title: Determination of the antibacterial and lipopolysaccharide-neutralizing regions of guinea pig neutrophil cathelicidin peptide CAP11.
abstract: Previously, we revealed that a cationic antibacterial polypeptide of 11 kDa (CAP11), a member of the cathelicidins isolated from guinea pig neutrophils, exhibits not only potent antibacterial activity but also lipopolysaccharide (LPS)-neutralizing activity. In this study, to determine the biologically active regions of CAP11, we isolated or synthesized the partial peptides of CAP11 and evaluated their antibacterial and LPS-neutralizing activities. Although CAP11 has a unique homodimeric structure with a disulfide bridge, the biological activities of dimeric and monomeric forms of CAP11 were almost the same. Moreover, the G(1)-E(33) peptide of CAP11 showed the same activities as CAP11, whereas the C-terminal region (Y(34) to I(43)) possessed no biological activities. In addition, the three 18-mer peptides (G(1)-R(18), T(9)-K(26), and L(16)-E(33)) with overlapping sequences were synthesized, and their activities were determined. The three 18-mer peptides retained the antibacterial activities, and G(1)-R(18) was the most potent. In contrast, the LPS-neutralizing activities of these peptides were markedly reduced. Together, these observations indicate that the active region with antibacterial activity is localized at G(1) to R(18) of CAP11, whereas longer sequences (such as G(1) to E(33)) would be required for the expression of LPS-neutralizing activity. Furthermore, the C-terminal region (Y(34) to I(43)) and a disulfide bridge are not essential for the antibacterial and LPS-neutralizing activities of CAP11.
authors.affiliation: Department of Host Defense and Biochemical Research, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Daiju
authors.initials: D
authors.lastname: Okuda
authors.forename: Shin
authors.initials: S
authors.lastname: Yomogida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tamura
authors.forename: Isao
authors.initials: I
authors.lastname: Nagaoka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002460:Cell Line; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects; D006168:Guinea Pigs; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D009504:Neutrophils / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000187:drug effects; D054804:Cathelicidins
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D004220:Disulfides; D008070:Lipopolysaccharides; D054804:Cathelicidins