title: Structure-activity relationships of the intramolecular disulfide bonds in coprisin, a defensin from the dung beetle.
abstract: Defensins, which are small cationic molecules produced by organisms as part of their innate immune response, share a common structural scaffold that is stabilized by three disulfide bridges. Coprisin is a 43-amino acid defensin-like peptide from Copris tripartitus. Here, we report the intramolecular disulfide connectivity of cysteine-rich coprisin, and show that it is the same as in other insect defensins. The disulfide bond pairings of coprisin were determined by combining the enzymatic cleavage and mass analysis. We found that the loss of any single disulfide bond in coprisin eliminated all antibacterial, but not antifungal, activity. Circular dichroism (CD) analysis showed that two disulfide bonds, Cys20-Cys39 and Cys24-Cys41, stabilize coprisin's α-helical region. Moreover, a BLAST search against UniProtKB database revealed that coprisin's α-helical region is highly homologous to those of other insect defensins.
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Jaeho
authors.initials: J
authors.lastname: Lee
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Daeun
authors.initials: D
authors.lastname: Lee
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea.
authors.forename: Hyemin
authors.initials: H
authors.lastname: Choi
authors.affiliation: College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea.
authors.forename: Ha Hyung
authors.initials: HH
authors.lastname: Kim
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Science, Daejin University, Pocheon 487-711, Korea.
authors.forename: Ho
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Agricultural Biology, Natural Academy of Agricultural Science, RDA, Suwon 441-707, Korea.
authors.forename: Jae Sam
authors.initials: JS
authors.lastname: Hwang
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea.
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
authors.affiliation: School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Jae Il
authors.initials: JI
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D020134:Catalytic Domain; D002942:Circular Dichroism; D001517:Coleoptera; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D005658:Fungi / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D019476:Insect Proteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D004220:Disulfides; D019476:Insect Proteins; C570442:coprisin peptide, Copris tripartitus; D003545:Cysteine