title: Importance of Tryptophan in Transforming an Amphipathic Peptide into a Pseudomonas aeruginosa-Targeted Antimicrobial Peptide.
abstract: Here, we found that simple substitution of amino acids in the middle position of the hydrophobic face of an amphipathic peptide RI16 with tryptophan (T9W) considerably transformed into an antimicrobial peptide specifically targeting Pseudomonas aeruginosa. Minimal inhibitory concentration (MIC) results demonstrated that T9W had a strong and specifically antimicrobial activity against P. aeruginosa, including antibiotic-resistant strains, but was not active against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Staphyfococcus epidermidis. Fluorescent spectroscopic assays indicated that T9W interacted with the membrane of P. aeruginosa, depolarizing the outer and the inner membrane of bacterial cells. Salt susceptibility assay showed that T9W still maintained its strong anti-pseudomonas activity in the presence of salts at physiological concentrations, and in hemolytic and MTT assays T9W also showed no toxicity against human blood cells and macrophages. In vivo assay demonstrated that T9W also displayed no toxicity to Chinese Kun Ming (KM) mice. Furthermore, the strong antibiofilm activity was also observed with the peptide T9W, which decreased the percentage of biomass formation in a dose-dependent manner. Overall, these findings indicated that design of single-pathogen antimicrobial agents can be achieved by simple amino acid mutation in naturally occurring peptide sequences and this study suggested a model of optimization/design of anti-pseudomonas drugs in which the tryptophan residue was a conserved element.
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Chou
authors.affiliation: Institute of Animal Nutrition, Northeast Agricultural University, Harbin, China.
authors.forename: Anshan
authors.initials: A
authors.lastname: Shan
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008826:Microbial Sensitivity Tests; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D014364:Tryptophan