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 (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 | 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 | UniProt | Comment | Textmining |
---|---|---|---|
Chlamydomonas reinhardtii | Q4VKB4 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
beta-carotene + 2 O2 + 2 reduced acceptor | - |
Chlamydomonas reinhardtii | canthaxanthin + 3 H2O + 2 acceptor | - |
? | |
zeaxanthin + 2 O2 + 2 reduced acceptor | - |
Chlamydomonas reinhardtii | astaxanthin + 3 H2O + 2 acceptor | - |
? |
Synonyms | Comment | Organism |
---|---|---|
beta-carotene ketolase | - |
Chlamydomonas reinhardtii |
bkt | - |
Chlamydomonas reinhardtii |
sCrBKT | - |
Chlamydomonas reinhardtii |
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 |