Temperature-dependent activity of pediocin PA-1 and a Cys-Ser mutant: a dual in silico-in vitro analysis

Aim: This study aimed to investigate how the presence or absence of disulfide bonds affects the antimicrobial activity and thermal stability of pediocin PA-1. Methods: To achieve this, the native pediocin peptide and a Cys → Ser mutant lacking the disulfide bridge were evaluated using both in vitro assays and molecular dynamics simulations. Antimicrobial activities of pediocin PA-1 and the mutant peptide were tested at varying temperatures (25–100°C) against selected indicator microorganisms. In parallel, molecular dynamics simulations were performed for both peptides, and RMSD, RMSF, and DSSP analyses were conducted to evaluate structural stability and secondary structure profiles. Results: The Cys → Ser mutant peptide exhibited a substantial loss of antimicrobial activity, especially at elevated temperatures, demonstrating the necessity of the disulfide bridge for functional stability. In contrast, pediocin PA-1 retained approximately 96% of its activity even after exposure to 100°C. In silico analyses revealed that while the mutant partially preserved α-helix and β-sheet elements, it displayed pronounced disruption in its three-dimensional conformation. Conclusions: The results highlight the critical structural role of Cys residues and disulfide bonds in ensuring both antimicrobial functionality and thermal resilience of pediocin PA-1. These findings provide valuable insights for the rational design of thermally stable antimicrobial peptides for food industry applications.