The rise of multidrug-resistant (MDR) Escherichia coli has marginalized last-line polymyxins (PMs) owing to evolving resistance and narrow therapeutic windows. Revitalizing these agents requires the identification of novel regulatory circuits governing the integrity of the gram-negative envelope. In this study, we identified TimP, a stress-responsive peptide, and demonstrated that intracellular overexpression (TimP+), synthetic peptide (FT-Pep), and biogenic TimP+-derived extracellular vesicles (TimP EVs) exhibited equivalent functionality in sensitizing E. coli to PMs with PM-mediated phenotypes. Mechanistically, TimP in E. coli initiates coordinated envelope remodeling by interacting with porin LamB via a specific N21TimP-R134 LamB molecular interface. Furthermore, the TimP-TimR/TimP-LamB interaction is functionally conserved in both E. coli and Salmonella. Pharmacokinetic profiling and spatiotemporal imaging of FT-Pep revealed a predictable physiological disposition across major organs and gradual systemic clearance over 24 h, with no evidence of pathological sequestration. Hepatic and immunological assessments confirmed that FT-Pep or TimP EVs were systemically inert, with serum pro-inflammatory markers and liver enzymes remaining within baseline physiological ranges. Exploiting these beneficial effects, we engineered polymyxin B (PMB)@TimP EVs, which exhibited enhanced bactericidal activity, improved pH stability, and negligible mammalian cytotoxicity compared with free PMB. In a murine sepsis model, PMB@TimP EVs demonstrated clear in vivo efficacy at an equivalent dose, maintaining survival when free PMB failed. Collectively, this study identified TimP as a conserved target and demonstrated a Trojan-horse drug delivery system capable of restoring the efficacy of PM against MDR gram-negative pathogens.

- Authors (Pusan National University, Department of Chemistry)

 · First author: Hyejin Cho

 · Corresponding author: Kwang-sun Kim

- Title of original paper: The sRNA-encoded peptide TimP rewires the Escherichia coli envelope via LamB to sensitize bacteria to polymyxins

- Journal: Drug Resistance Updates

- Web link: https://www.sciencedirect.com/science/article/pii/S1368764626000579 

- Contact e-mail: kwangsun.kim@pusan.ac.kr