Methionine and Iron Supplementation Enhances Kanamycin Activity Against Mycobacterium tuberculosis

Despite understanding the functional roles of important proteins in sulfate assimilation and trans-sulfuration pathways, no study has been conducted to estimate the changes in the intracellular thiol levels when mycobacterium is treated with methionine. Methionine was known to be sulfur source for mycobacteria when it resides in the hostile granuloma environment and through transsufuration pathway methionine was shown to stimulate the sulfate assimilation. To study the dynamics of sulfate assimilation pathway we created gene knockout strains of important enzymes in the sulfate assimilation pathway of M. smegmatis. We stimulated these mutants with methionine, pro-filed the changes in intracellular thiols, applied external oxidative stress, and monitored the associated intracellular redox potentials (EMSH). These experiments revealed that when M. smegmatis cultures are supplemented with methionine intracellular levels surged. When those cells were challenged with hydrogen peroxide the M. smegmatis cells showed increased intracellular oxidative potentials and took prolonged time to revert back normal redox balance state when compared to non-methionine containing controls. Here in this report, we are describe how the dynamic changes of intracellular thiols are linked to augment the activity of kanamycin.