title: Two hepcidin-like antimicrobial peptides in Barramundi Lates calcarifer exhibit differing tissue tropism and are induced in response to lipopolysaccharide.
abstract: Genes encoding two hepcidin-like antimicrobial peptides were discovered in Barramundi, Lates calcarifer (barramundi, Giant sea perch). Analysis of the coding regions indicated that genes for each hepcidin comprised 3 exons and 2 introns. The deduced amino acid sequences for each molecule resulted in a protein comprising a signal sequence of 24 aa in each case, coupled to a prepropeptide of 75 aa for hepcidin 1 and 78 aa for hepcidin 2. A cleavage site was identified in each prepropetide at amino acid 64 with the cleavage motif--QKR/QS--resulting in mature peptides of 25 and 28 amino acids respectively. Each mature peptide contained 8 conserved cysteine residues and 3 dimensional modeling predicted a β-hairpin and β-sheet structure characteristic of human Liver Expressed Antimicrobial Peptide (LEAP). Analysis of the deduced amino acid sequences by BLAST with phylogenetic supported indicated that hepcidin 1 was a HAMP1-type peptide closely related to hepcidins identified in other Perciformes (Micropterus and Pseudosciaena), whilst hepcidin 2 was a HAMP2-type peptide most similar to a hepcidin previously identified in black rock fish (Sebastes schlegeli). Both hepcidin genes were inducible in barramundi following intraperitoneal injection with lipopolysaccharide, with elevated expression detected in liver and head kidney 3 h post IP injection for hepcidin 1 and in liver only for hepcidin 2. The elevated expression was transient with return to normal levels within 24-48 h. No significant expression of either peptide was detected in spleen, skin or gill following IP injection with LPS.
authors.affiliation: The University of Queensland, Centre for Marine Science, School of Biological Sciences, Brisbane QLD4072, Australia. a.barnes@uq.edu.au
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Barnes
authors.forename: Brendan
authors.initials: B
authors.lastname: Trewin
authors.forename: Natale
authors.initials: N
authors.lastname: Snape
authors.forename: E Charlotte E
authors.initials: EC
authors.lastname: Kvennefors
authors.forename: Justice C F
authors.initials: JC
authors.lastname: Baiano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D029941:Fish Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D020869:Gene Expression Profiling; D064451:Hepcidins; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism
chemical_list: D023181:Antimicrobial Cationic Peptides; D018076:DNA, Complementary; D029941:Fish Proteins; C578702:HAMP protein, human; D064451:Hepcidins; D008070:Lipopolysaccharides