Inhibitors of Mycobacterium tuberculosis methionyl-tRNA synthetase are sensitive to the mutations E24A and L293A in aminoacyl-adenylate binding site

The objective of this study was to obtain Mycobacterium tuberculosis methionyl-tRNA synthetase (MetRS) mutant forms E24A and L293A and investigate the efficiency of M. tuberculosis MetRS inhibitors toward these mutant forms in order to predict binding mechanisms. The recombinant mutant M. tuberculosis MetRS E24A and L293A were obtained using overlap PCR. The recombinant proteins MetRS E24A and L293A were expressed in BL21(DE3) cells. The activity of obtained aminoacyl-tRNA synthetases was studied with aminoacylation assay using BIOMOL® Green Reagent. It was found that the mutations of Glu24 and Leu293 with alanine in the synthetic site of M. tuberculosis MetRS lead to significant decrease of inhibitory activity of investigated compounds. These findings suggest that the amino acid residues Glu24 and Leu293 may contribute to the inhibitory activity of the studied compounds and should therefore be considered during further structural optimization.