Significance of the <i>cis–trans</i> isomerization of early intermediates in the carotene biosynthetic pathway

Paneth, Piotr; Soundararajan, M.; O’Leary, Marion H.

doi:10.1002/poc.610051202

Cited by 3 publications

(4 citation statements)

References 13 publications

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“…Alternatively, the reason for the emergence of a different desaturation pathway is a requirement to maintain the carotenoid intermediates in a cis-configuration. Support for the latter hypothesis comes from the finding that cis-isomers of the early biosynthetic intermediates are more stable than the corresponding trans-isomers (Paneth et al, 1992).…”

Section: Phytoene Desaturation In Plants and Bacteriamentioning

confidence: 61%

Analysis in Vitro of the Enzyme CRTISO Establishes a Poly-cis-Carotenoid Biosynthesis Pathway in Plants

et al. 2004

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Most enzymes in the central pathway of carotenoid biosynthesis in plants have been identified and studied at the molecular level. However, the specificity and role of cis-trans-isomerization of carotenoids, which occurs in vivo during carotene biosynthesis, remained unresolved. We have previously cloned from tomato (Solanum lycopersicum) the CrtISO gene, which encodes a carotene cis-trans-isomerase. To study the biochemical properties of the enzyme, we developed an enzymatic in vitro assay in which a purified tomato CRTISO polypeptide overexpressed in Escherichia coli cells is active in the presence of an E. coli lysate that includes membranes. We show that CRTISO is an authentic carotene isomerase. Its catalytic activity of cis-totrans isomerization requires redox-active components, suggesting that isomerization is achieved by a reversible redox reaction acting at specific double bonds. Our data demonstrate that CRTISO isomerizes adjacent cis-double bonds at C7 and C9 pairwise into the trans-configuration, but is incapable of isomerizing single cis-double bonds at C9 and C9#. We conclude that CRTISO functions in the carotenoid biosynthesis pathway in parallel with z-carotene desaturation, by converting 7,9,9#-tri-cisneurosporene to 9#-cis-neurosporene and 7#9#-di-cis-lycopene into all-trans-lycopene. These results establish that in plants carotene desaturation to lycopene proceeds via cis-carotene intermediates.Carotenoids comprise a large group of terpenoid pigments synthesized by all plants algae and cyanobacteria as well as by several nonphotosynthetic bacteria and fungi. Carotenoids fulfill indispensable functions in photosynthesis (Frank et al., 1999), and in plants they also provide colors to flowers and fruits. Dietary carotenoids are essential precursors to vitamin A, and they are implicated in reducing the occurrence of certain cancers and cardiovascular diseases, possibly by serving as antioxidants and free radical scavengers (for review, see Demmig-Adams and Adams, 2002; Fraser and Bramley, 2004).Our understanding of the carotenoid biosynthetic pathway in plants has been advanced greatly in the past decade, mainly due to cloning of many of the genes for enzymes involved in the pathway. The first carotenoid in the pathway is phytoene, a product of condensation of two geranylgeranyl diphosphate (GGDP) molecules. The colorless phytoene undergoes four consecutive dehydrogenation reactions that introduce four double bonds in conjugation, giving rise to the red polyene chromophore of lycopene, the precursor of a diverse group of cyclic carotenoids. In plants, two desaturases, phytoene desaturase (PDS) and z-carotene desaturase (ZDS), carry out these reactions, whereas in bacteria all four dehydrogenation reactions are carried out by a single gene product, named CRTI (for review, see Hirschberg, 2001). Most plant carotenoids carry trans-configured double bonds. However, specific cis-isomers do exist, for example, 9-cis-neoxanthin in the light-harvesting complex (Liu et al., 2004;Snyder et al., 2004) and 9-c...

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Section: Phytoene Desaturation In Plants and Bacteriamentioning

confidence: 61%

Analysis in Vitro of the Enzyme CRTISO Establishes a Poly-cis-Carotenoid Biosynthesis Pathway in Plants

et al. 2004

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“…An explanation proposed is that the early intermediates of carotenoid synthesis are more energetically stable as cis rather than as trans -isomers. 262 Alternatively, it was proposed that one of the advantages of the poly- cis pathway is that the use of redox cofactors by the desaturases (PDS and ZDS) and isomerases (CRTISO) of the poly- cis pathway ties lycopene formation to the availability of redox cofactors, hence, the metabolic state of the photosynthetic cell. 160 This is a persuasive argument which is reminiscent of other regulatory models proposed for the regulation of secondary metabolism.…”

Section: Discussionmentioning

confidence: 99%

“…Why would cyanobacteria and plants use four separate enzymes and a convoluted mechanism to form lycopene when bacteria can accomplish the same goal with one single enzyme, CRTI. An explanation proposed is that the early intermediates of carotenoid synthesis are more energetically stable as cis rather than as trans isomers . Alternatively, it was proposed that one of the advantages of the poly- cis pathway is that the use of redox cofactors by the desaturases (PDS and ZDS) and isomerases (CRTISO) of the poly- cis pathway ties lycopene formation to the availability of redox cofactors and, hence, the metabolic state of the photosynthetic cell .…”

Section: Concluding Remarksmentioning

confidence: 99%

Mechanistic Aspects of Carotenoid Biosynthesis

2013

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“…In contrast to this wide experimental and theoretical studies on main carotenoids, to our knowledge only a semiempirical method was used to theoretically study phytofluene [17].…”

Section: Introduction Smentioning

confidence: 98%

Theoretical investigation of carotenoid ultraviolet spectra

Martins

Durães

Sales

et al. 2008

Int J of Quantum Chemistry

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ABSTRACT:We have determined the band-gaps of the main carotenoids present in poly(methyl)methacrylate/buriti blends, namely, trans-␤-carotene, 13-cis-␤-carotene, 9-cis-␤-carotene, phytofluene, and zeaxanthin. Semiempirical, model Hamiltonian, and density functional calculations were carried out to study these structures. The geometries were fully optimized using AM1, PM3, and B3LYP/6-31G(d,p) methods. The TD-DFT and ZINDO/S methods were applied for the calculation of the electronic absorption spectra of the optimized B3LYP geometries. The calculated spectra using the polarizable continuum model for the solvent effects were compared with the available experimental.

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Significance of the cis–trans isomerization of early intermediates in the carotene biosynthetic pathway

Cited by 3 publications

References 13 publications

Analysis in Vitro of the Enzyme CRTISO Establishes a Poly-cis-Carotenoid Biosynthesis Pathway in Plants

Analysis in Vitro of the Enzyme CRTISO Establishes a Poly-cis-Carotenoid Biosynthesis Pathway in Plants

Mechanistic Aspects of Carotenoid Biosynthesis

Theoretical investigation of carotenoid ultraviolet spectra

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