to aspartate decarboxylase PanD. Together with previous works, these results establish PanD as a genetically, metabolically, and biophysically validated target of PZA.

Keywords: aspartate decarboxylase; coenzyme A; pyrazinamide; pyrazinoic acid; tuberculosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antitubercular Agents / pharmacology*
  • Binding Sites
  • Carbon / metabolism
  • Carboxy-Lyases / antagonists & inhibitors*
  • Coenzyme A
  • Gene Expression Regulation, Bacterial / drug effects
  • Gene Expression Regulation, Enzymologic / drug effects
  • Models, Molecular
  • Mycobacterium bovis / drug effects
  • Mycobacterium tuberculosis / enzymology*
  • NAD / biosynthesis
  • Protein Binding
  • Protein Conformation
  • Pyrazinamide / analogs & derivatives*
  • Pyrazinamide / pharmacology


  • Antitubercular Agents
  • NAD
  • Pyrazinamide
  • pyrazinoic acid
  • Carbon
  • Carboxy-Lyases
  • Coenzyme A