Antimicrobial Peptides with High Proteolytic Resistance for Combating Gram-Negative Bacteria

Area of Science:

• Biochemistry
• Microbiology
• Peptide Science

Background:

• Antimicrobial peptides (AMPs) face challenges in clinical use due to poor resistance to proteases.
• Existing solutions for protease resistance, like chemical modifications or d-amino acids, increase production costs and complexity.
• A need exists for cost-effective and robust AMPs targeting Gram-negative bacteria.

Purpose of the Study:

• To design and synthesize novel peptides with inherent proteolytic resistance.
• To evaluate the efficacy and mechanism of action of these peptides against Gram-negative bacteria.
• To develop a new strategy for creating antiprotease hydrolytic peptides for clinical applications.

Main Methods:

• Systematic design of peptides based on an antitrypsin/antichymotrypsin hydrolytic peptide structure unit (XYPX)n using natural amino acids.
• Synthesis and characterization of a set of novel peptides.
• In vitro evaluation of proteolytic resistance, antibacterial activity, and selectivity index against Gram-negative bacteria.
• In vivo assessment of efficacy against Escherichia coli infection.

Main Results:

• Peptide 16, with seven repeat units, demonstrated the highest average selectivity index (GM_SI = 99.07) against tested Gram-negative bacteria.
• Peptide 16 exhibited significant resistance to high concentrations of trypsin/chymotrypsin hydrolysis.
• Peptide 16 effectively combated Escherichia coli infection in vivo and acted via a membrane-disruptive mechanism.

Conclusions:

• The novel peptide design strategy yields AMPs with substantial antiprotease activity.
• Peptide 16 represents a promising candidate for developing therapeutics against Gram-negative bacterial infections.
• This work offers a new avenue for creating robust, cost-effective antimicrobial peptides.