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| Content Provider | PubMed Central |
|---|---|
| Author | Kim, Joonyul Dellapenna, Dean |
| Copyright Year | 2006 |
| Abstract | Lutein, a dihydroxy derivative of α-carotene (β,ε-carotene), is the most abundant carotenoid in photosynthetic plant tissues where it plays important roles in light-harvesting complex-II structure and function. The synthesis of lutein from lycopene requires at least four distinct enzymatic reactions: β- and ε-ring cyclizations and hydroxylation of each ring at the C-3 position. Three carotenoid hydroxylases have already been identified in Arabidopsis, two nonheme diiron β-ring monooxygenases (the B1 and B2 loci) that primarily catalyze hydroxylation of the β-ring of β,β-carotenoids and one heme-containing monooxygenase (CYP97C1, the LUT1 locus) that catalyzes hydroxylation of the ε-ring of β,ε-carotenoids. In this study, we demonstrate that Arabidopsis CYP97A3 (the LUT5 locus) encodes a fourth carotenoid hydroxylase with major in vivo activity toward the β-ring of α-carotene (β,ε-carotene) and minor activity on the β-rings of β-carotene (β,β-carotene). A cyp97a3-null allele, lut5-1, causes an accumulation of α-carotene at a level equivalent to β-carotene in wild type, which is stably incorporated into photosystems, and a 35% reduction in β-carotene-derived xanthophylls. That lut5-1 still produces 80% of wild-type lutein levels, indicating at least one of the other carotene hydroxylases, can partially compensate for the loss of CYP97A3 activity. From these data, we propose a model for the preferred pathway for lutein synthesis in plants: ring cyclizations to form α-carotene, β-ring hydroxylation of α-carotene by CYP97A3 to produce zeinoxanthin, followed by ε-ring hydroxylation of zeinoxanthin by CYP97C1 to produce lutein. |
| Related Links | http://dx.doi.org/10.1073/pnas.0511207103 |
| Ending Page | 3479 |
| Page Count | 6 |
| Starting Page | 3474 |
| File Format | |
| ISSN | 00278424 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 9 |
| Volume Number | 103 |
| Language | English |
| Publisher | National Academy of Sciences |
| Publisher Date | 2006-02-28 |
| Access Restriction | Open |
| Rights Holder | National Academy of Sciences |
| Subject Keyword | General Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Multidisciplinary |
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