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Aspartate decarboxylase (PanD) as a new target of pyrazinamide in Mycobacterium tuberculosis.

ABSTRACT: Pyrazinamide (PZA) is a frontline anti-tuberculosis drug that plays a crucial role in the treatment of both drug-susceptible and multidrug-resistant tuberculosis (MDR-TB). PZA is a prodrug that is converted to its active form, pyrazinoic acid (POA), by a nicotinamidase/pyrazinamidase encoded by the pncA gene, the mutation of which is the major cause of PZA resistance. Although RpsA (ribosomal protein S1, involved in trans-translation) has recently been shown to be a target of POA/PZA, whole-genome sequencing has identified mutations in the panD gene encoding aspartate decarboxylase in PZA-resistant strains lacking pncA and rpsA mutations. To gain more insight into a possible new target of PZA, we isolated 30 POA-resistant mutants lacking mutations in pncA and rpsA from M. tuberculosis in vitro, and whole-genome sequencing of 3 mutants identified various mutations in the panD gene. Additionally, sequencing analysis revealed that the remaining 27 POA-resistant mutants all harbored panD mutations affecting the C-terminus of the PanD protein, with PanD M117I being the most frequent mutation (24/30, 80%). Conditional overexpression of panD from M. tuberculosis, M. smegmatis or E. coli, or of M. tuberculosis mutant PanD M117I, all conferred resistance to POA and PZA in M. tuberculosis. ?-alanine and pantothenate, which are downstream products of PanD, were found to antagonize the antituberculosis activity of POA. In addition, the activity of the M. tuberculosis PanD enzyme was inhibited by POA at therapeutically relevant concentrations in a concentration-dependent manner but was not inhibited by the prodrug PZA or the control compound nicotinamide. These findings suggest that PanD represents a new target of PZA/POA. These results have implications for a better understanding of this peculiar persister drug and for the design of new drugs targeting M. tuberculosis persisters for improved treatment.

SUBMITTER: Shi W

PROVIDER: S-EPMC4150287 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Aspartate decarboxylase (PanD) as a new target of pyrazinamide in Mycobacterium tuberculosis.

Shi Wanliang W Chen Jiazhen J Feng Jie J Cui Peng P Zhang Shuo S Weng Xinhua X Zhang Wenhong W Zhang Ying Y

Emerging microbes & infections 20140813 8

Pyrazinamide (PZA) is a frontline anti-tuberculosis drug that plays a crucial role in the treatment of both drug-susceptible and multidrug-resistant tuberculosis (MDR-TB). PZA is a prodrug that is converted to its active form, pyrazinoic acid (POA), by a nicotinamidase/pyrazinamidase encoded by the pncA gene, the mutation of which is the major cause of PZA resistance. Although RpsA (ribosomal protein S1, involved in trans-translation) has recently been shown to be a target of POA/PZA, whole-geno ...[more]

PMID: 26038753

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Project description:UNLABELLED:Coenzyme A (CoA) is essential for cellular chemistry in all forms of life. The pantothenate moiety of CoA is generated from the condensation of pantoate and ?-alanine. ?-Alanine is formed by decarboxylation of l-aspartate catalyzed by PanD, a pyruvoyl enzyme that is synthesized by the cell as an inactive precursor (pro-PanD). Maturation of pro-PanD into PanD occurs via a self-cleavage event at residue Ser25, which forms the catalytic pyruvoyl moiety. We recently reported that Salmonella enterica PanM was necessary for pro-PanD maturation, both in vitro and in vivo. Notably, PanM is annotated as a Gcn5-like N-acetyltransferase (GNAT), which suggested that lysine acetylation might be part of the mechanism of maturation. Here we show that PanM lacks acetyltransferase activity and that acetyl-CoA stimulates its activity. Results of experiments with nonhydrolyzable ethyl-CoA and genetically encoded acetyl-lysine-containing PanD support the conclusion that PanM-dependent pro-PanD maturation does not involve an acetyl transfer event. We also show that CoA binding to PanM is needed for in vivo activity and that disruption of CoA binding prevents PanM from interacting with PanD. We conclude that PanM is a GNAT homologue that lost its acetyltransferase activity and evolved a new function as an acetyl-CoA sensor that can trigger the maturation of pro-PanD. IMPORTANCE:N?-lysine acetylation is increasingly being recognized as a widespread and important form of posttranslational regulation in bacteria. The acetyltransferases that catalyze these reactions are poorly characterized in bacteria. Based on annotation, most bacterial genomes contain several acetyltransferases, but the physiological roles of only a handful have been determined. Notably, a subset of putative acetyltransferases lack residues that are critical for activity in most biochemically characterized acetyltransferases. We show that one such putative acetyltransferase, PanM (formerly YhhK), lacks acetyltransferase activity but functions instead as an acetyl-coenzyme A (CoA) sensor. This work establishes the possibility that, like PanM, other putative acetyltransferases may have evolved new functions while retaining the ability to sense acetyl-CoA.

Dataset Information

Aspartate decarboxylase (PanD) as a new target of pyrazinamide in Mycobacterium tuberculosis.

Publications

Aspartate decarboxylase (PanD) as a new target of pyrazinamide in Mycobacterium tuberculosis.

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