Antimicrobial activity of lysozyme isoforms: Key molecular features

Area of Science:

• Microbiology
• Biochemistry
• Protein Science

Background:

• Rising antibiotic resistance necessitates novel antimicrobial strategies.
• Proteins targeting bacterial membranes offer a promising alternative.
• Lysozyme demonstrates antibacterial activity against E. coli, enhanced by dry-heating.

Purpose of the Study:

• To investigate the individual effects and critical physicochemical properties of dry-heated lysozyme (DH-L) isoforms on bacterial membranes.
• To determine which properties confer antibacterial activity.
• To explore potential synergistic interactions between DH-L isoforms.

Main Methods:

• Fractionation of dry-heated lysozyme (DH-L) into its constituent isoforms.
• Analysis of structural and physicochemical properties of each fraction.
• In vivo testing of fractions against E. coli and in vitro testing on model membranes.

Main Results:

• Positive net charge, hydrophobicity, and molecular flexibility were identified as key parameters for membrane interaction.
• Succinimide lysozyme, exhibiting the highest positive charge, flexibility, and hydrophobicity, demonstrated the greatest antimicrobial activity and membrane disruption.
• Individual DH-L fractions were less effective than the combined DH-L mixture, suggesting isoform synergy.

Conclusions:

• Physicochemical properties like charge, hydrophobicity, and flexibility are critical for lysozyme's antibacterial action against E. coli.
• Succinimide lysozyme is the most potent isoform, driving significant membrane disruption.
• Synergistic cooperation between lysozyme isoforms enhances overall antimicrobial efficacy, with modifications by one isoform potentially facilitating others.