Phytoene desaturase (lycopene-forming)

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Phytoene desaturase (lycopene-forming)
Pantoea-ananatis-crti 4dgk.png
Crystallographic structure of a bacterial phytoene desaturase monomer from Pantoea ananatis. [1]
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EC no. 1.3.99.31
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Phytoene desaturase (lycopene-forming) (CrtI, four-step phytoene desaturase) (EC 1.3.99.31, 15-cis-phytoene:acceptor oxidoreductase (lycopene-forming)) are enzymes found in archaea, bacteria and fungi that are involved in carotenoid biosynthesis. [2] They catalyze the conversion of colorless 15-cis-phytoene into a bright red lycopene in a biochemical pathway called the poly-trans pathway. The same process in plants and cyanobacteria utilizes four separate enzymes in a poly-cis pathway. [3]

Contents

Biochemistry

The conversion of phytoene to lycopene in plants and cyanobacteria (left) compared to bacteria and fungi(right). Phytoene desaturation PLOS ONE.png
The conversion of phytoene to lycopene in plants and cyanobacteria (left) compared to bacteria and fungi(right).

Bacterial phytoene desaturases were shown to require FAD as a cofactor for their function. [4] During the chemical reaction in total four additional double bonds are introduced into phytoene:

15-cis-phytoene + 4 acceptor all-trans-lycopene + 4 reduced acceptor (overall reaction)
(1a) 15-cis-phytoene + acceptor all-trans-phytofluene + reduced acceptor
(1b) all-trans-phytofluene + acceptor all-trans-zeta-carotene + reduced acceptor
(1c) all-trans-zeta-carotene + acceptor all-trans-neurosporene + reduced acceptor:
(1d) all-trans-neurosporene + acceptor all-trans-lycopene + reduced acceptor

Applications

In 2000 it was discovered that the gene insertion of a bacterial phytoene desaturase into transgenic tomatoes increased the lycopene content without the need to alter several of the plants enzymes. [5] This approach was later used in rice to increase its β-carotene content resulting in the Golden Rice project.

See also

Related Research Articles

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Golden rice is a variety of rice produced through genetic engineering to biosynthesize beta-carotene, a precursor of vitamin A, in the edible parts of the rice. It is intended to produce a fortified food to be grown and consumed in areas with a shortage of dietary vitamin A. Vitamin A deficiency causes xerophthalmia, a range of eye conditions from night blindness to more severe clinical outcomes such as keratomalacia and corneal scars, and permanent blindness. Additionally, vitamin A deficiency also increases risk of mortality from measles and diarrhea in children. In 2013, the prevalence of deficiency was the highest in sub-Saharan Africa, and South Asia.

<span class="mw-page-title-main">Carotenoid</span> Class of chemical compounds; yellow, orange or red plant pigments

Carotenoids are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Over 1,100 identified carotenoids can be further categorized into two classes – xanthophylls and carotenes.

<span class="mw-page-title-main">Carotenoid oxygenase</span>

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CRT is the gene cluster responsible for the biosynthesis of carotenoids. Those genes are found in eubacteria, in algae and are cryptic in Streptomyces griseus.

In enzymology, a carotene 7,8-desaturase (EC 1.14.99.30) is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Damascenone</span> Chemical compound

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<span class="mw-page-title-main">Phytoene</span> Chemical compound

Phytoene is a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate (GGPP) by the action of the enzyme phytoene synthase. The two GGPP molecules are condensed together followed by removal of diphosphate and proton shift leading to the formation of phytoene.

Phytoene synthase is a transferase enzyme involved in the biosynthesis of carotenoids. It catalyzes the conversion of geranylgeranyl pyrophosphate to phytoene. This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">15-Cis-phytoene desaturase</span> Class of enzymes

15-cis-phytoene desaturases, are enzymes involved in the carotenoid biosynthesis in plants and cyanobacteria. Phytoene desaturases are membrane-bound enzymes localized in plastids and introduce two double bonds into their colorless substrate phytoene by dehydrogenation and isomerize two additional double bonds. This reaction starts a biochemical pathway involving three further enzymes called the poly-cis pathway and leads to the red colored lycopene. The homologous phytoene desaturase found in bacteria and fungi (CrtI) converts phytoene directly to lycopene by an all-trans pathway.

