Siderophore-Mediated Conveyance of Antibacterial-Antisense Oligomers

Antibacterial resistance is a major threat for human health. There is a need for new antibacterials to stay ahead of constantly-evolving resistant bacteria. Antibiotic antisense oligomers hold promise as powerful next-generation antibiotics, but issues with their delivery hamper their applicability. Here, we exploit the siderophore-mediated iron uptake pathway to efficiently transport antisense oligomers into bacteria. We appended a synthetic siderophore to antisense oligomers targeting the essential acpP gene in Escherichia coli. Siderophore-conjugated morpholino and PNA antisense oligomers displayed potent antibacterial properties. Conjugates bearing a minimal siderophore consisting of a mono-catechol group showed equally effective. Targeting the lacZ transcript resulted in dose-dependent decreased β-galactosidase production, demonstrating selective protein downregulation. Whole-genome sequencing of resistant mutants and competition experiments with the endogenous siderophore verified selective uptake through the siderophore-mediated iron uptake pathway. Lastly, no toxicity towards mammalian cells was found. Collectively, our work provides a convenient approach for delivering antisense oligomers into bacteria.