Investigating Novel IspE Inhibitor of MEP Pathway in Mycobacterium

In a recent effort to mitigate harm from human pathogens, many biosynthetic pathways are extensively evaluated for their ability to inhibit pathogen growth and determine drug targets. Among those, one of the important products/targets of such pathways is isopentenyl diphosphate, the universal precursor of isoprenoids, which are essential for the normal functioning of microorganisms. In general, two biosynthetic pathways lead to the formation of isopentenyl diphosphate: 1) the mevalonate pathway in animals and 2) the non-mevalonate or methylerythritol phosphate (MEP) in many bacteria, some protozoa, and plants. Because the MEP pathway is not found in mammalian cells, it is considered an attractive target for the development of antimicrobials against a variety of human pathogens, including Mycobacterium tuberculosis (M.tb). In the MEP pathway, 4-diphosphocytidyl-2-c-methyl-d-erythritol kinase (IspE) phosphorylates 4-diphosphocytidyl-2-C-methyl-D-erythritol (CDPME) to form 4-diphosphocytidyl-2-C-methyl-D-erythritol 2-phosphate (CDPME2P), followed by cyclization to 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MECPP) by 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (IspF). A virtual high throughput screening was done by docking IspE protein with commercially available compounds and identified an active heterotricyclic compound. Hence, we designed, synthesized, and tested similar new heterotricyclic compounds. This study will provide the critical insight necessary for the ability to develop novel antimicrobials that target the MEP pathways in pathogens.