An upstream open reading frame is essential for feedback regulation of ascorbate biosynthesis in arabidopsis

Laing, William A., Martínez-Sánchez, Marcela, Wright, Michele A., Bulley, Sean M., Brewster, Di, Dare, Andrew P., Rassam, Maysoon, Wang, Daisy, Storey, Roy, Macknight, Richard C., & Hellens, Roger P. (2015) An upstream open reading frame is essential for feedback regulation of ascorbate biosynthesis in arabidopsis. The Plant Cell, 27(3), pp. 772-786.

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Ascorbate (vitamin C) is an essential antioxidant and enzyme cofactor in both plants and animals. Ascorbate concentration is tightly regulated in plants, partly to respond to stress. Here, we demonstrate that ascorbate concentrations are determined via the posttranscriptional repression of GDP-l-galactose phosphorylase (GGP), a major control enzyme in the ascorbate biosynthesis pathway. This regulation requires a cis-acting upstream open reading frame (uORF) that represses the translation of the downstream GGP open reading frame under high ascorbate concentration. Disruption of this uORF stops the ascorbate feedback regulation of translation and results in increased ascorbate concentrations in leaves. The uORF is predicted to initiate at a noncanonical codon (ACG rather than AUG) and encode a 60- to 65-residue peptide. Analysis of ribosome protection data from Arabidopsis thaliana showed colocation of high levels of ribosomes with both the uORF and the main coding sequence of GGP. Together, our data indicate that the noncanonical uORF is translated and encodes a peptide that functions in the ascorbate inhibition of translation. This posttranslational regulation of ascorbate is likely an ancient mechanism of control as the uORF is conserved in GGP genes from mosses to angiosperms.

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11 citations in Web of Science®

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ID Code: 84587
Item Type: Journal Article
Refereed: Yes
Keywords: vitamin C, translational regulation, non canonical transcription start
DOI: 10.1105/tpc.114.133777
ISSN: 1532-298X
Divisions: Current > Research Centres > Centre for Tropical Crops and Biocommodities
Current > Schools > School of Earth, Environmental & Biological Sciences
Past > QUT Faculties & Divisions > Faculty of Science and Technology
Current > Institutes > Institute for Future Environments
Copyright Owner: © 2015 American Society of Plant Biologists
Deposited On: 01 Jun 2015 02:20
Last Modified: 02 Jun 2015 01:56

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