Enduracidin is a 17 amino acid lipopeptide antibiotic produced by the soil bacterium Streptomyces fungicidicus. Enduracidin was first discovered in the 1960’s, and there has been renewed interest in the compound with the rise in antibiotic resistance. Enduracidin is highly effective against many Gram-positive bacteria, including vancomycin-resistant Enterococcus faecium (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). Enduracidin is structurally very similar to ramoplanin, which is currently in late stage clinical trials for intestinal VRE and nasal MRSA. Enduracidin binds to extracellular Lipid II and inhibits the transglycosylation step in cell wall biosynthesis. These substrate-binding inhibitors block the ability of transglycosylase to catalyze the elongation step of peptidoglycan formation. This mechanism is analogous to the vancomycin mode of action but enduracidin recognizes the disaccharide/diphosphate element of Lipid II. There has been no reported resistance to enduracidin or ramoplanin.

We recently cloned and sequenced the enduracidin biosynthetic gene cluster. To explore the in vivo stepwise enzymatic functions leading to the antibiotic enduracidin, and to create enduracidin derivatives via genetic manipulation of the targeted genes, we have constructed a series of mutant strains by the insertional inactivation or in-frame deletion. Novel enduracidin analogs, including tetrahydroenduracidins and deschloroenduracidins, produced from these mutant strains will be presented. Utilization and operation of the created mutants in combinatorial biosynthesis for anti-superbugs drug development will be outlined and discussed.