title: Functional Roles of Aromatic Residues and Helices of Papiliocin in its Antimicrobial and Anti-inflammatory Activities.
abstract: A cecropin-like peptide, papiliocin, isolated from the swallowtail butterfly Papilio xuthus, possesses high selectivity against gram-negative bacteria. Since Trp(2) and Phe(5) are highly conserved residues in cecropin-like peptides, we investigated the role of Trp(2) and Phe(5) in antibacterial activity. Substitution of Trp(2) and Phe(5) in papiliocin with Ala (papiliocin-2A and papiliocin-5A) revealed that Trp(2) is a key residue in its antibacterial activities. In order to understand the structural requirements for papiliocin function and to design shorter, but more potent, peptide antibiotics, we designed papiliocin constructs, PapN (residues Arg(1)-Ala(22) from the N-terminal amphipathic helix). PapN exhibited significant broad-spectrum antibacterial activities without cytotoxicity. Bactericidal kinetics of peptides against E.coli showed that papiliocin completely and rapidly killed E.coli in less than 10 minutes at 2× MIC concentration, while papiliocin-2A and papiliocin-5A killed four times more slowly than papiliocin. The PapN series peptides permeabilized bacterial membranes less effectively than papiliocin, showing no antibacterial activities in an hour. The results imply that the Trp(2) and Phe(5) in the amphipathic N-terminal helix are important in the rapid permeabilization of the gram-negative bacterial membrane. The hydrophobic C-terminal residues permeabilize the hydrophobic bacterial cell membrane synergistically with these aromatic residues, providing selectivity against gram-negative bacteria.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Eunjung
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Jin-Kyoung
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Dasom
authors.initials: D
authors.lastname: Jeon
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Ki-Woong
authors.initials: KW
authors.lastname: Jeong
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Areum
authors.initials: A
authors.lastname: Shin
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Yangmee
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000737:chemistry* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D002080:Butterflies / Q000737:chemistry; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006461:Hemolysis; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000096:biosynthesis; D019906:Nuclear Magnetic Resonance, Biomolecular; D016415:Sequence Alignment; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D000893:Anti-Inflammatory Agents; D023181:Antimicrobial Cationic Peptides; D009569:Nitric Oxide