Rational Redesign of an α-Helical Marine Toxin Scaffold Enables a Safe and Broad-Spectrum Anti-ESKAPE Lipopeptide

The surge in multidrug-resistant (MDR) pathogens necessitates novel therapeutic strategies. Here, we report the rational design of C4-VG7, an N-terminal butyrylated lipopeptide engineered from a compact, cationic, helix-compatible segment of the marine conotoxin αO-GeXIVA. Through stepwise structural optimization─from constrained cyclic prototypes to lipidated derivatives─C4-VG7 was identified as a lead candidate with potent, broad-spectrum activity against MDR ESKAPE pathogens, including clinical isolates (MIC ≈1 μM). Mechanistically, C4-VG7 exhibits multimodal bactericidal action: C4-tail-mediated membrane depolarization is consistent with early membrane disruption followed by intracellular DNA association and oxidative stress. In murine models of MRSA and Acinetobacter baumannii infections (skin and peritonitis), C4-VG7 achieved efficacy comparable to polymyxin B with significantly reduced hepatonephrotoxicity. Thus, C4-VG7 represents a systemically viable, well-tolerated candidate for combating MDR ESKAPE infections.