Publication: Formation of carboxylated and decarboxylated betalains in ripening grains of Chenopodium quinoa by a dual dioxygenase
Authors
Henarejos Escudero, Paula ; Martínez-Rodríguez, Pedro ; Gomez-Pando, Luz Rayda ; Gandía Herrero, Fernando ; García Carmona, Francisco
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Publisher
Oxford University Press, Society for Experimental Biology
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DOI
https://doi.org/10.1093/jxb/erac151
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info:eu-repo/semantics/article
Description
© 2022, The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.
This document is the Published version of a Published Work that appeared in final form in Journal of Experimental Botany. To access the final edited and published work see https://doi.org/10.1093/jxb/erac151
Abstract
Chenopodium quinoa (quinoa) is a pseudo-cereal that forms part of the cultural heritage of Andean countries, and its grains have high nutritional value and potential health benefits. Betalains are nitrogenous water-soluble pigments and bioactive molecules that contribute to these health-promoting properties. Betalains are restricted to plants of the order Caryophyllales, to which quinoa belongs. A new family of betalains has been discovered in the form of unconventional decarboxylated pigments. Here, we show that these pigments accumulate in ripening quinoa grains of fluorescent nature, and are putatively based on a dopamine-cleaving activity. This study describes for the first time the purification and molecular and functional characterization of a 4,5-dopamine extradiol dioxygenase enzyme from plants. It is a monomeric protein with a molecular mass of 34.5 kDa characterized by chromatography, electrophoresis, and time-offlight mass spectrometry. We demonstrate that this key enzyme has a dual function in a square-shaped biosynthetic pathway towards the formation of both carboxylated and decarboxylated pigments. Enzyme kinetic properties are characterized for the production of 6-decarboxy-betalamic acid and 3,4-dihydroxy-l-phenylalanine-derived betalamic acid, the two structural units of plant pigment in nature. The profile of multiple betalains present in quinoa grains has been reproduced in one-pot bioreactors containing the novel enzyme and two competing substrates
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Citation
Journal of Experimental Botany, Vol. 73, No. 12 pp. 4170–4183, 2022
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