End-tagging of ultra-short antimicrobial peptides by W/F stretches to facilitate bacterial killing

• Published in: PloS one Vol. 4; no. 4; p. e5285
• Main Authors: Pasupuleti, Mukesh, Schmidtchen, Artur, Chalupka, Anna, Ringstad, Lovisa, Malmsten, Martin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 17.04.2009; Public Library of Science (PLoS)
• Subjects: Adsorption; Amino Acid Sequence; Amino acids; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacokinetics; Anti-Bacterial Agents - pharmacology; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial peptides; Aureolysin; Bacteria; Binding; Bioavailability; Biochemistry; Biochemistry/Drug Discovery; Biodegradation; Biological Availability; Biotechnology/Applied Microbiology; Biotechnology/Protein Chemistry and Proteomics; Cell Line; Cholesterol; Clinical Medicine; Dermatologi och venereologi; Dermatology; Dermatology and Venereal Diseases; Drug resistance in microorganisms; E coli; Elastase; Escherichia coli; Escherichia coli - drug effects; Experiments; FARMACI; Fatty acids; Health aspects; Humans; Hydrophobicity; Immunology/Innate Immunity; Ionic strength; Kininogens; Klinisk medicin; Leukocyte elastase; Lipopolysaccharides; Liposomes; Marking; Medical and Health Sciences; MEDICIN; Medicin och hälsovetenskap; MEDICINE; Membranes; Microbial Sensitivity Tests; Microbiology/Innate Immunity; Microorganisms; Mitogens; Molecular Sequence Data; Pattern recognition; Peptide synthesis; Peptides; Peptides - chemistry; Peptides - pharmacokinetics; Peptides - pharmacology; PHARMACY; Physiology; Propionibacterium; Proteinase; Proteolysis; Rupture; Rupturing; Salts; Selectivity; Skin; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus infections; Studies; Surface active agents; Synthesis; Toxicity; United States > US; Sweden
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0005285

Due to increasing resistance development among bacteria, antimicrobial peptides (AMPs), are receiving increased attention. Ideally, AMP should display high bactericidal potency, but low toxicity against (human) eukaryotic cells. Additionally, short and proteolytically stable AMPs are desired to maximize bioavailability and therapeutic versatility. A facile approach is demonstrated for reaching high potency of ultra-short antimicrobal peptides through end-tagging with W and F stretches. Focusing on a peptide derived from kininogen, KNKGKKNGKH (KNK10) and truncations thereof, end-tagging resulted in enhanced bactericidal effect against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Through end-tagging, potency and salt resistance could be maintained down to 4-7 amino acids in the hydrophilic template peptide. Although tagging resulted in increased eukaryotic cell permeabilization at low ionic strength, the latter was insignificant at physiological ionic strength and in the presence of serum. Quantitatively, the most potent peptides investigated displayed bactericidal effects comparable to, or in excess of, that of the benchmark antimicrobial peptide LL-37. The higher bactericidal potency of the tagged peptides correlated to a higher degree of binding to bacteria, and resulting bacterial wall rupture. Analogously, tagging enhanced peptide-induced rupture of liposomes, particularly anionic ones. Additionally, end-tagging facilitated binding to bacterial lipopolysaccharide, both effects probably contributing to the selectivity displayed by these peptides between bacteria and eukaryotic cells. Importantly, W-tagging resulted in peptides with maintained stability against proteolytic degradation by human leukocyte elastase, as well as staphylococcal aureolysin and V8 proteinase. The biological relevance of these findings was demonstrated ex vivo for pig skin infected by S. aureus and E. coli. End-tagging by hydrophobic amino acid stretches may be employed to enhance bactericidal potency also of ultra-short AMPs at maintained limited toxicity. The approach is of general applicability, and facilitates straightforward synthesis of hydrophobically modified AMPs without the need for post-peptide synthesis modifications.