title: Innate immune responses of a scleractinian coral to vibriosis.
abstract: Scleractinian corals are the most basal eumetazoan taxon and provide the biological and physical framework for coral reefs, which are among the most diverse of all ecosystems. Over the past three decades and coincident with climate change, these phototrophic symbiotic organisms have been subject to increasingly frequent and severe diseases, which are now geographically widespread and a major threat to these ecosystems. Although coral immunity has been the subject of increasing study, the available information remains fragmentary, especially with respect to coral antimicrobial responses. In this study, we characterized damicornin from Pocillopora damicornis, the first scleractinian antimicrobial peptide (AMP) to be reported. We found that its precursor has a segmented organization comprising a signal peptide, an acidic proregion, and the C-terminal AMP. The 40-residue AMP is cationic, C-terminally amidated, and characterized by the presence of six cysteine molecules joined by three intramolecular disulfide bridges. Its cysteine array is common to another AMP and toxins from cnidarians; this suggests a common ancestor, as has been proposed for AMPs and toxins from arthropods. Damicornin was active in vitro against Gram-positive bacteria and the fungus Fusarium oxysporum. Damicornin expression was studied using a combination of immunohistochemistry, reverse phase HPLC, and quantitative RT-PCR. Our data show that damicornin is constitutively transcribed in ectodermal granular cells, where it is stored, and further released in response to nonpathogenic immune challenge. Damicornin gene expression was repressed by the coral pathogen Vibrio coralliilyticus. This is the first evidence of AMP gene repression in a host-Vibrio interaction.
authors.affiliation: UMR 5244, CNRS UPVD EPHE, Université de Perpignan Via Domitia, 66000 Perpignan, France.
authors.forename: Jeremie
authors.initials: J
authors.lastname: Vidal-Dupiol
authors.forename: Ophélie
authors.initials: O
authors.lastname: Ladrière
authors.forename: Delphine
authors.initials: D
authors.lastname: Destoumieux-Garzón
authors.forename: Pierre-Eric
authors.initials: PE
authors.lastname: Sautière
authors.forename: Anne-Leila
authors.initials: AL
authors.lastname: Meistertzheim
authors.forename: Eric
authors.initials: E
authors.lastname: Tambutté
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tambutté
authors.forename: David
authors.initials: D
authors.lastname: Duval
authors.forename: Laurent
authors.initials: L
authors.lastname: Fouré
authors.forename: Mehdi
authors.initials: M
authors.lastname: Adjeroud
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mitta
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D037421:Anthozoa / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D001427:Bacterial Toxins / Q000737:chemistry; D001483:Base Sequence; D004220:Disulfides / Q000737:chemistry; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D021381:Protein Transport; D014733:Vibrio / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001427:Bacterial Toxins; D004220:Disulfides