A FtsZ Inhibitor That Can Utilize Siderophore-Ferric Iron Uptake Transporter Systems for Activity against Gram-Negative Bacterial Pathogens.

The global threat of multidrug-resistant Gram-negative bacterial pathogens necessitates the development of new and effective antibiotics. FtsZ is an essential and highly conserved cytoskeletal protein that is an appealing antibacterial target for new antimicrobial therapeutics. However, the effectiveness of FtsZ inhibitors against Gram-negative species has been limited due in part to poor intracellular accumulation. To address this limitation, we have designed a FtsZ inhibitor () that incorporates a chlorocatechol siderophore functionality that can chelate ferric iron (Fe) and utilizes endogenous siderophore uptake pathways to facilitate entry into Gram-negative pathogens. We show that is active against both and , with this activity being dependent on direct Fe chelation and enhanced under Fe-limiting conditions. Genetic deletion studies in reveal that gains entry through the FepA and CirA outer membrane transporters and the FhuBC inner membrane transporter. We also show that exhibits bactericidal synergy against when combined with select antibiotics, with the strongest synergy observed with PBP2-targeting β-lactams or MreB inhibitors. In the aggregate, our studies indicate that incorporation of Fe-chelating moieties into FtsZ inhibitors is an appealing design strategy for enhancing activity against Gram-negative pathogens of global clinical significance.