title: The light-harvesting antenna of the diatom Phaeodactylum tricornutum. Evidence for a diadinoxanthin-binding subcomplex.
abstract: Diatoms differ from higher plants by their antenna system, in terms of both polypeptide and pigment contents. A rapid isolation procedure was designed for the membrane-intrinsic light harvesting complexes (LHC) of the diatom Phaeodactylum tricornutum to establish whether different LHC subcomplexes exist, as well to determine an uneven distribution between them of pigments and polypeptides. Two distinct fractions were separated that contain functional oligomeric complexes. The major and more stable complex ( approximately 75% of total polypeptides) carries most of the chlorophyll a, and almost only one type of carotenoid, fucoxanthin. The minor complex, carrying approximately 10-15% of the total antenna chlorophyll and only a little chlorophyll c, is highly enriched in diadinoxanthin, the main xanthophyll cycle carotenoid. The two complexes also differ in their polypeptide composition, suggesting specialized functions within the antenna. The diadinoxanthin-enriched complex could be where the de-epoxidation of diadinoxanthin into diatoxanthin mostly occurs.
authors.affiliation: Organismes Photosynthétiques et Environnement, CNRS, Département de Biologie, Ecole Normale Supérieure, Paris, France. ggugliel@biologie.ens.fr
authors.forename: Gérard
authors.initials: G
authors.lastname: Guglielmi
authors.forename: Johann
authors.initials: J
authors.lastname: Lavaud
authors.forename: Bernard
authors.initials: B
authors.lastname: Rousseau
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Etienne
authors.forename: Jean
authors.initials: J
authors.lastname: Houmard
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ruban
mesh_terms: D002338:Carotenoids / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002734:Chlorophyll / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D002850:Chromatography, Gel; D017377:Diatoms / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D046911:Macromolecular Substances; D010839:Phytoplankton / Q000378:metabolism; D024341:Xanthophylls / Q000378:metabolism*
chemical_list: D045342:Light-Harvesting Protein Complexes; D046911:Macromolecular Substances; D024341:Xanthophylls; D002734:Chlorophyll; C033808:diadinoxanthin; D002338:Carotenoids