Tryptophan end-tagging of antimicrobial peptides for increased potency against Pseudomonas aeruginosa.
BACKGROUND
Due to increasing antibiotics resistance, antimicrobial peptides (AMPs) are receiving increased attention. Pseudomonas aeruginosa is a major pathogen in this context, involved, e.g., in keratitis and wound infections. Novel bactericidal agents against this pathogen are therefore needed.


METHODS
Bactericidal potency was monitored by radial diffusion, viable count, and minimal inhibitory concentration assays, while toxicity was probed by hemolysis. Mechanistic information was obtained from assays on peptide-induced vesicle disruption and lipopolysaccharide binding.


RESULTS
End-tagging by hydrophobic amino acids yields increased potency of AMPs against P. aeruginosa, irrespective of bacterial proteinase production. Exemplifying this by two peptides from kininogen, GKHKNKGKKNGKHNGWK and KNKGKKNGKH, potency increased with tag length, correlating to more efficient bacterial wall and vesicle rupture, and to more pronounced P. aeruginosa lipopolysaccharide binding. End-tag effects remained at high electrolyte concentration and in the presence of plasma or anionic macromolecular scavengers. The tagged peptides displayed stability against P. aeruginosa elastase, and were potent ex vivo, both in a contact lens model and in a skin wound model.


CONCLUSIONS
End-tagging, without need for post-peptide synthesis modification, may be employed to enhance AMP potency against P. aeruginosa at maintained limited toxicity.
Section of Dermatology and Venereology, Department of Clinical Sciences, Lund University, SE-22184 Lund, Sweden.
Mukesh
M
Pasupuleti
Anna
A
Chalupka
Matthias
M
Mörgelin
Artur
A
Schmidtchen
Martin
M
Malmsten
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D008051:Lipid Bilayers / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D008969:Molecular Sequence Data; D010539:Permeability / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D034421:Sus scrofa; D014364:Tryptophan / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D008070:Lipopolysaccharides; D014364:Tryptophan