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Watkins JL, Li M, McQuinn RP, Chan KX, McFarlane HE, Ermakova M, Furbank RT, Mares D, Dong C, Chalmers KJ, Sharp P, Mather DE, Pogson BJ. A GDSL Esterase/Lipase Catalyzes the Esterification of Lutein in Bread Wheat. Plant Cell 2019; 31:3092-3112. [PMID: 31575724 PMCID: PMC6925002 DOI: 10.1105/tpc.19.00272] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/01/2019] [Accepted: 09/30/2019] [Indexed: 05/08/2023]
Abstract
Xanthophylls are a class of carotenoids that are important micronutrients for humans. They are often found esterified with fatty acids in fruits, vegetables, and certain grains, including bread wheat (Triticum aestivum). Esterification promotes the sequestration and accumulation of carotenoids, thereby enhancing stability, particularly in tissues such as in harvested wheat grain. Here, we report on a plant xanthophyll acyltransferase (XAT) that is both necessary and sufficient for xanthophyll esterification in bread wheat grain. XAT contains a canonical Gly-Asp-Ser-Leu (GDSL) motif and is encoded by a member of the GDSL esterase/lipase gene family. Genetic evidence from allelic variants of wheat and transgenic rice (Oryza sativa) calli demonstrated that XAT catalyzes the formation of xanthophyll esters. XAT has broad substrate specificity and can esterify lutein, β-cryptoxanthin, and zeaxanthin using multiple acyl donors, yet it has a preference for triacylglycerides, indicating that the enzyme acts via transesterification. A conserved amino acid, Ser-37, is required for activity. Despite xanthophylls being synthesized in plastids, XAT accumulated in the apoplast. Based on analysis of substrate preferences and xanthophyll ester formation in vitro and in vivo using xanthophyll-accumulating rice callus, we propose that disintegration of the cellular structure during wheat grain desiccation facilitates access to lutein-promoting transesterification.plantcell;31/12/3092/FX1F1fx1.
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Affiliation(s)
- Jacinta L Watkins
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Ming Li
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Ryan P McQuinn
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Kai Xun Chan
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Heather E McFarlane
- School of Biosciences, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Maria Ermakova
- Australian Research Council Centre of Excellence in Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Robert T Furbank
- Australian Research Council Centre of Excellence in Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Daryl Mares
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Chongmei Dong
- Plant Breeding Institute and Sydney Institute of Agriculture, The University of Sydney, Cobbitty, New South Wales 2570, Australia
| | - Kenneth J Chalmers
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Peter Sharp
- Plant Breeding Institute and Sydney Institute of Agriculture, The University of Sydney, Cobbitty, New South Wales 2570, Australia
| | - Diane E Mather
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia
| | - Barry J Pogson
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
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