This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Secondary Metabolites Biosynthesis → Terpenoids Biosynthesis → Carotenoids Biosynthesis|
|Biosynthesis → Secondary Metabolites Biosynthesis → Terpenoids Biosynthesis → Tetraterpenoids Biosynthesis|
Expected Taxonomic Range: Spermatophyta
General information on carotenoids:
Carotenoids with cyclic ends are integral constituents of plants, algae and cyanobacteria photosynthetic reaction centers [Goodwin80, Young93]. Animals, including humans, cannot synthesize carotenoids, although they are an essential source of retinoids and vitamin A. These isoprenoids pigments are lipid-soluble and are involved in a variety of functions including: protection against photooxidative stress through energy-dissipation of excess light absorbed by the antenna pigments; light-harvest for photosynthesis; the prominent lutein, as well as zeaxanthin, are involved in the reduction of cataract and macular degeneration; others are exploited as coloring agents in flowers and fruits to attract pollinators (and in industry as food colorant) and agents of seed dispersal; finally they are precursors for the plant growth hormone abscisic acid and vitamin A (for a succinct review of the applications of carotenoids, see [Cunningham98]).
Carotenoids are C40 isoprenoids which consist of eight isoprene units and can be divided in two major groups: carotene and xanthophylls. Carotenes are linear or cyclized hydrocarbons such as lycopene, α-carotene and β-carotene. Xanthophylls are oxygenated derivatives (epoxy, keto or hydroxyl groups) of carotenes; for example: lutein, zeaxanthin. The carotenoid composition varies from species to species; the concentration and composition of xanthophylls are affected by light intensity and the accumulation of specific carotenoids in fruit and flower chromoplasts is a highly, developmentally regulated process [Fraser94, Giuliano93]. Important carotenoids variations are observed during fruit ripening (for review, see [Ronen99]). Higher plant chloroplasts typically accumulate lutein, β-carotene, violaxanthin and neoxanthin in the thylakoid membrane-bound photosystems [Peter91, Ryberg93]. β-Carotene is generally found in the reaction center where it plays a critical photoprotective role by quenching triplet chlorophyll and singlet oxygen, and can undergo rapid degradation during photooxidation [Young93a]. Adjacent to the reaction centers, in the core complex proteins, β-carotene and lutein can be found [Peter91, Bassi93]. Finally, the surrounding antenna complexes contain xanthophylls (lutein, violaxanthin and neoxanthin) [Peter91, Bassi93]. In the chromoplasts of ripening fruits and flower petals, and in the chloroplasts of senescing leaves, the carotenoids are found in membranes or in oil bodies or other structures within the stroma.
General information on paprika carotenoids:
Capsanthin and capsorubin are two disctinctive xanthophylls unique to the Capsicum family. They contain a 'cyclopentane' ring (cyclo- = ring; -pent- = five carbons; -ane = single bonds). These xanthophylls are responsible for the bright red colors of ripe peppers. The major red color in paprika (Capsicum annuum, pepper) comes from the carotenoids capsanthin and capsorubin, while the yellow-orange color is from beta-carotene and violaxanthin [Reeves87]. Capsanthin which represents one of the major carotenoid in ripe pepper fruits, contributes up to 60% of the total carotenoids. Capsanthin and capsorubin increase proportionally with increased fruit maturation; capsanthin is the more stable of the two [Kanner77]. Both capsanthin and capsorubin have demonstrated significant antioxidant activity. A recent study found that capsanthin's radical-scavenging action was as strong as that of β-carotene, lutein, and zeaxanthin. In addition, it was shown to be more resistant to decomposition, and retained its antioxidant properties longer than the other carotenoids. About 70 - 80% of the capsanthin was found to be 'esterified' with various fatty acids; these esterified xanthophylls were also determined to have antioxidant properties [Matsufuji98].
