title: Insight into the antimicrobial activities of coprisin isolated from the dung beetle, Copris tripartitus, revealed by structure-activity relationships.
abstract: The novel 43-residue, insect defensin-like peptide coprisin, isolated from the dung beetle, Copris tripartitus, is a potent antibiotic with bacterial cell selectivity, exhibiting antimicrobial activities against Gram-positive and Gram-negative bacteria without exerting hemolytic activity against human erythrocytes. Tests against Staphylococcus aureus using fluorescent dye leakage and depolarization measurements showed that coprisin targets the bacterial cell membrane. To understand structure-activity relationships, we determined the three-dimensional structure of coprisin in aqueous solution by nuclear magnetic resonance spectroscopy, which showed that coprisin has an amphipathic α-helical structure from Ala(19) to Arg(28), and β-sheets from Gly(31) to Gln(35) and Val(38) to Arg(42). Coprisin has electropositive regions formed by Arg(28), Lys(29), Lys(30), and Arg(42) and ITC results proved that coprisin and LPS have electrostatically driven interactions. Using measurements of nitric oxide release and inflammatory cytokine production, we provide the first verification of the anti-inflammatory activity and associated mechanism of an insect defensin, demonstrating that the anti-inflammatory actions of the defensin-like peptide, coprisin, are initiated by suppressing the binding of LPS to toll-like receptor 4, and subsequently inhibiting the phosphorylation of p38 mitogen-activated protein kinase and nuclear translocation of NF-kB. In conclusion, we have demonstrated that an amphipathic helix and an electropositive surface in coprisin may play important roles in its effective interaction with bacterial cell membranes and, ultimately, in its high antibacterial activity and potent anti-inflammatory activity. In addition to elucidating the antimicrobial action of coprisin, this work may provide insight into the mechanism of action of insect defense systems.
authors.affiliation: Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Institute of SMART Biotechnology, Konkuk University, Seoul 143-701, South Korea.
authors.forename: Eunjung
authors.initials: E
authors.lastname: Lee
authors.forename: Jin-Kyoung
authors.initials: JK
authors.lastname: Kim
authors.forename: Soyoung
authors.initials: S
authors.lastname: Shin
authors.forename: Ki-Woong
authors.initials: KW
authors.lastname: Jeong
authors.forename: Areum
authors.initials: A
authors.lastname: Shin
authors.forename: Juneyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
authors.forename: Jae-Sam
authors.initials: JS
authors.lastname: Hwang
authors.forename: Yangmee
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002460:Cell Line; D001517:Coleoptera; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D007249:Inflammation; D019476:Insect Proteins / Q000737:chemistry*; D015603:Keratinocytes / Q000166:cytology; D008070:Lipopolysaccharides / Q000378:metabolism; D008264:Macrophages / Q000166:cytology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013211:Staphylococcus aureus / Q000378:metabolism; D013329:Structure-Activity Relationship; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D016207:Cytokines; D019476:Insect Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010455:Peptides; D051197:Toll-Like Receptor 4; C570442:coprisin peptide, Copris tripartitus; D009569:Nitric Oxide; D048051:p38 Mitogen-Activated Protein Kinases