The escalating global crisis of antibiotic resistance demands the urgent development of innovative antibacterial agents with new mechanisms of action. Herein, we report the design and characterization of self-derived antibacterial peptides from the N-terminal region of Escherichia coli OmpF, a typical β-barrel outer membrane protein (OMP). These peptides exhibit cellular lethality when endogenously expressed, and one of them, having 42 amino acids in length (designated as OmpF7), directly kills outer membrane-permeabilized E. coli cells. Mechanistically, OmpF7 interacts with periplasmic chaperones SurA and Skp in vitro, disrupts both in vitro and in vivo SurA-OmpF interactions, decreases the level of folded OmpF, and severely influences cell morphology but has little detrimental effect on the cytoplasmic membrane and behaves distinctively from polymyxin B, a well-known antibacterial peptide. Importantly, OmpF7 directly kills Gram-negative pathogens (e.g., Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, and Salmonella typhimurium) and multidrug-resistant clinical isolates of E. coli when it is conjugated with a membrane-penetrating peptide or combined with a nontoxic adjuvant carvacrol. These observations suggest that OmpF7 exerts its lethal effects by saturating the OMP-binding sites of SurA/Skp and thus disrupting chaperone-mediated OMP biogenesis, eventually leading to cell death. Our study not only validates periplasmic chaperone-OMP interactions as promising drug targets against Gram-negative pathogens but also provides a chemical biology tool for probing the OMP biogenesis mechanism.
Wang et al. (Thu,) studied this question.