In the green algaHaematococcus pluvialis the ketocarotenoid astaxanthin accumulates under stress conditions. Astaxanthin is a red carotenoid pigment which possess antioxidative activity. We have cloned the gene for β-C-4 oxygenase (β-carotene ketolase) from the green algaeH. pluvialis. The cloning method took advantage of a strain ofE. coli which was genetically engineered to produce β-carotene. An expression cDNA library ofH. pluvialis was transfected to cells of this strain and visually screened for brown-red pigmented colonies. One colony out of 100,000 transformants showed color change due to accumulation of canthaxanthin. The cDNA clone in this transformant colony encodes the enzyme β-C-4 oxygenase that catalyzes the conversion of β carotene to canthaxanthin via echinenone. This enzyme does not convert zeaxanthin to astaxanthin. It is concluded that inH. pluvialis astaxanthin is synthesized via canthaxanthin and therefore an additional enzyme is predicted, which converts canthaxanthin to astaxanthin.
|Number of pages||4|
|State||Published - 8 May 1995|
Bibliographical noteFunding Information:
Acknowledgments: This research was supported by Grant 034-7342 from the Ernest D. Bergman Fund for Science. T. Lotan is supported by the L. Eshkol grant of the Ministry of Science, National Council for Research and Development. We wish to thank Dr. A. Young for supplying the carotenoid standards and Dr. A. Mandelbaum and Dr. J. Katzir for the mass spectrometry analysis.
- Haematococcus pluvialis
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology
- Cell Biology