Disruption of Periplasmic Chaperone–OmpF Interaction as an Efficient Antibacterial Strategy against Gram-Negative Bacteria

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 <i>Escherichia coli</i> 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 <i>E. coli</i> 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., <i>Pseudomonas aeruginosa</i>, <i>Klebsiella pneumoniae</i>, <i>Acinetobacter baumannii</i>, and <i>Salmonella typhimurium</i>) and multidrug-resistant clinical isolates of <i>E. coli</i> 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.