IN SILICO ANALYSIS OF NOVEL MUTATION K96R IN M.TUBERCULOSIS PNCA: COMPUTATIONAL CHARACTERIZATION OF PYRAZINAMIDE DRUG RESISTANCE MECHANISM AND DEVELOPMENT OF NOVEL DRUG LEADS TO COMBAT MUTATIONS IN PNCA

Abstract

Pyrazinamide (PZA) is one of the most effective first line treatments against tuberculosis disease. The drug is capable of bacteriostatic action and also acts on bacterial spores which eliminate chances of resurfacing of the infection. However, in recent years the there has been a major increase in the occurrence of drug resistant bacterial strains. These mutations prevents drug binding to bacterial proteins and impart resistance. Resistance against PZA is caused by mutations in PncA protein which is the activator of the prodrug PZA. Resistance has been developed against many first and second line drugs and cases of Multi Drug Resistance are on the rise. In order to develop better drug therapies it is imperative to first understand the mechanism of action of these drug resistance causing mutations. In the present study, we have tried to gain insight into the mechanism of action of a novel mutation K96R occurring in the PncA catalytic region. For this purpose, binding cavity assessment was performed to identify the change in volume after mutation. This gives us an idea about how the ligand would be perceived in the cavity. This was followed by docking studies to analyse the binding of the ligand with the protein, binding energies, vander waal energies and electrostatic energies. Interaction networks of both native and mutant protein with PZA ligand were also analyzed. To identify the dynamic conformational changes in the complexes, molecular dynamic simulations were performed. These results helped in developing a combinatorial library of novel PZA derivatives. Later, virtual screening was performed with novel pyrazinamide derivatives to identify leads which were capable of binding with wild and various PncA mutants with greater efficacy than PZA.