Darobactin (DAR) and dynobactin (DYN) are Ribosomally synthesized and Posttranslationally modified Peptides (RiPPs). These compounds exhibit a broad spectrum anti-Gram-negative antibiotic activity by inhibiting the Bam complex responsible for the assembly of outer membrane proteins in Gram-negative bacteria. Recently, we successfully characterized the functions and mechanisms of the radical SAM enzymes responsible for their biosynthesis. Specifically, we found that DarE radical SAM enzyme catalyzes the formation of the ether crosslink formation in darobactins using O2 as a co-substrate (JACS 2023). This finding significantly impacted the field because radical SAM enzymes were thought to function only under strictly anaerobic conditions. We are currently studying the details of the mechanisms and structures of these enzymes with the goal of developing more effective anti-Gram-negative antibiotics.
