Proline-Rich Peptides with Improved Antimicrobial Activity against E. coli, K. pneumoniae, and A. baumannii

Area of Science:

• Microbiology
• Peptide Chemistry
• Drug Discovery

Background:

• Proline-rich antimicrobial peptides (PrAMPs) offer a promising strategy against multi-drug resistant pathogens due to their potent antimicrobial effects and low cytotoxicity.
• Bac5(1-17), a known PrAMP, serves as a scaffold for developing novel antimicrobial agents.

Purpose of the Study:

• To synthesize and screen Bac5(1-17) derivatives to identify key residues for antimicrobial activity.
• To develop novel PrAMPs with improved efficacy, broader spectrum, and dual mechanisms of action to combat antimicrobial resistance.

Main Methods:

• Synthesis of a library of Bac5(1-17) derivatives with variations at N- and C-termini.
• Antimicrobial activity screening against various pathogens.
• Cytotoxicity assays on eukaryotic cells.
• Transcription/translation inhibition assays.
• Bacterial membrane permeabilization assays.

Main Results:

• Identified essential central motifs (-PIRXP-) within Bac5(1-17) that are intolerant to modification.
• Discovered five derivatives with 1-5 substitutions, particularly increased arginine and tryptophan residues, demonstrating enhanced antimicrobial activity and spectrum.
• Confirmed retained inhibition of bacterial protein synthesis and acquired varying degrees of bacterial membrane permeabilization.
• Maintained low cytotoxicity toward eukaryotic cells.

Conclusions:

• Novel Bac5(1-17) derivatives with enhanced antimicrobial properties and a dual mode of action (protein synthesis inhibition and membrane permeabilization) were developed.
• These derivatives show potential for combating multi-drug resistant pathogens by hindering resistance development.
• The findings highlight the therapeutic potential of modified PrAMPs in addressing the global challenge of antimicrobial resistance.