Acetylation of Isoniazid Is a Novel Mechanism of Isoniazid Resistance in Mycobacterium tuberculosis

Abstract

Isoniazid (INH), one of the first-line drugs used for tuberculosis treatment, is a pro-drug which is activated by the intracellular KatG enzyme of Mycobacterium tuberculosis. The activated drug hinders cell wall biosynthesis by inhibiting InhA protein. INH resistant strains of M. tuberculosis usually have mutations in katG, inhA, ahpC, kasA, and ndh genes. However, INH resistant strains which do not have mutations in any of these genes are reported, suggesting that these strains may adopt some other mechanism to become resistant to INH. In the present study, we characterized Rv2170, a putative acetyltransferase in M. tuberculosis, to elucidate its role in inactivating isoniazid. The purified recombinant protein was able to catalyze the transfer of the acetyl group to INH from acetyl CoA. HPLC and LC-MS analyses showed that following acetylation by Rv2170, INH is broken down into isonicotinic acid and acetylhydrazine. Drug susceptibility assay and confocal analysis showed that M. smegmatis, which is susceptible to INH, is not inhibited by INH acetylated with Rv2170. Mutant proteins of Rv2170 failed to acetylate INH. Recombinant M. smegmatis and M. tuberculosis H37Ra overexpressing Rv2170 were found to be resistant to INH at minimum inhibitory concentrations that inhibited wildtype strains. Besides, intracellular M. tuberculosis H37Ra overexpressing Rv2170 survived better in macrophages when treated with INH. Our results strongly indicate that Rv2170 acetylates INH, and this could be one of the strategies adopted by at least some M. tuberculosis strains to overcome INH toxicity, although this needs to be tested in INH resistant clinical strains.

The Role of Phosphorylation and Acylation in the Regulation of Drug Resistance in Mycobacterium tuberculosis

“…In the present study, the putative acetyltransferase Rv2710 in MTB is reported to inactivate INH. The overexpression of Rv2710 in M. tuberculosis H37Ra leads to its resistance to INH at MICs [ 19 ].…”

“…The active INH Beta-ketoacyl-acyl carrier protein reductase (MabA) and NADH-specific enoyl acyl carrier protein reductase (InhA) are important enzymes associated with FAS-II [ 51 , 52 ]. The activated INH inhibits the InhA protein by binding to its active site which, in turn, hinders mycolic acid synthesis, and disturbs M. tuberculosis cell wall biosynthesis [ 19 ]. MabA and InhA can be phosphorylated by many kinds of STPKs, including PknB.…”

Phenylisoxazole-3/5-Carbaldehyde Isonicotinylhydrazone Derivatives: Synthesis, Characterization, and Antitubercular Activity

“…e characterization of a novel series of the phenylisoxazole-3/5-carbaldehyde isonicotinylhydrazone derivatives 1-8 was performed by using the 1D NMR ( 1 H-and 13 C-NMR) and 2D ( 1 H-1 H COSY, 1 H-1 H NOESY, 1 H- 13 C HSQC, and 1 H- 13 C HMBC) spectra, recorded in acetone-d 6 / DMSO-d 6 (see Supplementary [11][12][13][14][15]18,19,22,23,26,[28][29][30][31][32][34][35][36][37][38]41,and 42 in Supplementary Materials).…”

“…It is well known that the N-acetyltransferases (NATs) have been implicated in the resistance developed by "isoniazid, one of the first-line drugs in TB treatment" [1], due to the enzymatic acetylation of its primary amino group to form N-acetyl INH [2,[8][9][10][11][12]. In this sense, one of the benefits of isoniazid is obtaining a broad spectrum of novel isoniazid derivatives by condensing the terminal amine group (-NH 2 ) with the carbonyl group (-C�O) from aldehydes or ketones to produce new compounds with functional groups of the acylhydrazone type (∼CH�NH-NH-C�O∼) [13,14] that can act as bidentate ligands (N,O) and coordinate to transition metals to obtain bis-chelate complexes [15,16].…”

Isoniazid—Loaded Albumin Nanoparticles: Taguchi Optimization Method

“…If we classify drugs by activity, the most effective drugs are isoniazid (INH) and rifampicin (RIF). Isoniazid has been used since the beginning of the 20th century, and in some cases, MTB has mutated to become resistant to this drug, as it has to many other first-line drugs [7][8][9]. Multidrug resistance tuberculosis (MDR-TB)…”