한빛사논문
- 조회3,783
Abstract
-carotene | carotenoid hydroxylase | cytochrome P450 | xanthophyl | substrate channeling )
Joonyul Kim *
and Dean DellaPenna *
*Department of Biochemistry and Molecular Biology and Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824-1319
Communicated by Jan A. D. Zeevaart, Michigan State University, East Lansing, MI, December 27, 2005 (received for review October 11, 2005)
Lutein, a dihydroxy derivative of -carotene (
,
-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: - and -ring cyclizations and hydroxylation of each ring at the C-3 position. Three carotenoid hydroxylases have already been identified in Arabidopsis, two nonheme diiron -ring monooxygenases (the B1 and B2 loci) that primarily catalyze hydroxylation of the -ring of ,-carotenoids and one heme-containing monooxygenase (CYP97C1, the LUT1 locus) that catalyzes hydroxylation of the -ring of ,-carotenoids. In this study, we demonstrate that Arabidopsis CYP97A3 (the LUT5 locus) encodes a fourth carotenoid hydroxylase with major in vivo activity toward the -ring of -carotene (,-carotene) and minor activity on the -rings of -carotene (,-carotene). A cyp97a3-null allele, lut5-1, causes an accumulation of -carotene at a level equivalent to -carotene in wild type, which is stably incorporated into photosystems, and a 35% reduction in -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 -carotene, -ring hydroxylation of -carotene by CYP97A3 to produce zeinoxanthin, followed by -ring hydroxylation of zeinoxanthin by CYP97C1 to produce lutein.
Author contributions: J.K. and D.D. designed research; J.K. performed research; J.K. and D.D. analyzed data; and J.K. and D.D. wrote the paper.
Conflict of interest statement: No conflicts declar...
논문정보
- Research article
- 2006년 02월 (BRIC 등록일 )
- 국외 연구진
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