Pyrazinamide inhibits the eukaryotic-like fatty acid synthetase I (FASI) of Mycobacterium tuberculosis

Zimhony, Oren; Cox, Jeffery S.; Welch, John T.; Vilchèze, Catherine; Jacobs, William R.

doi:10.1038/79558

Cited by 231 publications

(198 citation statements)

References 31 publications

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“…The mycobacterial FASII system is incapable of de novo fatty acid synthesis but instead elongates acyl primers (C 16 -26 ) to larger mycolic acid intermediates (38). For this reason, purified KasA and KasB activities were initially tested using C 16:0 acyl substrates.…”

Section: Figmentioning

confidence: 99%

Purification and Biochemical Characterization of theMycobacterium tuberculosis β-Ketoacyl-acyl Carrier Protein Synthases KasA and KasB

Schaeffer¹,

Agnihotri²,

Volker³

et al. 2001

Journal of Biological Chemistry

140

130

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Mycolic acids are vital components of the Mycobacterium tuberculosis cell wall, and enzymes involved in their formation represent attractive targets for the discovery of novel anti-tuberculosis agents. Biosynthesis of the fatty acyl chains of mycolic acids involves two fatty acid synthetic systems, the multifunctional polypeptide fatty acid synthase I (FASI), which performs de novo fatty acid synthesis, and the dissociated FASII system, which consists of monofunctional enzymes, and acyl carrier protein (ACP) and elongates FASI products to long chain mycolic acid precursors. In this study, we present the initial characterization of purified KasA and KasB, two ␤-ketoacyl-ACP synthase (KAS) enzymes of the M. tuberculosis FASII system. KasA and KasB were expressed in E. coli and purified by affinity chromatography. Both enzymes showed activity typical of bacterial KASs, condensing an acyl-ACP with malonyl-ACP. Consistent with the proposed role of FASII in mycolic acid synthesis, analysis of various acyl-ACP substrates indicated KasA and KasB had higher specificity for long chain acyl-ACPs containing at least 16 carbons. Activity of KasA and KasB increased with use of M. tuberculosis AcpM, suggesting that structural differences between AcpM and E. coli ACP may affect their recognition by the enzymes. Both enzymes were sensitive to KAS inhibitors cerulenin and thiolactomycin. These results represent important steps in characterizing KasA and KasB as targets for antimycobacterial drug discovery.

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Section: Figmentioning

confidence: 99%

Purification and Biochemical Characterization of theMycobacterium tuberculosis β-Ketoacyl-acyl Carrier Protein Synthases KasA and KasB

Schaeffer¹,

Agnihotri²,

Volker³

et al. 2001

Journal of Biological Chemistry

140

130

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“…It has been shown that acid pH enhances the uptake and accumulation of POA in M. tuberculosis, which has been shown to have a defective ef¯ux mechanism for POA [15]. While the target of POA is thought to be fatty acid synthesis pathway 1 [16], POA as a weak acid could potentially kill tubercle bacilli through recycling of POA leading to de-energised membrane as a possible mechanism of action [17].…”

Section: Introductionmentioning

confidence: 99%

Conditions that may affect the results of susceptibility testing of Mycobacterium tuberculosis to pyrazinamide

Zhang

Permar

Sun

2002

Journal of Medical Microbiology

211

198

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Pyrazinamide (PZA) is an important front-line anti-tuberculosis drug that is active only at acid pH. However, acid pH causes signi®cant dif®culty for PZA susceptibility testing. A common problem in PZA testing is false resistance caused by large bacterial inocula. This study investigated the relationship of false resistance to numbers of bacilli, pH and other factors that potentially affect susceptibility to PZA. Large inocula (10 7±8 bacilli=ml) of M. tuberculosis H37Ra caused signi®cant increase in medium pH from 5.5 towards neutrality, and thus produced false resistance results. The increase in medium pH was determined to be a function of live bacilli; heat-killed bacilli had little or no effect. Susceptibility to PZA and its active derivative pyrazinoic acid (POA) was comparable on 7H11 agar medium, but POA was less active than PZA in liquid medium containing bovine serum albumin (BSA), suggesting that susceptibility to PZA or POA was reduced in the presence of BSA, because of its neutralising effect on medium pH and signi®cant POA binding. A 3-month-old H37Ra culture was shown to be more susceptible to PZA exposure than a 4-day log-phase culture, suggesting that PZA is more active for non-growing bacilli. Finally, reserpine, an inhibitor of POA ef¯ux pump, increased susceptibility to PZA even near neutral pH 6.8, with an MIC of 400 mg=L compared with 1000 mg=L without reserpine. These ®ndings should have implications for understanding the mode of action of PZA and for PZA susceptibility testing.

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“…80,81 The major mechanism of PZA resistance in Mtb described in the literature is mutation in its activator gene pncA [82][83][84][85][86][87][88][89] . In an effort to overcome resistance and enhancing PZA activity, scientists have derivatized pyrazinamide in different ways.…”

Section: Isoniazid As Targetmentioning

confidence: 99%

Untitled

2017

IJPSR

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Tuberculosis (TB) remains one of the main causes of death from an infectious disease till date. Recent data shows that currently 9.6 million people are infected with TB. Over 95% of TB deaths occur in low-and middle-income countries and it is among the top 5 causes of death for women aged 15 to 44. TB is a leading killer of HIV-positive people and around 1 in 3HIV deaths was due to TB. Furthermore, multidrug-resistant (MDR)-TB and extensively drug-resistant (XDR)-TB is spreading and poses a major threat to progress in global TB control program. The emergence of drug resistant TB strains makes the invention of new molecular scaffold a priority. One of the possible strategies to overcome drug resistance in an economic and simple manner would involve re-engineering and repositioning of some old drugs to obtain derivatives that can work on resistant TB bacilli. These may have enhanced bioavailability, be more effective, and serve as cost-effective substitutes, as compared to new drugs identified through conventional methods of drug discovery and development. In view of this, the present review aims to provide a summarizing report on the derivatives of firstline drugs (isoniazid and pyrazinamide) that have the potential to conquer the resistance to the parental drug and could thus serve as effective alternatives.

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Pyrazinamide inhibits the eukaryotic-like fatty acid synthetase I (FASI) of Mycobacterium tuberculosis

Cited by 231 publications

References 31 publications

Purification and Biochemical Characterization of theMycobacterium tuberculosis β-Ketoacyl-acyl Carrier Protein Synthases KasA and KasB

Purification and Biochemical Characterization of theMycobacterium tuberculosis β-Ketoacyl-acyl Carrier Protein Synthases KasA and KasB

Conditions that may affect the results of susceptibility testing of Mycobacterium tuberculosis to pyrazinamide

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