Insight into the antimicrobial activities of coprisin isolated from the dung beetle, Copris tripartitus, revealed by structure-activity relationships

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• 作者：Eunjung Lee^a ; Jin-Kyoung Kim^a ; Soyoung Shin^a ; Ki-Woong Jeong^a ; Areum Shin^a ; Juneyoung Lee^b ; Dong Gun Lee^b ; Jae-Sam Hwang^c ; Yangmee Kim^a ; ^{ymkim@konkuk.ac.kr}
• 关键词：AMP ; antimicrobial peptide ; BSA ; bovine serum albumin ; CCARM ; Culture Collection of Antibiotic-Resistant Microbe ; CCS ; combined consensus scale ; CD ; circular dichroism ; CH ; cholesterol ; CSI ; chemical shift index ; diSC3-5 ; 3 ; 3&prime ; -dipropylthiadicarbo-cy
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2013
• 出版时间：February, 2013
• 年：2013
• 卷：1828
• 期：2
• 页码：271-283
• 全文大小：1355 K

文摘

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 ¦Á-helical structure from Ala¹⁹ to Arg²⁸, and ¦Â-sheets from Gly³¹ to Gln³⁵ and Val³⁸ to Arg⁴². Coprisin has electropositive regions formed by Arg²⁸, Lys²⁹, Lys³⁰, and Arg⁴² 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.