Milk-derived antimicrobial peptide GMp7: Disrupting protein networks for multi-target antibacterial inhibition and enhanced dairy preservation.

Abstract

Identification and characterization of a novel milk-derived antimicrobial peptide, GMp7 (KVLPVPQ), with potent antibacterial activity against Staphylococcus aureus and a demonstrated safety profile. Therefore, this study revealed the multi-target antibacterial mechanism of GMp7 on S. aureus DC.RB-015 by Fourier transform infrared spectroscopy, flow cytometry, scanning electron microscopy (SEM) and label-free proteomics analysis. The results showed that GMp7 has a secondary structure consisting of 17.45% α-helix, 20.10% β-corner and 37.13% β-fold, which is conducive to membrane disruption and bacterial cell death. GMp7 treatment induced a significant change in the proteome, resulting in the downregulation of 99 proteins and the upregulation of 26 proteins, indicating a multi-target effect on bacterial physiology. Notably, GMp7 forms stable bonds with the critical proteins asd and pcrA within the S. aureus protein network, which includes a larger network of 17 proteins essential for bacterial viability. The binding energies for GMp7 with asd and pcrA were determined to be -8.477 and -8.407 kcal/mol, respectively. GMp7 exerts its bacteriostatic effects through multiple pathways, including interference with peptidoglycan biosynthesis, ABC transport, the 2-component system, DNA replication and mismatch repair. The efficacy of the peptide against S. aureus in pasteurised milk suggests its potential use in the dairy industry to improve product shelf life and safety. In addition, GMp7 significantly inhibited the growth of S. aureus in milk. These findings have practical significance for the use of antimicrobial peptides to control bacterial contamination in food and improve food safety.