Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/134714
Title: PYRAZINAMIDE RESISTANCE IS CAUSED BY TWO DISTINCT MECHANISMS: PREVENTION OF COENZYME A DEPLETION AND LOSS OF VIRULENCE FACTOR SYNTHESIS
Authors: POOJA GOPAL
Keywords: tuberculosis, pyrazinamide, pyrazinoic acid, resistance, phthiocerol dimycocerosate, coenzyme A
Issue Date: 28-Jul-2016
Source: POOJA GOPAL (2016-07-28). PYRAZINAMIDE RESISTANCE IS CAUSED BY TWO DISTINCT MECHANISMS: PREVENTION OF COENZYME A DEPLETION AND LOSS OF VIRULENCE FACTOR SYNTHESIS. ScholarBank@NUS Repository.
Abstract: Pyrazinamide (PZA) is a critical component of tuberculosis (TB) treatment regimen, yet its mechanism of action largely remains an enigma. Contrary to popular belief that PZA functions only at an acidic pH, we demonstrate here that both PZA and its active component pyrazinoic acid (POA) can inhibit growth of M. tuberculosis at neutral pH. Under these conditions, we carried out a genetic screen to isolate mutants resistant to pyrazinoic acid (POA), the bioactive derivative of PZA, followed by whole genome sequencing. Rather than finding mutations in proposed targets of PZA, we found resistance conferring mutations in two pathways: missense mutations in aspartate decarboxylase panD, involved in synthesis of the essential acyl carrier coenzyme A (CoA), and frameshift mutations in the polyketide synthase genes mas and ppsA-E, involved in the synthesis of the virulence factor phthiocerol dimycocerosate (PDIM). Probing the coenzyme A mechanism of action, we find that upon exposure to POA, the coenzyme A pathway collapsed downstream of the PanD-catalysed step, making PanD the first genetically, metabolically and biochemically validated target of PZA/POA.
URI: http://scholarbank.nus.edu.sg/handle/10635/134714
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