Antibacterial Peptide NP-6 Affects Staphylococcus aureus by Multiple Modes of Action

Our previous study extracted and identified an antibacterial peptide that was named NP-6. Herein, we investigated the physicochemical properties of NP-6, and elucidated the mechanisms underlying its antimicrobial activity against Staphylococcus aureus. The results showed that the hemolysis activity of NP-6 was 2.39 +/- 0.13%, lower than Nisin A (3.91 +/- 0.43%) at the same concentration (512 mu g/mL). Negligible cytotoxicity towards RAW264.7 cells was found when the concentration of NP-6 was lower than 512 mu g/mL. In addition, it could keep most of its activity in fetal bovine serum. Moreover, transmission electron microscopy, confocal laser scanning microscopy, and flow cytometry results showed that NP-6 can destroy the integrity of the bacterial cell membrane and increase the membrane permeability. Meanwhile, NP-6 had binding activity with bacterial DNA and RNA in vitro and strongly inhibited the intracellular beta-galactosidase activity of S. aureus. Our findings suggest that NP-6 could be a promising candidate against S. aureus.

Automated summary

Our study investigated the physicochemical properties of antibacterial peptide NP-6 and elucidated its antimicrobial mechanisms against Staphylococcus aureus. The results showed that NP-6 can disrupt the bacterial cell membrane and inhibit the activity of intracellular enzymes. These findings suggest that NP-6 has the potential to be a promising candidate for combating Staphylococcus aureus.