Discovery and Derivatization of Tridecaptin Antibiotics with Altered Host Specificity and Enhanced Bioactivity.

The prevalence of multidrug-resistant (MDR) pathogens combined with a decline in antibiotic discovery presents a major challenge for health care. To refill the discovery pipeline, we need to find new ways to uncover new chemical entities. Here, we report the global genome mining-guided discovery of new lipopeptide antibiotics tridecaptin A5 and tridecaptin D, which exhibit unusual bioactivities within their class. The change in the antibacterial spectrum of Oct-TriA5 was explained solely by a Phe to Trp substitution as compared to Oct-TriA1, while Oct-TriD contained 6 substitutions. Metabolomic analysis of producer Paenibacillus sp. JJ-21 validated the predicted amino acid sequence of tridecaptin A5. Screening of tridecaptin analogues substituted at position 9 identified Oct-His9 as a potent congener with exceptional efficacy against Pseudomonas aeruginosa and reduced hemolytic and cytotoxic properties. Our work highlights the promise of tridecaptin analogues to combat MDR pathogens.

Targeting membrane-bound bacterial cell wall precursors: a tried and true antibiotic strategy in nature and the clinic.

Since Fleming's discovery of penicillin nearly a century ago, a bounty of natural product antibiotics have been discovered, many of which continue to be of clinical importance today. The structural diversity encountered among nature's repertoire of antibiotics is mirrored by the varying mechanisms of action by which they selectively target and kill bacterial cells. The ability for bacteria to construct and maintain a strong cell wall is essential for their robust growth and survival under a range of conditions. However, the need to maintain the cell wall also presents a vulnerability that is exploited by many natural antibiotics. Bacterial cell wall biosynthesis involves both the construction of complex membrane-bound precursor molecules and their subsequent crosslinking by dedicated enzymes. Interestingly, many naturally occurring antibiotics function not by directly inhibiting the enzymes associated with cell wall biosynthesis, but rather by binding tightly to their membrane-bound substrates. Such substrate sequestration mechanisms are comparatively rare outside of the antibiotics space with most small-molecule drug discovery programs instead aimed at developing inhibitors of target enzymes. In this feature article we provide the reader with an overview of the unique and ever increasing family of natural product antibiotics known to specifically function by binding to membrane-anchored bacterial cell wall precursors. In doing so, we highlight both our own contributions to the field as well as those made by other researchers engaged in exploring the potential offered by antibiotics that target bacterial cell wall precursors.