Exploring Structure-Activity Relationships and Modes of Action of Laterocidine.

A significant increase in life-threatening infections caused by Gram-negative "superbugs" is a serious threat to global health. With a dearth of new antibiotics in the developmental pipeline, antibiotics with novel mechanisms of action are urgently required to prevent a return to the preantibiotic era. A key strategy to develop novel anti-infective treatments is to discover new natural scaffolds with distinct mechanisms of action. Laterocidine is a unique cyclic lipodepsipeptide with activity against multiple problematic multidrug-resistant Gram-negative pathogens, including Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacterales. Here, we developed a total chemical synthesis methodology for laterocidine and undertook systematic structure-activity relationship studies with chemical biology and NMR. We discovered important structural features that drive the antimicrobial activity of laterocidine, leading to the discovery of an engineered peptide surpassing the efficacy of the original peptide. This engineered peptide demonstrated complete inhibition of the growth of a polymyxin-resistant strain of Pseudomonas aeruginosa in static time-kill experiments.