Capsanthin and capsorubin
AlBabili00: Al-Babili S, Hugueney P, Schledz M, Welsch R, Frohnmeyer H, Laule O, Beyer P (2000). "Identification of a novel gene coding for neoxanthin synthase from Solanum tuberosum." FEBS Lett 485(2-3);168-72. PMID: 11094161
Bouvier94: Bouvier F, Hugueney P, d'Harlingue A, Kuntz M, Camara B (1994). "Xanthophyll biosynthesis in chromoplasts: isolation and molecular cloning of an enzyme catalyzing the conversion of 5,6-epoxycarotenoid into ketocarotenoid." Plant J 6(1);45-54. PMID: 7920703
Fraser94: Fraser PD, Truesdale MR, Bird CR, Schuch W, Bramley PM (1994). "Carotenoid Biosynthesis during Tomato Fruit Development (Evidence for Tissue-Specific Gene Expression)." Plant Physiol 105(1);405-413. PMID: 12232210
HorneroMendez00: Hornero-Mendez D, Gomez-Ladron De Guevara R, Minguez-Mosquera MI (2000). "Carotenoid biosynthesis changes in five red pepper (Capsicum annuum L.) cultivars during ripening. Cultivar selection for breeding." J Agric Food Chem 48(9);3857-64. PMID: 10995282
Jeknic12: Jeknic Z, Morre JT, Jeknic S, Jevremovic S, Subotic A, Chen TH (2012). "Cloning and functional characterization of a gene for capsanthin-capsorubin synthase from tiger lily (Lilium lancifolium Thunb. 'Splendens')." Plant Cell Physiol 53(11);1899-912. PMID: 23008421
Ronen99: Ronen G, Cohen M, Zamir D, Hirschberg J (1999). "Regulation of carotenoid biosynthesis during tomato fruit development: expression of the gene for lycopene epsilon-cyclase is down-regulated during ripening and is elevated in the mutant Delta." Plant J 17(4);341-51. PMID: 10205893
Ryberg93: Ryberg, H., Ryberg, M., Sundqvist, C. (1993). "Plastid ultrastructure and development." In "Pigment-protein complexes in plastids: synthesis and assembly', C.Sundqvist and M. Ryberg, eds, London: Academic Press, pp. 25-62.
Young93a: Young AJ (1993). "Factors that affect the carotenoid composition of higer plants and algae." In 'Carotenoids in photosynthesis' A.J. Young and G. Britton, eds, London: Chapman and Hall, pp. 161-205.
Baroli03: Baroli I, Do AD, Yamane T, Niyogi KK (2003). "Zeaxanthin accumulation in the absence of a functional xanthophyll cycle protects Chlamydomonas reinhardtii from photooxidative stress." Plant Cell 15(4);992-1008. PMID: 12671093
Bouvier96: Bouvier F, d'Harlingue A, Hugueney P, Marin E, Marion-Poll A, Camara B (1996). "Xanthophyll biosynthesis. Cloning, expression, functional reconstitution, and regulation of beta-cyclohexenyl carotenoid epoxidase from pepper (Capsicum annuum)." J Biol Chem 271(46);28861-7. PMID: 8910532
Chae11: Chae, Lee (2011). "The functional annotation of protein sequences was performed by the in-house Ensemble Enzyme Prediction Pipeline (E2P2, version 1.0). E2P2 systematically integrates results from three molecular function annotation algorithms using an ensemble classification scheme. For a given genome, all protein sequences are submitted as individual queries against the base-level annotation methods. The individual methods rely on homology transfer to annotate protein sequences, using single sequence (BLAST, E-value cutoff <= 1e-30, subset of SwissProt 15.3) and multiple sequence (Priam, November 2010; CatFam, version 2.0, 1% FDR profile library) models of enzymatic functions. The base-level predictions are then integrated into a final set of annotations using an average weighted integration algorithm, where the weight of each prediction from each individual method was determined via a 0.632 bootstrap process over 1000 rounds of testing. The training and testing data for E2P2 and the BLAST reference database were drawn from protein sequences with experimental support of existence, compiled from SwissProt release 15.3."
Marin96: Marin E, Nussaume L, Quesada A, Gonneau M, Sotta B, Hugueney P, Frey A, Marion-Poll A (1996). "Molecular identification of zeaxanthin epoxidase of Nicotiana plumbaginifolia, a gene involved in abscisic acid biosynthesis and corresponding to the ABA locus of Arabidopsis thaliana." EMBO J 15(10);2331-42. PMID: 8665840
Niyogi97: Niyogi KK, Bjorkman O, Grossman AR (1997). "Chlamydomonas Xanthophyll Cycle Mutants Identified by Video Imaging of Chlorophyll Fluorescence Quenching." Plant Cell 9(8);1369-1380. PMID: 12237386
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