Antibacterial Activity and Mechanisms of TroHepc2-22, a Derived Peptide of Hepcidin2 from Golden Pompano (Trachinotus ovatus)

Abstract

Hepcidin, a cysteine-rich antimicrobial peptide, has a highly conserved gene structure in teleosts, and it plays an essential role in host immune response against various pathogenic bacteria. Nonetheless, few studies on the antibacterial mechanism of hepcidin in golden pompano (Trachinotus ovatus) have been reported. In this study, we synthesized a derived peptide, TroHepc2-22, from the mature peptide of T. ovatus hepcidin2. Our results showed that TroHepc2-22 has superior antibacterial abilities against both Gram-negative (Vibrio harveyi and Edwardsiella piscicida) and Gram-positive (Staphylococcus aureus and Streptococcus agalactiae) bacteria. Based on the results of a bacterial membrane depolarization assay and propidium iodide (PI) staining assay in vitro, TroHepc2-22 displayed antimicrobial activity by inducing the bacterial membrane depolarization and changing the bacterial membrane permeability. Scanning electron microscopy (SEM) visualization illustrated that TroHepc2-22 brought about membrane rupturing and the leakage of the cytoplasm for the bacteria. In addition, TroHepc2-22 was verified to have hydrolytic activity on bacterial genomic DNA in view of the results of the gel retardation assay. In terms of the in vivo assay, the bacterial loads of V. harveyi in the tested immune tissues (liver, spleen, and head kidney) were significantly reduced in T. ovatus, revealing that TroHepc2-22 significantly enhanced the resistance against V. harveyi infection. Furthermore, the expressions of immune-related genes, including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin 1-β (IL-1β), IL-6, Toll-like receptor 1 (TLR1), and myeloid differentiation factor 88 (MyD88) were significantly increased, indicating that TroHepc2-22 might regulate inflammatory cytokines and activate immune-related signaling pathways. To summarize, TroHepc2-22 possesses appreciable antimicrobial activity and plays a vital role in resisting bacterial infection. The observation of our present study unveils the excellent application prospect of hepcidin as a substitute for antibiotics to resist pathogenic microorganisms in teleosts.

Genomic and metabolomic profiling reveal Streptomyces rochei S32 contributes to plant growth by nitrogen fixation and production of bioactive substances

“…Lipopeptide and borrelidin are both antimicrobial peptides synthesized by nonribosomal peptide synthetase. Lipopeptide is a biosurfactant that exerts a broad-spectrum antimicrobial effect by disrupting the integrity of cell outer and inner membranes (Dasgupta et al 2023;Zhang et al 2023). Borrelidin, an inhibitor of threonine transfer RNA synthase (Li et al 2014), inhibits protein synthesis in bacteria, fungi, and viruses (Shirokikh et al 2023).…”

Genome-Wide Identification of Trachinotus ovatus Antimicrobial Peptides and Their Immune Response against Two Pathogen Challenges

“…This peptide demonstrated excellent antimicrobial capabilities against both Gram-negative (Vibrio harveyi and Edwardsiella piscicida) and Gram-positive (Staphylococcus aureus and S. agalactiae) bacteria. It is presumed that the antimicrobial activity of TroHepc2-22 was exerted by disrupting the bacterial membrane structure and subsequently hydrolyzing bacterial gDNA [58]. Another widely studied AMP, LEAP-2, a member of the hepcidin family, has also been found to be highly expressed in the spleen and kidney following infection with S. agalactiae.…”