Self-assembling D4W peptide nanofibrils eradicate drug-resistant Staphylococci and inhibit biofilm formation

Antibiotic resistance, particularly from methicillin-resistant Staphylococcus aureus (MRSA), poses a severe global health challenge, leading to persistent and difficult-to-treat infections. A major factor contributing to this resistance is the formation of bacterial biofilms, which shield bacteria from antibiotics and host immune responses. Current standard-of-care antibiotics often struggle to penetrate and eradicate these biofilms, necessitating novel therapeutic strategies. Peptides, with their diverse mechanisms of action like membrane disruption and high specificity, offer a promising avenue for developing new antibacterial agents that can overcome these limitations.

Researchers developed self-assembling, tryptophan-rich peptide nanofibrils, designated D4W (derived from DVFLGREEWWWWC), and evaluated their antibacterial efficacy. These D4W units form stable amyloid fibril-like structures via controlled polarity reversal. Their activity was assessed against various Staphylococcus species, including MRSA, in both planktonic cultures and for their ability to inhibit biofilm formation. The mechanism of action, specifically membrane penetration and disruption, was investigated. Efficacy was further validated in ex vivo pig skin and in vivo zebrafish embryo models. Additionally, cytotoxicity and hemotoxicity were evaluated to assess therapeutic potential, and molecular dynamics simulations elucidated interactions with lipid membranes.

The self-assembling D4W peptide nanofibrils demonstrated potent antibacterial activity against various Staphylococcus species, including methicillin-resistant Staphylococcus aureus (MRSA). The unique DVFLG motif within D4W enabled selective recognition of Staphylococci, while the WWWW segment facilitated β-sheet formation and deep membrane penetration via hydrophobic interactions, leading to effective disruption of bacterial membranes. This targeted approach enhanced antibacterial efficacy. > D4W-derived nanofibrils engaged in multivalent interactions with bacterial surfaces, significantly enhancing targeting precision and antibacterial efficacy against planktonic Staphylococci. Beyond eradicating free-floating bacteria, these nanofibrils also significantly inhibited biofilm formation, a critical factor in antibiotic resistance and persistent infections. Importantly, the D4W-derived nanofibrils exhibited low cytotoxicity and hemotoxicity, suggesting a favorable safety profile for potential therapeutic applications. Their efficacy was further validated in complex biological models: they successfully inhibited MRSA growth in ex vivo pig skin and in vivo zebrafish embryo models. Molecular dynamics simulations provided insights into the precise interactions between D4W and model lipid membranes, confirming the proposed membrane disruption mechanism.