9,9'-dicis-zeta-carotene desaturase is an enzyme with systematic name 9,9'-dicis-zeta-corotene:quinone oxidoreductase. This enzyme catalyses the following chemical reaction

4,4'-Diapophytoene desaturase is an enzyme with systematic name 15-cis-4,4'-diapophytoene:FAD oxidoreductase. This enzyme catalyses the following chemical reaction

All-trans-zeta-carotene desaturase is an enzyme with systematic name all-trans-zeta-carotene:acceptor oxidoreductase. This enzyme catalyses the following chemical reaction

1-Hydroxycarotenoid 3,4-desaturase is an enzyme with systematic name 1-hydroxy-1,2-dihydrolycopene:acceptor oxidoreductase. This enzyme catalyses the following chemical reaction

Phytoene desaturase (neurosporene-forming) is an enzyme with systematic name 15-cis-phytoene:acceptor oxidoreductase (neurosporene-forming). This enzyme catalyses the following chemical reaction

Phytoene desaturase (zeta-carotene-forming) is an enzyme with systematic name 15-cis-phytoene:acceptor oxidoreductase (zeta-carotene-forming). This enzyme catalyses the following chemical reaction

Phytoene desaturase (3,4-didehydrolycopene-forming) is an enzyme with systematic name 15-cis-phytoene:acceptor oxidoreductase (3,4-didehydrolycopene-forming). This enzyme catalyses the following chemical reaction

Prolycopene isomerase is an enzyme with systematic name 7,9,7',9'-tetracis-lycopene cis-trans-isomerase. This enzyme catalyses the following chemical reaction

Beta-carotene isomerase is an enzyme with systematic name beta-carotene 9-cis-all-trans isomerase. This enzyme catalyses the following chemical reaction

Lycopene β-cyclase is an enzyme with systematic name carotenoid beta-end group lyase (decyclizing). This enzyme catalyses the following chemical reaction

Phytoene desaturase may refer to:

References

  1. ↑ PDB: 4dgk ​; Schaub P; Yu Q; Gemmecker S; Poussin-Courmontagne P; Mailliot J; McEwen AG; Ghisla S; Al-Babili S; Cavarelli J; Beyer P (2012). "On the Structure and Function of the Phytoene Desaturase CRTI from Pantoea ananatis, a Membrane-Peripheral and FAD-Dependent Oxidase/Isomerase". PLOS ONE. 7 (6): e39550. doi: 10.1371/journal.pone.0039550 . PMC   3382138 . PMID   22745782.
  2. ↑ Fraser, P.D.; Misawa, N.; Linden, H.; Yamano, S.; Kobayashi, K.; Sandmann, G. (1992). "Expression in Escherichia coli, purification, and reactivation of the recombinant Erwinia uredovora phytoene desaturase". J. Biol. Chem. 267 (28): 19891–19895. doi: 10.1016/S0021-9258(19)88639-8 . PMID   1400305.
  3. ↑ Moise AR, Al-Babili S, Wurtzel ET (31 October 2013). "Mechanistic aspects of carotenoid biosynthesis". Chemical Reviews. 114 (1): 164–193. doi:10.1021/cr400106y. PMC   3898671 . PMID   24175570.
  4. ↑ Dailey TA; Dailey HA (May 1998). "Identification of an FAD superfamily containing protoporphyrinogen oxidases, monoamine oxidases, and phytoene desaturase. Expression and characterization of phytoene desaturase of Myxococcus xanthus". Journal of Biological Chemistry. 273 (22): 13658–13662. doi: 10.1074/jbc.273.22.13658 . PMID   9593705.
  5. ↑ Romer, S.; Fraser, P.D.; Kiano, J.W.; Shipton, C.A.; Misawa, N; Schuch, W.; Bramley, P.M. (2000). "Elevation of provitamin A content of transgenic tomato plants". Nature Biotechnology. 18 (6): 666–669. doi:10.1038/76523. PMID   10835607. S2CID   11801214.
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