Modification of drug-binding proteins associated with the efflux pump in MDR-MTB in course of evolution: an unraveled clue based on in silico approach.

Abstract

Mycobacterium tuberculosis (MTB) is commonly resistant to various drugs. Multidrug-resistant tuberculosis (MDR-MTB) is mostly caused by mutation in drug-binding proteins and protein folding. The aim of the study was to identify the pattern of mutations in embC, inhA and rpoB proteins and investigate its interactions with available drug such as rifampicin, ethambutol and isoniazid, using a computer docking method. The evolution of drugs resistant mechanisms of MTB was analyzed using an in silico approach. The model proteins were considered to be in a protein-protein interaction network among the twenty transmembrane proteins. The changes in structural conformation may describe the significance of the proton pumps system. The docking analysis revealed that unlike isoniazid, both rifampicin and ethambutol, bound to the same residues in mutant and wild forms. Moreover, multiple-sequence alignment (MSA) showed mutational hotspot regions where the substitution of amino acids in these three target proteins was position specific under stress. The molecular basis of drug resistance in M. tuberculosis can be represented by a protein network which is a well-regulated system for efflux pump activation by popularly used drugs. Ethambutol and rifampicin form stable complexes with EmbC and RpoB, respectively. Isoniazid shows no binding affinity to mutant InhA (2015). Analysis of the cellular network associated with drug regulatory proteins suggest that mmpl3, Rv1634 and Rv1258c play a major role by altering the protein pump to remove the active drug compounds from the bacterial cell.