2012
DOI: 10.1074/jbc.m111.333385
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A Novel Mechanism of Growth Phase-dependent Tolerance to Isoniazid in Mycobacteria

Abstract: Background:The mechanism underlying mycobacterial phenotypic tolerance to isoniazid is unknown. Results: MDP1, a mycobacterial histone-like protein, down-regulates KatG expression. Conclusion: Down-regulation of KatG by MDP1 causes growth phase-dependent phenotypic tolerance to isoniazid in mycobacteria. Significance: Understanding the mechanism by which mycobacteria acquire tolerance to isoniazid is important for developing novel therapies.

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Cited by 48 publications
(55 citation statements)
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“…Although the enoyl-acyl carrier protein reductase InhA is the most described, other mechanisms and enzymes may be involved, such as the human arylamine N-acetyltransferase (NAT) polymorphism, the TB NAT that is also required for mycolic acid synthesis, the MDP1 gene, or even the loss of a sigma factor (34)(35)(36)(37)(38). Mycobacterial NudC may also play an important role in the inactivation of INH (39).…”
Section: Discussionmentioning
confidence: 99%
“…Although the enoyl-acyl carrier protein reductase InhA is the most described, other mechanisms and enzymes may be involved, such as the human arylamine N-acetyltransferase (NAT) polymorphism, the TB NAT that is also required for mycolic acid synthesis, the MDP1 gene, or even the loss of a sigma factor (34)(35)(36)(37)(38). Mycobacterial NudC may also play an important role in the inactivation of INH (39).…”
Section: Discussionmentioning
confidence: 99%
“…Although M. tuberculosis can inhibit maturation of the phagosome and limit its acidification to a pH of ϳ6.2 by excluding vacuolar proton-ATPase in immunologically naive macrophages, this block is relieved and the phagosomal compartment acidifies to a pH of 4.5 to 5.0 in gamma interferon (IFN-␥)-activated macrophages (56). Importantly, exposure of M. tuberculosis to a pH of Ͻ5.5 in vitro leads to growth arrest (57,58) and phenotypic tolerance to isoniazid (59). The in vivo relevance of the acidic pH model of M. tuberculosis dormancy is underscored by the fact that pyrazinamide, which exhibits antituberculous activity only under acidic conditions (60), is highly active in combination with rifampin for the treatment of LTBI (3).…”
Section: Stresses Simulating the Environment Within The Macrophage Phmentioning
confidence: 99%
“…There are several mutations in different genes, but particularly in codon 315 of the katG gene, the inhA regulatory region and the ahpC-oxyR intergenic region which are associated with isoniazid resistance (Hazbon et al, 2006;Mokrousov et al, 2002;Blanchard, 1996;Gillespie, 2002). In the case of INH-resistant strains, the most common cause of resistance is a mutation in or the downregulation of the katG gene which reduces the rate at which the pro-drug converts into its active state (Rouse et al, 1995;Niki et al, 2012). One can describe the formation of the active drug as:…”
Section: Resultsmentioning
confidence: 99%
“…In the later stages of the disease, the model proposed here may not apply because INH has significantly lower effectiveness against non-replicating bacilli (Niki et al, 2012). Initially all bacilli have the same cell wall thickness.…”
Section: Mathematical Modelmentioning
confidence: 99%