title: Dicynthaurin: an antimicrobial peptide from hemocytes of the solitary tunicate, Halocynthia aurantium.
abstract: We isolated a novel antimicrobial peptide, dicynthaurin, from hemocytes of a tunicate, Halocynthia aurantium. The native peptide had a mass of approximately 6.2 kDa and was composed of two 30-residue monomers without sequence homology to any previously identified peptides (ILQKAVLDCLKAAGSSLSKAAITAIYNKIT). Most cynthaurin molecules were C-terminally amidated and were linked covalently by a single cystine disulfide bond. When performed in membrane-mimetic environments, circular dichroism studies of dicynthaurin revealed largely alpha-helical conformations. Dicynthaurin's broad-spectrum activity encompassed Gram-positive (Micrococcus luteus, Staphylococcus aureus, Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), but not Candida albicans, a fungus. Although dicynthaurin was purified from a marine invertebrate, its antimicrobial activity was optimal at NaCl concentrations below 100 mM. This suggests that the antimicrobial actions of this molecule may take place intracellularly (e.g., within a phagosome) rather than extracellularly.
authors.affiliation: Department of Life Science, Hoseo University, Asan City, Chungnam-Do, South Korea. leeih@office.hoseo.ac.kr
authors.forename: I H
authors.initials: IH
authors.lastname: Lee
authors.forename: Y S
authors.initials: YS
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Kim
authors.forename: C R
authors.initials: CR
authors.lastname: Kim
authors.forename: T
authors.initials: T
authors.lastname: Hong
authors.forename: L
authors.initials: L
authors.lastname: Menzel
authors.forename: L M
authors.initials: LM
authors.lastname: Boo
authors.forename: J
authors.initials: J
authors.lastname: Pohl
authors.forename: M A
authors.initials: MA
authors.lastname: Sherman
authors.forename: A
authors.initials: A
authors.lastname: Waring
authors.forename: R I
authors.initials: RI
authors.lastname: Lehrer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification*; D002942:Circular Dichroism; D019281:Dimerization; D004151:Dipeptides / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D006434:Hemocytes / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014020:Tissue Extracts / Q000737:chemistry; D014561:Urochordata / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004151:Dipeptides; D010455:Peptides; D014020:Tissue Extracts; C437228:dicynthaurin