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Literature summary for 1.14.99.63 extracted from

  • Bai, C.; Berman, J.; Farre, G.; Capell, T.; Sandmann, G.; Christou, P.; Zhu, C.
    Reconstruction of the astaxanthin biosynthesis pathway in rice endosperm reveals a metabolic bottleneck at the level of endogenous beta-carotene hydroxylase activity (2017), Transgenic Res., 26, 13-23 .
    View publication on PubMed

Application

Application Comment Organism
nutrition rice endosperm can be engineered to produce nutritionally important ketocarotenoids. The limited activity of endogenous beta-carotene hydroxylases causes a bottleneck in the extended ketocarotenoid pathway that must be overcome in order to maximize flux towards target ketocarotenoid molecules Chlamydomonas reinhardtii

Cloned(Commentary)

Cloned (Comment) Organism
recombinant coexpression of Zea mays phytoene synthase 1 (ZmPSY1), Pantoea ananatis phytoene desaturase (PaCRTI), and a synthetic Chlamydomonas reinhardtii beta-carotene ketolase (sCrBKT) in transgenic rice plants, in grain endosperm of Oryza sativa cv. EYI-105 Chlamydomonas reinhardtii
transgenic rice endosperm expressing phytoene synthase, phytoene desaturase and beta-carotene ketolase accumulates large amounts of canthaxanthin and adonirubin, plus additional ketocarotenoids in smaller amounts, such as astaxanthin Chlamydomonas reinhardtii

Protein Variants

Protein Variants Comment Organism
additional information recombinant coexpression of Zea mays phytoene synthase 1 (ZmPSY1), Pantoea ananatis phytoene desaturase (PaCRTI), and a synthetic Chlamydomonas reinhardtii beta-carotene ketolase (sCrBKT) in transgenic rice plants, in grain endosperm, under the control of endosperm-specific promoters. The resulting grains predominantly accumulate the diketocarotenoids canthaxanthin, adonirubin and astaxanthin as well as low levels of monoketocarotenoids. The predominance of canthaxanthin and adonirubin indicates the presence of a hydroxylation bottleneck in the ketocarotenoid pathway. Synthetic beta-carotene ketolase gene is sufficient to produce ketocarotenoids in both the callus and endosperm when there is strong flux through the early part of the pathway, but the heterologous beta-carotene ketolase overwhelms the endogenous beta-carotene hydroxylase activity and skews the metabolic profiles strongly in favor in ketolation thus promoting the accumulation of canthaxanthin and adonirubin rather than astaxanthin. Quantitative real-time RT-PCR analysis is used to compare the expression levels of the relative endogenous beta-carotene hydroxylase gene (OsBCH) in the endosperm of all four lines. Carotenoid biosynthesis pathway in plants, overview Chlamydomonas reinhardtii

Organism

Organism UniProt Comment Textmining
Chlamydomonas reinhardtii Q4VKB4
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-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
beta-carotene + 2 O2 + 2 reduced acceptor
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Chlamydomonas reinhardtii canthaxanthin + 3 H2O + 2 acceptor
-
?
zeaxanthin + 2 O2 + 2 reduced acceptor
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Chlamydomonas reinhardtii astaxanthin + 3 H2O + 2 acceptor
-
?

Synonyms

Synonyms Comment Organism
beta-carotene ketolase
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Chlamydomonas reinhardtii
bkt
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Chlamydomonas reinhardtii
sCrBKT
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Chlamydomonas reinhardtii

General Information

General Information Comment Organism
physiological function in the extended carotenoid pathway, astaxanthin is derived from beta-carotene by the 3-hydroxylation and 4-ketolation of both ionone end groups. These reactions are catalyzed by beta-carotene hydroxylase and beta-carotene ketolase, respectively. The hydroxylation reaction is widespread in higher plants, but ketolation is mostly restricted to bacteria, fungi, and some unicellular green algae Chlamydomonas reinhardtii