This Article Full Text Full Text (PDF) All Versions of this Article: 15/6/1320    most recent tpc.011403v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (31) Citing Articles via Google Scholar Google Scholar Articles by Tian, L. Articles by DellaPenna, D. Search for Related Content PubMed PubMed Citation Articles by Tian, L. Articles by DellaPenna, D. Agricola Articles by Tian, L. Articles by DellaPenna, D.

Functional Analysis of - and -Ring Carotenoid Hydroxylases in Arabidopsis

Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824

¹ To whom correspondence should be addressed. E-mail dellapen{at}msu.edu; fax 517-353-9334

Lutein and zeaxanthin are dihydroxy xanthophylls that are produced from their corresponding carotene precursors by the action of - and -ring carotenoid hydroxylases. Two genes that encode -ring hydroxylases (-hydroxylases 1 and 2) have been identified in the Arabidopsis genome and are highly active toward -rings but only weakly active toward -rings. A third distinct activity required for -ring hydroxylation has been defined by mutation of the LUTEIN1 (LUT1) locus, but LUT1 has not yet been cloned. To address the individual and overlapping functions of the three Arabidopsis carotenoid hydroxylase activities in vivo, T-DNA knockout mutants corresponding to -hydroxylases 1 and 2 (b1 and b2, respectively) were isolated and all possible hydroxylase mutant combinations were generated. -Hydroxylase single mutants do not exhibit obvious growth defects and have limited impact on carotenoid composition relative to the wild type, suggesting that the encoded proteins have a significant degree of functional redundancy in vivo. Surprisingly, the b1 b2 double mutant, which lacks both known -hydroxylase enzymes, still contains significant levels of -carotene–derived xanthophylls, suggesting that additional -ring hydroxylation activity exists in vivo. The phenotype of double and triple hydroxylase mutants indicates that at least a portion of this activity resides in the LUT1 gene product. Despite the severe reduction of -carotene–derived xanthophylls (up to 90% in the lut1 b1 b2 triple mutant), the double and triple hydroxylase mutants still contain at least 50% of the wild-type amount of hydroxylated -rings. This finding suggests that it is the presence of minimal amounts of hydroxylated -rings, rather than minimal amounts of specific -carotene–derived xanthophylls, that are essential for light-harvesting complex II assembly and function in vivo. The carotenoid profiles in wild-type seeds and the effect of single and multiple hydroxylase mutations are distinct from those in photosynthetic tissues, indicating that the activities of each gene product differ in the two tissues. Overall, the hydroxylase mutants provide insight into the unexpected overlapping activity of carotenoid hydroxylases in vivo.

This article has been cited by other articles:

				C. Andre and C. Benning Arabidopsis Seedlings Deficient in a Plastidic Pyruvate Kinase Are Unable to Utilize Seed Storage Compounds for Germination and Establishment Plant Physiology, December 1, 2007; 145(4): 1670 - 1680. [Abstract] [Full Text] [PDF]

				L. Dall'Osto, A. Fiore, S. Cazzaniga, G. Giuliano, and R. Bassi Different Roles of {alpha}- and -Branch Xanthophylls in Photosystem Assembly and Photoprotection J. Biol. Chem., November 30, 2007; 282(48): 35056 - 35068. [Abstract] [Full Text] [PDF]

				M. P. Johnson, M. Havaux, C. Triantaphylides, B. Ksas, A. A. Pascal, B. Robert, P. A. Davison, A. V. Ruban, and P. Horton Elevated Zeaxanthin Bound to Oligomeric LHCII Enhances the Resistance of Arabidopsis to Photooxidative Stress by a Lipid-protective, Antioxidant Mechanism J. Biol. Chem., August 3, 2007; 282(31): 22605 - 22618. [Abstract] [Full Text] [PDF]

				L. U. Gilliland, M. Magallanes-Lundback, C. Hemming, A. Supplee, M. Koornneef, L. Bentsink, and D. DellaPenna Colloquium Paper: Genetic basis for natural variation in seed vitamin E levels in Arabidopsis thaliana PNAS, December 5, 2006; 103(49): 18834 - 18841. [Abstract] [Full Text] [PDF]

				J. Kim and D. DellaPenna Defining the primary route for lutein synthesis in plants: The role of Arabidopsis carotenoid beta-ring hydroxylase CYP97A3 PNAS, February 28, 2006; 103(9): 3474 - 3479. [Abstract] [Full Text] [PDF]

				P. Schaub, S. Al-Babili, R. Drake, and P. Beyer Why Is Golden Rice Golden (Yellow) Instead of Red? Plant Physiology, May 1, 2005; 138(1): 441 - 450. [Abstract] [Full Text] [PDF]

				S. E. Sattler, L. U. Gilliland, M. Magallanes-Lundback, M. Pollard, and D. DellaPenna Vitamin E Is Essential for Seed Longevity and for Preventing Lipid Peroxidation during Germination PLANT CELL, June 1, 2004; 16(6): 1419 - 1432. [Abstract] [Full Text] [PDF]

				L. Tian, V. Musetti, J. Kim, M. Magallanes-Lundback, and D. DellaPenna The Arabidopsis LUT1 locus encodes a member of the cytochrome P450 family that is required for carotenoid {epsilon}-ring hydroxylation activity PNAS, January 6, 2004; 101(1): 402 - 407. [Abstract] [Full Text] [PDF]