Aspartate 1-decarboxylase (PanD) (PanD)

Aspartate 1-decarboxylase (PanD) and Ribosomal protein S1 (RpsA) are the primary molecular targets of pyrazinoic acid (POA), the active metabolite of the first-line antitubercular drug pyrazinamide (PZA) [2, 4, 8]. PZA is a prodrug that requires activation by the Mycobacterium tuberculosis enzyme pyrazinamidase (PncA) [3, 10]. Once activated, POA inhibits PanD by binding to it and triggering its degradation through the ClpC1-ClpP protease system, which depletes the cell of coenzyme A (CoA), an essential cofactor for metabolism [8, 13]. Additionally, POA binds to RpsA to inhibit trans-translation, a vital mechanism for protein synthesis quality control and ribosome recycling, particularly in non-replicating 'persister' bacilli [15]. The drug's unique ability to kill these dormant bacteria in acidic environments makes it indispensable for shortening the duration of tuberculosis treatment [2, 14]. Resistance is most commonly associated with mutations in the pncA gene, which prevent the activation of the prodrug, though mutations in panD and rpsA also contribute to resistance in some clinical isolates [2, 17].

Other names

Ribosomal protein S1RpsAPyrazinamidase/nicotinamidasePncANicotinamidaseFatty acid synthase IFAS-I

Pyrazinamide is a prodrug that is converted into its active form, pyrazinoic acid (POA), by the bacterial enzyme pyrazinamidase (PncA) [2, 3]. POA exerts its antibacterial effects through multiple mechanisms: it binds to aspartate 1-decarboxylase (PanD) and triggers its degradation via the ClpC1-ClpP protease complex, thereby inhibiting coenzyme A (CoA) biosynthesis [8]; it binds to ribosomal protein S1 (RpsA) to inhibit trans-translation, a process essential for rescuing stalled ribosomes [15]; and it acts as a protonophore to disrupt the bacterial membrane potential and acidify the cytoplasm [11, 12].