title: Rational design of tryptophan-rich antimicrobial peptides with enhanced antimicrobial activities and specificities.
abstract: Trp-rich antimicrobial peptides play important roles in the host innate defense mechanism of many plants and animals. A series of short Trp-rich peptides derived from the C-terminal region of Bothrops asper myothoxin II, a Lys49 phospholipase A(2) (PLA(2)), were found to reproduce the antimicrobial activities of their parent molecule. Of these peptides, KKWRWWLKALAKK-designated PEM-2-was found to display improved activity against both Gram-positive and Gram-negative bacteria. To improve the antimicrobial activity of PEM-2 for potential clinical applications further, we determined the solution structure of PEM-2 bound to membrane-mimetic dodecylphosphocholine (DPC) micelles by two-dimensional NMR methods. The DPC micelle-bound structure of PEM-2 adopts an α-helical conformation and the positively charged residues are clustered together to form a hydrophilic patch. The surface electrostatic potential map indicates that two of the three tryptophan residues are packed against the peptide backbone and form a hydrophobic face with Leu7, Ala9, and Leu10. A variety of biophysical and biochemical experiments, including circular dichroism, fluorescence spectroscopy, and microcalorimetry, were used to show that PEM-2 interacted with negatively charged phospholipid vesicles and efficiently induced dye release from these vesicles, suggesting that the antimicrobial activity of PEM-2 could be due to interactions with bacterial membranes. Potent analogues of PEM-2 with enhanced antimicrobial and less pronounced hemolytic activities were designed with the aid of these structural studies.
authors.affiliation: Institute of Biotechnology, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Hui-Yuan
authors.initials: HY
authors.lastname: Yu
authors.forename: Kuo-Chun
authors.initials: KC
authors.lastname: Huang
authors.forename: Bak-Sau
authors.initials: BS
authors.lastname: Yip
authors.forename: Chih-Hsiang
authors.initials: CH
authors.lastname: Tu
authors.forename: Heng-Li
authors.initials: HL
authors.lastname: Chen
authors.forename: Hsi-Tsung
authors.initials: HT
authors.lastname: Cheng
authors.forename: Jya-Wei
authors.initials: JW
authors.lastname: Cheng
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology; D002151:Calorimetry; D002942:Circular Dichroism; D015195:Drug Design; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008826:Microbial Sensitivity Tests; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008823:Micelles; D010767:Phosphorylcholine; C028810:dodecylphosphocholine; D014364:Tryptophan