Selective Serine Substitutions of Antimicrobial Peptides Reveal Different Mechanistic Actions Toward Gram-Negative...

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Antimicrobial resistance (AMR) is a growing global health threat, driven by antibiotic overuse.
• Gram-negative bacteria (e.g., E. coli, P. aeruginosa) are major contributors to AMR-related mortality.
• Alternative treatments to conventional antibiotics are urgently needed.

Purpose of the Study:

• To investigate the impact of substituting Lysine with Serine in a designed antimicrobial peptide (AMP), G(IIKK)3I-NH2.
• To understand how these sequence modifications affect AMPs' membrane disruption capabilities against Gram-negative bacteria.
• To explore the potential of Serine-containing AMPs as novel therapeutics against AMR.

Main Methods:

• Antimicrobial assays to evaluate peptide efficacy.
• Neutron reflection to study peptide-membrane interactions.
• Molecular dynamics (MD) simulations to analyze structural changes and aggregation.
• Investigated Gram-negative bacterial membrane disruption.

Main Results:

• Selective Serine substitutions altered the AMP's action and membrane disruption.
• Serine-rich AMPs demonstrated improved antimicrobial activity.
• Intramembrane aggregations were linked to enhanced antimicrobial effects.
• Demonstrated differential disruption of inner and outer bacterial membranes.

Conclusions:

• Serine-containing AMPs exhibit significant potential for developing new treatments against AMR infections.
• Modulating AMP sequence through amino acid substitution offers a rational design approach.
• These findings support AMPs as a viable alternative to traditional antibiotics.