Carotenoids biosynthetic pathway

Elncidation of the Erwinia uredovora carotenoid biosynthetic pathway by functional analysis of gene prodncts expressed in Escherichia coif, J Bacteriol, 172, 6704-12. 

FIGURE 5.3.1 Parts of the isoprenoid pathways to carotenoids. 1 = MEP pathway. 2 = GGPP synthesis. 3 = Carotenoid biosynthetic pathway. 4 = Carotenoid degradative pathways. Enzyme abbreviations and enzyme activities are defined in Table 5.3.1. 

FIGURE 5.3.2 Carotenoid biosynthetic pathways in plants. Enzyme abbreviations and enzyme activities are defined in Table 5.3.1. 

Understanding mechanisms controlling metabolon localization in plastids of different membrane architectures Little is known about metabolon structure, assembly, and membrane targeting. The carotenoid biosynthetic pathway exists on plastid membranes. However, plastids have different membrane architectures and therefore tissue- and plastid-specific differences in membrane targeting of the biosynthetic metabolon can be expected. Localization in chloroplasts that harbor both thylakoid and envelope membranes differs from the envelope membranes in endosperm amy-loplasts. In fact, localization on both thylakoid and envelope membranes implies that the carotenoid pathway is really not a single pathway, but a duplicated pathway that may very well have membrane-specific roles with regard to functions in primary and secondary metabolism. 

Schmidt-Dannert, C., Umeno, D., and Arnold, R, Molecular breeding of carotenoid biosynthetic pathways, Nat. Biotechnol. 18, 750, 2000. 

Gallagher, C.E. et al.. Gene duplication in the carotenoid biosynthetic pathway preceded evolution of the grasses (Poaceae). Plant Physiol. 135, 1776, 2004. 

Li, Z.H. et ah. Cloning and characterization of a maize cDNA encoding phytoene desaturase, an enzyme of the carotenoid biosynthetic pathway. Plant Mol. Biol. 30, 269, 1996. 

Verdoes, J.C. et al., Metabolic engineering of the carotenoid biosynthetic pathway in the yeast Xanthophyllomyces dendrorhous Phaffia rhodozyma), Appl. Environ. Microbiol., 69, 3728, 2003. 

Figure 73. The carotenoid biosynthetic pathway. Enzymes are named according to the designation of their genes Ccs, capsanthin-capsorubin synthase CrtL-b, lycopene-b-cyclase CrtL-e, lycopene-e-cyclase CrtR-b, b-ring hydroxylase, CrtR-e, e-ring hydroxylase DMADP, dimethylallyl diphosphate GGDP, geranylgeranyl diphosphate Ggps, geranylgeranyl-diphosphate synthase IDP, isopentenyl diphosphate Ipi, IDP isomerase Pds, phytoene desaturase Psy, phytoene synthase Vde, violaxanthin de-epoxidase Zds, z-carotene desaturase Zep, zeaxanthin epoxidase. (From van den Berg and others 2000.)...

During fruit ripening, the pepper carotenoid biosynthetic pathway is able to make a variety of carotenoids including [ -carotene, violaxanthin, capsombin, and capsanthin (Fig. 8.2) [18]. The latter two are ketoxanthophylls specific to peppers and are not found in other plants. Capsanthin and capsombin accumulate in red-colored peppers, while P-carotene is responsible for orange-colored fruit (Fig. 8.1). 

The carotenoid biosynthetic pathway leads to products such as vitamin A and its precursors carotene, responsible for the color of carrots or salmon, and lycopene, the color agent in tomatoes (Figure 11.12). Pathway products are sought for a variety of applications in food, medicine, and materials. Genes in the pathway from different organisms were combined and heterologously expressed in E. coli, a non-... 

C. Schmidt-Dannert, D. Umeno, and F. H. Arnold, Molecular breeding of carotenoid biosynthetic pathways, Nature Biotechnol. 2000, 18, 750-753. 

Fig. 4 Reconstruction of the carotenoids biosynthetic pathway in S. cerevisiae. Heterologous activities t-HMGl 3 hydroxy-3-methylglutaryl-coenzymeA, ctrE geranylgeranyldiphosphate synthase (from Xanthophyllomyces dendrorhous), Ctrl phytoene desaturase, ctrYB bifunctional enzyme phytoene synthase and lycopene cyclase. Endogenous yeast activities ISIS I geranylgeranyldiphosphate synthase. Metabolites IPP isopentenyl diphosphate, GPP geranyl diphosphate, FPP famesyl-diphosphate, GGPP geranylgeranyl diphosphate...

Bioregulatory agents such as MPTA and DCPTA possess two distinct properties stimulation of the carotenoid biosynthetic pathway and inhibition of the cyclization of the acyclic to the cyclic carotenoids.The stimulation appear to be an indirect effect whereas the inhibitory effect is a direct one. By application of the compounds at lower concentrations at the early stages of its developmental phase, the inhibitory effect can be minmized resulting in the enhancement of desirable color normally associated with the crop. 

Fig. /. Carotenoid biosynthetic pathway in plants. For clarity, only the portion of the biosynthetic pathway starting with lycopene is shown. Enzymes are indicated by numbers as follows I, /J-cyclase 2, e-cyclase 3, / -ring hydroxylase 4, e-ring hydroxylase 5, zeaxanthin epoxidase and violaxanthin de-epoxidase enzymes 6, neoxanthin forming enzyme. The location of the lutJy lut2, and aba mutations are indicated. Carotenoids that typically accumulate in photosynthetic tissues are given in capital letters.

Bishop N I, Urbig T and Senger H (1995) Complete separation of the beta, epsilon- and beta, beta-carotenoid biosynthetic pathways by a unique mutation of the lycopene cyclase in the green alga, Scenedesmus obliquus. FEBS Letters 367 158-162... 

Komori M, Ghosh R, Takaichi S, Hu Y, Mizoguchi T, Koyama Y and Kuki M (1998) A null lesion in the rhodopin 3,4-desaturase of Rhodospirillum rubmm unmasks a cryptic branch of the carotenoid biosynthetic pathway. Biochemistry 37 8987-8994... 

Hunter CN, Hundle BS, Hearst JE, Lang HP, Gardiner AT, Takaichi S and Cogdell RJ (1994) Introduction of new carotenoids into the bacterial photosynthetic apparatus by combining the carotenoid biosynthetic pathways of Erwinia herbicola and Rhodobacter sphaeroides. J Bacteriol 176 3692-3697... 

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