Dambek M, Eilers U, Breitenbach J, Steiger S, Büchel C, Sandmann G. Biosynthesis of fucoxanthin and diadinoxanthin and function of initial pathway genes in Phaeodactylum tricornutum.
J Exp Bot 2012;
63:5607-12. [PMID:
22888128 PMCID:
PMC3444273 DOI:
10.1093/jxb/ers211]
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Abstract
The biosynthesis pathway to diadinoxanthin and fucoxanthin was elucidated in Phaeodactylum tricornutum by a combined approach involving metabolite analysis identification of gene function. For the initial steps leading to β-carotene, putative genes were selected from the genomic database and the function of several of them identified by genetic pathway complementation in Escherichia coli. They included genes encoding a phytoene synthase, a phytoene desaturase, a ζ-carotene desaturase, and a lycopene β-cyclase. Intermediates of the pathway beyond β-carotene, present in trace amounts, were separated by TLC and identified as violaxanthin and neoxanthin in the enriched fraction. Neoxanthin is a branching point for the synthesis of both diadinoxanthin and fucoxanthin and the mechanisms for their formation were proposed. A single isomerization of one of the allenic double bounds in neoxanthin yields diadinoxanhin. Two reactions, hydroxylation at C8 in combination with a keto-enol tautomerization and acetylation of the 3'-HO group results in the formation of fucoxanthin.
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