As a human foodborne pathogen, Listeria monocytogenes can cause severe human
listeriosis and develop resistance to
antibiotics.
Antimicrobial peptides (AMPs) are produced from all kingdoms of life and regarded as promising alternatives to conventional
antibiotics.
Jelleine-I is an
AMP identified from honeybees
royal jelly. In this study, we explored the activity and action mechanism of
Jelleine-I against L. monocytogenes. We found its minimum inhibitory concentration to be 12.5 μg/mL. Membrane permeability analysis revealed that
Jelleine-I increased L. monocytogenes cell membrane permeability, causing
calcium leakage. Scanning, transmission electron microscopy and fluorescence microscopy revealed that
Jelleine-I destroyed membrane integrity, disrupted intracellular structures and interacted with the
bacterial DNA.
DNA binding analysis demonstrated that
Jelleine-I bound to bacterial genomic
DNA. Results of reverse transcription-quantitative PCR revealed that
Jelleine-I affected
bacterial DNA replication gene expression levels. Moreover,
Jelleine-I induced cellular
reactive oxygen species (ROS) production from fluorescence intensity analysis, and inhibited bacterial biofilm formation. Results of
immunomodulation in Galleria mellonella revealed that
Jelleine-I increased host hemocyte counts, upregulated host
AMP gene (
Gloverin and
Cecropin D) expression, and inhibited proinfammatory
cytokine (
tumor necrosis factor α and
interleukin 6) production induced by
bacterial infection. It efficiently killed bacteria and increased the survival rate of infected insects to 70 %. Furthermore,
Jelleine-I increased the G1 to S phase transition in mammalian cells from cells cycle analysis, and cytotoxicity assay results indicated that it promoted cell proliferation without
hemolysis or cytotoxicity. Collectively,
Jelleine-I possesses antimicrobial, immunomodulatory and cell proliferative activities, and is a promising candidate for preventing L. monocytogenes emergence and dissemination.