title: A puzzling homology: a brittle star using a putative cnidarian-type luciferase for bioluminescence.
abstract: Bioluminescence relies on the oxidation of a luciferin substrate catalysed by a luciferase enzyme. Luciferins and luciferases are generic terms used to describe a large variety of substrates and enzymes. Whereas luciferins can be shared by phylogenetically distant organisms which feed on organisms producing them, luciferases have been thought to be lineage-specific enzymes. Numerous light emission systems would then have co-emerged independently along the tree of life resulting in a plethora of non-homologous luciferases. Here, we identify for the first time a candidate luciferase of a luminous echinoderm, the ophiuroidAmphiura filiformisPhylogenomic analyses identified the brittle star predicted luciferase as homologous to the luciferase of the sea pansyRenilla(Cnidaria), contradicting with the traditional viewpoint according to which luciferases would generally be of convergent origins. The similarity between theRenillaandAmphiuraluciferases allowed us to detect the latter using anti-Renillaluciferase antibodies. Luciferase expression was specifically localized in the spines which were demonstrated to be the bioluminescent organsin vivoHowever, enzymes homologous to theRenillaluciferase but unable to trigger light emission were also identified in non-luminous echinoderms and metazoans. Our findings strongly indicate that those enzymes, belonging to the haloalkane dehalogenase family, might then have been convergently co-opted into luciferases in cnidarians and echinoderms. In these two benthic suspension-feeding species, similar ecological pressures would constitute strong selective forces for the functional shift of these enzymes and the emergence of bioluminescence.
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, 7000 Mons, Belgium jerome.delroisse@umons.ac.be.
authors.forename: Jérôme
authors.identifier: 0000-0002-9233-6470
authors.initials: J
authors.lastname: Delroisse
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115 Berlin, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Ullrich-Lüter
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115 Berlin, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Blaue
authors.affiliation: Department of Marine Science, The Sven Lovén Centre for Marine Sciences - Kristineberg, University of Gothenburg, 45178 Fiskebäckskil, Sweden.
authors.forename: Olga
authors.initials: O
authors.lastname: Ortega-Martinez
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, 7000 Mons, Belgium.
authors.forename: Igor
authors.initials: I
authors.lastname: Eeckhaut
authors.affiliation: Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, 7000 Mons, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Flammang
authors.affiliation: Marine Biology Laboratory, Université Catholique de Louvain, ELI, 3 Place Croix du Sud L7.04.06, 1348 Louvain-La-Neuve, Belgium.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Mallefet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003063:Cnidaria / Q000201:enzymology* / Q000235:genetics; D004447:Echinodermata / Q000201:enzymology* / Q000235:genetics; D004789:Enzyme Activation; D015870:Gene Expression; D008156:Luciferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049410:Luciferases, Renilla / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D049449:Luminescence; D008163:Luminescent Measurements / Q000379:methods; D010802:Phylogeny; D021381:Protein Transport
chemical_list: D008156:Luciferases; D049410:Luciferases, Renilla
keywords: bioluminescence; echinoderm; evolution; luciferase