title: Xanthophyll biosynthesis in chromoplasts: isolation and molecular cloning of an enzyme catalyzing the conversion of 5,6-epoxycarotenoid into ketocarotenoid.
abstract: The late steps of carotenoid biosynthesis in plants involve the formation of xanthophylls. Little is known about the enzymology of these steps. This paper reports the purification to homogeneity of a xanthophyll biosynthetic enzyme from Capsicum annuum chromoplasts, which catalyzes the conversion of the ubiquitous 5,6-epoxycarotenoids, antheraxanthin and violaxanthin, into capsanthin and capsorubin, respectively. Owing to its bifunctionality, the name capsanthin-capsorubin synthase is proposed for this new enzyme. The purified enzyme is a monomer with a molecular mass of 50 kDa. Antibodies raised against this enzyme allowed the isolation of a full-length cDNA clone encoding a capsanthin capsorubin synthase high molecular weight precursor. The primary deduced structure reveals the presence of a consensus nucleotide binding site. The capsanthin-capsorubin synthase gene is specifically expressed during chromoplast development in fruits accumulating ketocarotenoids, but not in mutants impaired in this biosynthetic step.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Strasbourg, France.
authors.forename: F
authors.initials: F
authors.lastname: Bouvier
authors.forename: P
authors.initials: P
authors.lastname: Hugueney
authors.forename: A
authors.initials: A
authors.lastname: d'Harlingue
authors.forename: M
authors.initials: M
authors.lastname: Kuntz
authors.forename: B
authors.initials: B
authors.lastname: Camara
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002212:Capsicum / Q000201:enzymology* / Q000235:genetics; D002338:Carotenoids / Q000378:metabolism*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D014975:Lutein / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D010940:Plant Proteins; D010946:Plants, Medicinal; D018087:Plastids / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D002338:Carotenoids; D010088:Oxidoreductases; C086535:CCS protein, Capsicum annuum; D014975:Lutein