Resurrecting inactive antimicrobial peptides from the lipopolysaccharide trap

Area of Science:

• Microbiology
• Biochemistry
• Drug Discovery

Background:

• Host defense antimicrobial peptides (AMPs) show promise against drug-resistant bacteria.
• Lipopolysaccharide (LPS) in Gram-negative bacteria forms a barrier, inactivating AMPs by causing aggregation.
• LPS (endotoxin) is a major cause of sepsis-related mortality.

Purpose of the Study:

• To develop a strategy to overcome LPS-induced inactivation of AMPs.
• To create novel hybrid peptides with enhanced antimicrobial activity.
• To investigate the mechanism of action of these new peptides.

Main Methods:

• Conjugation of AMPs with an LPS-binding β-boomerang peptide motif.
• Testing hybrid peptide activity against Gram-negative and Gram-positive bacteria.
• Structural and biophysical studies to elucidate the mechanism of action.

Main Results:

• Hybrid peptides overcome LPS-induced aggregation, regaining bactericidal activity.
• The novel peptides are effective against both Gram-negative and Gram-positive bacteria, even in high salt conditions.
• The peptides demonstrate endotoxin-detoxifying properties and disrupt the bacterial outer membrane.

Conclusions:

• Conjugating AMPs with LPS-binding motifs is a viable strategy to create potent broad-spectrum antibiotics.
• This approach overcomes a key limitation of AMPs against Gram-negative bacteria.
• The developed hybrid peptides offer a new therapeutic concept for treating bacterial infections and sepsis.