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.