Xanthophyll biosynthesis in chromoplasts: isolation and molecular cloning of an enzyme catalyzing the conversion of 5,6-epoxycarotenoid into ketocarotenoid.
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.
Bouvier
F
F
Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Strasbourg, France.
Hugueney
P
P
d'Harlingue
A
A
Kuntz
M
M
Camara
B
B
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
D018076:DNA, Complementary; D010940:Plant Proteins; D002338:Carotenoids; D010088:Oxidoreductases; C086535:CCS protein, Capsicum annuum; D014975:Lutein