Expression Analysis of theVTC2andVTC5Genes Encoding GDP-<scp>L</scp>-Galactose Phosphorylase, an Enzyme Involved in Ascorbate Biosynthesis, inArabidopsis thaliana

Gao, Yingxin; Badejo, Adebanjo A.; Shibata, Hitoshi; Sawa, Yousuke; Maruta, Takanori; Shigeoka, Shigeru; Page, Mike T.; Smirnoff, Nicholas; Ishikawa, Takahiro

doi:10.1271/bbb.110320

Cited by 41 publications

(32 citation statements)

References 32 publications

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“…Despite observing alterations in gene expression patterns of the ascorbate biosynthetic pathway under light stress in multiple studies, the upstream signal transduction pathway controlling this phenomenon is largely unknown. Studies were performed to decipher light-regulated cis-elements in rice [74] and subsequently in Arabidopsis [75]. The conserved sequences (the GT1 box and the TGACG motif) in the promoter regions of the L-galactose-1-phosphate phosphatase (GPP) and GLDH genes were found to be responsible for light induction of these genes in rice [74].…”

Section: Transcriptional Regulationmentioning

confidence: 99%

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

Rosado-Souza

Fernie

Aarabi

2020

Plants

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Cell compartmentalization allows incompatible chemical reactions and localised responses to occur simultaneously, however, it also requires a complex system of communication between compartments in order to maintain the functionality of vital processes. It is clear that multiple such signals must exist, yet little is known about the identity of the key players orchestrating these interactions or about the role in the coordination of other processes. Mitochondria and chloroplasts have a considerable number of metabolites in common and are interdependent at multiple levels. Therefore, metabolites represent strong candidates as communicators between these organelles. In this context, vitamins and similar small molecules emerge as possible linkers to mediate metabolic crosstalk between compartments. This review focuses on two vitamins as potential metabolic signals within the plant cell, vitamin C (L-ascorbate) and vitamin B1 (thiamin). These two vitamins demonstrate the importance of metabolites in shaping cellular processes working as metabolic signals during acclimation processes. Inferences based on the combined studies of environment, genotype, and metabolite, in order to unravel signaling functions, are also highlighted.

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Section: Transcriptional Regulationmentioning

confidence: 99%

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

Rosado-Souza

Fernie

Aarabi

2020

Plants

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“…In C. reinhardtii, several processes controlled by circadian rhythms are known and several 'clock genes' and their protein products have been identified (Schulze et al, 2010;Niwa et al, 2013). In higher plants, Asc accumulation and VTC2 expression are under circadian control (Gao et al, 2011) and similarly, it has also been described that Asc concentration follows a circadian rhythm in the singlecelled flagellate Euglena gracilis (Kiyota et al, 2006). In order to New Phytologist investigate whether Asc biosynthesis is also under circadian control in C. reinhardtii, we subjected cultures to four light-dark cycles (10 h : 14 h, light : dark), followed by continuous illumination for 2 d. Fig.…”

Section: Asc Biosynthesis Upon Dark-to-light Transition and During Thmentioning

confidence: 99%

Regulation of ascorbate biosynthesis in green algae has evolved to enable rapid stress‐induced response via the VTC2 gene encoding GDP‐l‐galactose phosphorylase

et al. 2017

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Ascorbate (vitamin C) plays essential roles in stress resistance, development, signaling, hormone biosynthesis and regulation of gene expression; however, little is known about its biosynthesis in algae. In order to provide experimental proof for the operation of the Smirnoff-Wheeler pathway described for higher plants and to gain more information on the regulation of ascorbate biosynthesis in Chlamydomonas reinhardtii, we targeted the VTC2 gene encoding GDP-l-galactose phosphorylase using artificial microRNAs. Ascorbate concentrations in VTC2 amiRNA lines were reduced to 10% showing that GDP-l-galactose phosphorylase plays a pivotal role in ascorbate biosynthesis. The VTC2 amiRNA lines also grow more slowly, have lower chlorophyll content, and are more susceptible to stress than the control strains. We also demonstrate that: expression of the VTC2 gene is rapidly induced by H O and O resulting in a manifold increase in ascorbate content; in contrast to plants, there is no circadian regulation of ascorbate biosynthesis; photosynthesis is not required per se for ascorbate biosynthesis; and Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range. Our work demonstrates that ascorbate biosynthesis is also highly regulated in Chlamydomonas albeit via mechanisms distinct from those previously described in land plants.

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“…Ascorbate concentrations are regulated according to demand; for example, leaf ascorbate concentrations increase under high light intensities (Gatzek et al, 2002;Bartoli et al, 2006;Dowdle et al, 2007;Yabuta et al, 2007;Bartoli et al, 2009;Gao et al, 2011) when the need for ascorbate is greatest. This is due to increased light-driven production of reactive oxygen species in photosynthesis, and this response to light is associated with changes in gene expression for several L-galactose pathway genes ( Figure 1) (Tabata et al, 2002;Dowdle et al, 2007;Yabuta et al, 2007;Gao et al, 2011;Massot et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…This is due to increased light-driven production of reactive oxygen species in photosynthesis, and this response to light is associated with changes in gene expression for several L-galactose pathway genes ( Figure 1) (Tabata et al, 2002;Dowdle et al, 2007;Yabuta et al, 2007;Gao et al, 2011;Massot et al, 2012). In nonphotosynthetic tissues, such as fruit, ascorbate concentrations are relatively stable within a cultivar, although ascorbate concentration does vary between cultivars (Ferguson and MacRae, 1992;Davey et al, 2006;Bulley et al, 2009) and this is related to changes in gene expression (Bulley et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have concentrated on changes in gene expression (Gatzek et al, 2002;Tabata et al, 2002;Dowdle et al, 2007;Yabuta et al, 2007;Gao et al, 2011;Massot et al, 2012) often over a day or longer. We have previously shown that the enzyme GDP-L-galactose phosphorylase (GGP) (encoded by the gene GGP, also known as VTC2) is at a central control point of vitamin C biosynthesis as the first committed step; overexpression of this gene in plants results in a significant increase in tissue ascorbate concentrations (Laing et al, 2007;Bulley et al, 2009Bulley et al, , 2012, suggesting it may serve a regulatory role, possibly balancing fluxes between ascorbate and GDP-L-fucose (Bonin et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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An Upstream Open Reading Frame Is Essential for Feedback Regulation of Ascorbate Biosynthesis in Arabidopsis

et al. 2015

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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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Expression Analysis of theVTC2andVTC5Genes Encoding GDP-L-Galactose Phosphorylase, an Enzyme Involved in Ascorbate Biosynthesis, inArabidopsis thaliana

Cited by 41 publications

References 32 publications

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

Regulation of ascorbate biosynthesis in green algae has evolved to enable rapid stress‐induced response via the VTC2 gene encoding GDP‐l‐galactose phosphorylase

An Upstream Open Reading Frame Is Essential for Feedback Regulation of Ascorbate Biosynthesis in Arabidopsis

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