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Published on: May 4, 2018
Milk-derived antimicrobial peptide GMp7: Disrupting protein networks for multi-target antibacterial inhibition and
Jinze He1, Hong Li2, Yujuan Xu3
1Sericultural and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Product Processing, Guangzhou, 510610, China; College of Food Science and Technology, Yunnan Agricultural University, Kunming, 650201, Yunnan, China.
Abstract:
Our goal was to identify and characterize a novel milk-derived antimicrobial peptide, GMp7, and reveal its antibacterial mechanism against Staphylococcus aureus. 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, 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. Treatment with GMp7 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, ATP-binding cassette transport, the 2-component system, DNA replication, and mismatch repair. The efficacy of the peptide against S. aureus in pasteurized 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.
Insights
A novel milk peptide, GMp7, effectively combats Staphylococcus aureus by disrupting bacterial cell membranes and interfering with essential proteins. This peptide shows promise for enhancing food safety and extending the shelf life of dairy products.
Area of Science:
- Microbiology
- Biochemistry
- Food Science
Background:
- Antimicrobial peptides (AMPs) are crucial for innate immunity and represent a promising alternative to conventional antibiotics.
- Staphylococcus aureus is a significant pathogen in food products, necessitating effective control strategies.
- Identifying novel AMPs with potent antibacterial activity against S. aureus is of high importance for food safety.
Purpose of the Study:
- To identify and characterize a novel milk-derived antimicrobial peptide, GMp7.
- To elucidate the multi-target antibacterial mechanism of GMp7 against Staphylococcus aureus.
- To evaluate the efficacy of GMp7 in inhibiting S. aureus growth in pasteurized milk.
Main Methods:
- Fourier-transform infrared spectroscopy, flow cytometry, and scanning electron microscopy were used to analyze GMp7's effects on bacterial cells.
- Label-free proteomics analysis identified protein targets and quantified proteome changes induced by GMp7.
- Molecular docking was employed to predict binding affinities of GMp7 to key S. aureus proteins.
Main Results:
- GMp7 possesses a secondary structure (17.45% α-helix, 20.10% β-corner, 37.13% β-fold) conducive to membrane disruption.
- Proteomic analysis revealed GMp7 downregulates 99 proteins and upregulates 26, indicating a multi-target mechanism.
- GMp7 binds strongly to essential S. aureus proteins asd and pcrA, with binding energies of -8.477 and -8.407 kcal/mol, respectively.
- GMp7 interferes with peptidoglycan biosynthesis, ABC transport, 2-component systems, DNA replication, and mismatch repair.
- GMp7 significantly inhibited S. aureus growth in pasteurized milk.
Conclusions:
- GMp7 exhibits a potent, multi-target antibacterial mechanism against Staphylococcus aureus.
- The peptide's ability to disrupt bacterial membranes and inhibit essential cellular processes contributes to its efficacy.
- GMp7 demonstrates significant potential for application in the dairy industry to improve food safety and extend product shelf life.
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