Mycobacterium tuberculosis isocitrate lyase (ICL) isoforms 1 and 2 are critical metabolic enzymes that enable virulence and survival by acting as gatekeepers at the junction between the glyoxylate shunt and the TCA cycle.1,2,3 Details about the regulation and modulation of ICLs at the protein level is significant, as the direction of carbon flow between these two key metabolite pathways may enable the development of new treatments against tuberculosis.4 Herein, we report our work on the modulation of ICLs from structural and mechanistic perspectives by using X-ray crystallography, NMR spectroscopy, mutagenesis and kinetic studies. Our results provide new fundamental knowledge about the control of the central carbon metabolism in M. tuberculosis.