title: An antimicrobial peptide from the skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae).
abstract: A 25 amino-acid-residue, C-terminally alpha-amidated peptide with antimicrobial activity, which has been termed fallaxin, was isolated in high yield from the norepinephrine-stimulated skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae). The amino acid sequence of the peptide (Gly-Val-Val-Asp-Ile-Leu-Lys-Gly-Ala-Ala-Lys-Asp-Ile-Ala-Gly-His-Leu-Ala-Ser-Lys-Val-Met-Asn-Lys-Leu.NH2) shows structural similarity with members of the ranatuerin-2 family previously isolated from the skins of frogs of the genus Rana that are only distantly related to the Leptodactylidae. This observation is consistent with the hypothesis that many frog skin antimicrobial peptides are related evolutionarily, having arisen from multiple duplications of an ancestral gene that existed before the radiation of the different families. Fallaxin inhibited the growth of reference strains of Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae) but with relatively low potency (MIC> or =20 microM) and was inactive against the Gram-positive bacterium (Staphylococcus aureus) and the yeast Candida albicans. The hemolytic activity of fallaxin was very low (HC50>200 microM). A second peptide, comprising residues (1-22) of fallaxin, was also isolated from the skin secretions but this component was inactive against the microorganisms tested.
authors.affiliation: Departments of Microbiology and Immunology and of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Rollins-Smith
authors.forename: Jay D
authors.initials: JD
authors.lastname: King
authors.forename: Per F
authors.initials: PF
authors.lastname: Nielsen
authors.forename: Agnes
authors.initials: A
authors.lastname: Sonnevend
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*; D001001:Anura / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000187:drug effects; D005260:Female; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D012867:Skin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D023181:Antimicrobial Cationic Peptides