Multi-Lasso Peptide-Based Synergistic Nanocomposite: A High-Stability, Broad-Spectrum Antimicrobial Agent with Potential for Combined Antibacterial Therapy

Lasso peptides, natural biological microcins composed of small molecules, have demonstrated efficient bactericidal activity. However, a single lasso peptide is characterized by a narrow and targeted bactericidal spectrum. In this study, a chitosan (CN) derivative-based polymer nanomaterial incorporating three lasso peptides (MccY, MccJ25, and Klebsidin) was designed and synthesized to broaden its antimicrobial spectrum. To enhance resistance to acid and alkali conditions, arginine was appended to the terminus of conjugates, resulting in Chitosan-Lasso-Peptides-Arg (CN-LPs-Arg), and the nanomaterial biocompatibility and bactericidal activity were characterized. Chemical stability test results demonstrate that CN-LPs-Arg effectively buffered the acid-base effect of the compound. Notably, CN-LPs-Arg extended the antimicrobial spectrum of Gram-negative and Gram-positive strains including Klebsiella, Salmonella, and Staphylococcus (MIC = 0.01-1.0 μM). CN-LPs-Arg exerts its destructive effects on bacteria via a series of mechanisms; it adheres to and then penetrates the membrane, causes rupture, and leads to bacterial death. Transcriptomic data revealed that CN-LPs-Arg produced a distinct inhibitory effect on ribosomal protein subunits synthesis pathways and membrane metabolic inhibition. Furthermore, CN-LPs-Arg was nontoxic to cells and exhibited excellent biocompatibility. CN-LPs-Arg reduced bacterial burden in organs and the levels of inflammatory factors IL-6, IL-8, and TNF-α in tissues of mice with acute bacterial infections. Furthermore, it promoted the recovery of Klebsiella-infected C57BL/6 mice, demonstrating a favorable therapeutic effect in vivo. The multilasso peptide-based synergistic nanocomposite of CN-LPs-Arg exhibited high stability as a broad-spectrum antimicrobial agent with potential for combined antibacterial therapy and utilization in the fields of food, biomedicine, and public health.