As multidrug resistant pathogenic microorganisms are a serious health menace, it is crucial to continuously develop novel medicines in order to overcome the emerging resistance. The methylerythritol phosphate pathway (MEP) is an ideal target for antimicrobial development as it is absent in humans but present in most bacteria and in the parasite Plasmodium falciparum. Here, we report the synthesis and the steady-state kinetics of a novel potent inhibitor (MEPN3) of Escherichia coli YgbP/IspD, the third enzyme of the MEP pathway. MEPN3 inhibits E. coli YgbP/IspD in mixed type mode regarding both substrates. Interestingly, MEPN3 shows the highest inhibitory activity when compared to known inhibitors of E. coli YgbP/IspD. The mechanism of this enzyme was also studied by steady-state kinetic analysis and it was found that the substrates add to the enzyme in sequential manner.