title: Phylogeny of nuclear-encoded plastid-targeted GAPDH gene supports separate origins for the peridinin- and the fucoxanthin derivative-containing plastids of dinoflagellates.
abstract: Although most photosynthetic dinoflagellates have plastids with peridinin, the three dinoflagellate genera Karenia, Karlodinium, and Takayama possess anomalously pigmented plastids that contain fucoxanthin and its derivatives (19'-hexanoyloxy-fucoxanthin and 19'-butanoyloxy-fucoxanthin) instead of the peridinin. This pigment composition is similar to that of haptophytes. All peridinin-containing dinoflagellates investigated so far have at least two types of glyceraldehyde-3-phosphate dehydrogenase (GAPDH): cytosolic and plastid-targeted forms. In the present study, we cloned and sequenced genes encoding cytosolic and plastid-targeted GAPDH proteins from three species of the fucoxanthin derivative-containing dinoflagellates. Based on the molecular phylogeny, the plastid-targeted GAPDH genes of the fucoxanthin derivative-containing dinoflagellates were closely related to those of haptophyte algae rather than to the peridinin-containing dinoflagellates, while one of several cytosolic versions from the peridinin- and the fucoxanthin derivative-containing dinoflagellates are closely related to each other. Considering a previously reported theory that the plastid-targeted GAPDH from the peridinin-containing dinoflagellates originated by a gene duplication of the cytosolic form before the splitting of the dinoflagellate lineage, it is highly likely that the plastid-targeted GAPDH gene of the peridinin-containing dinoflagellates is original in this algal group and that in the fucoxanthin-containing dinoflagellates, the original plastid-targeted GAPDH was replaced by that of a haptophyte endosymbiont during a tertiary endosymbiosis. The present results strongly support the hypothesis that the plastids of the peridinin- and the fucoxanthin derivative-containing dinoflagellates are of separate origin.
authors.affiliation: Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa 237-0061, Japan. takishitak@jamstec.go.jp
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Takishita
authors.forename: Ken-Ichiro
authors.initials: K
authors.lastname: Ishida
authors.forename: Tadashi
authors.initials: T
authors.lastname: Maruyama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002338:Carotenoids / Q000032:analysis; D004141:Dinoflagellida / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D018087:Plastids / Q000737:chemistry; D016415:Sequence Alignment; D024341:Xanthophylls / Q000032:analysis
chemical_list: D024341:Xanthophylls; C025164:fucoxanthin; C016040:peridinin; D002338:Carotenoids; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases