Folate Pathway Disruption Leads to Critical Depletion of Methionine Derivatives in Mycobacterium tuberculosis

In this study, screening efforts identified novel antifolates with potent, targeted activity against whole cell Mycobacterium tuberculosis. Liquid chromatography-mass spectrometry analysis of antifolate-treated cultures revealed unique metabolic disruption, including decreased pools of methionine and S-adenosylmethionine. Transcriptomic analysis highlighted up-regulation genes involved in the biosynthesis and utilization of methionine. Supplementation with amino acids or methionine derivatives was sufficient to rescue cultures from MIC-level antifolate treatment. Instead of the “thymineless death” that characterizes folate pathway inhibition in a wide variety of organisms, these data suggest that M. tuberculosis is vulnerable to a critical disruption of the biosynthesis of methionine-derived compounds. These arrays look at the expression profile triggered by exposure to three different anti-folates (WR99210, dimethyl and diethyl methotrexate) in three biological replicates and in a matched set of untreated samples.