Differential expression of the Mycobacterium tuberculosis heat shock protein genes in response to drug-induced stress

Heat shock proteins are essential in maintaining cellular protein function, especially during stress. Their influence in managing drug-induced stress in Tuberculosis is not clearly understood. Study the expression of select genes of the DnaK/ClpB chaperone network to evaluate their role in stress response in Mycobacterium tuberculosis clinical isolates during exposure to Isoniazid (INH) and Rifampicin (RIF). Sanger sequencing to detect drug-resistant mutations followed by Drug Susceptibility Testing and Minimum Inhibitory Concentration determination. Culturing the bacilli in vitro, exposed to 1/4, 1/2 and 1 × MIC, and RNA quantification of dnaK, dnaJ1, grpE and clpB genes by using Real-time PCR. Susceptible isolates showed marginal down-regulation of two genes for INH, whereas all genes under-expressed against RIF. INH-resistant isolates had distinct expression profiles for inhA-15 and katG315 mutants. RIF-resistant bacilli did not have significant differential expression. MDR isolate showed up-regulation of all the four genes, with two genes over-expressing (≥4-fold). We observed characteristic gene expression profiles for each isolate in response to lethal and sub-lethal doses of INH and RIF. This provides insight into the role of DnaK/ClpB chaperone network in managing drug-induced stress and facilitating resistance. Further, the knowledge could provide targets for new drugs and augmenters. •Role of DnaK/ClpB chaperone network in managing drug-induced stress in Tuberculosis.•HSP gene expression in katG-mutant Mycobacterium correlated to drug dosage.•DnaK/ClpB linked pathway not triggered in RIF-resistant isolate on drug exposure.•Over-expression of dnaK and grpE in INH/RIF treated MDR Tuberculosis isolate.