Multi-Lasso\nPeptide-Based Synergistic Nanocomposite:\nA High-Stability, Broad-Spectrum Antimicrobial Agent with Potential\nfor Combined Antibacterial Therapy

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