L-Ascorbic Acid Metabolism in the Ascorbate-Deficient Arabidopsis Mutant vtc1

Conklin, Patricia L.; Pallanca, Jane E.; Smirnoff, Nicholas

doi:10.1104/pp.115.3.1277

Cited by 202 publications

(153 citation statements)

References 30 publications

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“…However, similar to the pmm-12 mutant, cyt1 could not be rescued by exogenously applied AsA (24), suggesting that in both cases the lack of AsA is not sufficient to explain the developmental arrest and subsequent cell death. The cyt1 mutant is allelic to vtc1, a mutant deficient in its AsA biosynthesis (12) that was isolated by virtue of its sensitivity to oxidative stress (47). In marked contrast to the lethality caused by cyt1 mutations, vtc1 plants are viable and fertile, indicating that the vtc1 mutation is weak.…”

Section: Map-based Cloning Of the Pmm-12mentioning

confidence: 99%

“…Therefore, we measured AsA levels in pmm-12 after transfer to restrictive temperature, using the ascorbate-deficient vtc1 mutant (11,12) as a reference. In wild type plants, AsA levels increased significantly after transfer to 28°C, whereas in pmm-12 plants they remained relatively stable and amounted to only 20 -50% of wild type levels.…”

Section: Identification Of a Ts Cell Deathmentioning

confidence: 99%

“…1). As a consequence, vtc1 plants contain only ϳ25% of wild type AsA levels (11,12). Very recently, evidence has been provided for the role of PMM in AsA biosynthesis in plants (3).…”

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confidence: 99%

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A Temperature-sensitive Mutation in the Arabidopsis thaliana Phosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

Hoeberichts

Vaeck

Kiddle

et al. 2008

Journal of Biological Chemistry

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Eukaryotic phosphomannomutases (PMMs) catalyze the interconversion of mannose 6-phosphate to mannose 1-phosphate and are essential to the biosynthesis of GDP-mannose. As such, plant PMMs are involved in ascorbic acid (AsA) biosynthesis and N-glycosylation. We report on the conditional phenotype of the temperature-sensitive Arabidopsis thaliana pmm-12 mutant. Mutant seedlings were phenotypically similar to wild type seedlings when grown at 16 -18°C but died within several days after transfer to 28°C. This phenotype was observed throughout both vegetative and reproductive development. Protein extracts derived from pmm-12 plants had lower PMM protein and enzyme activity levels. In vitro biochemical analysis of recombinant proteins showed that the mutant PMM protein was compromised in its catalytic efficiency (K cat /K m ). Despite significantly decreased AsA levels in pmm-12 plants, AsA deficiency could not account for the observed phenotype. Since, at restrictive temperature, total glycoprotein patterns were altered and glycosylation of protein-disulfide isomerase was perturbed, we propose that a deficiency in protein glycosylation is responsible for the observed cell death phenotype.

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Section: Map-based Cloning Of the Pmm-12mentioning

confidence: 99%

Section: Identification Of a Ts Cell Deathmentioning

confidence: 99%

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A Temperature-sensitive Mutation in the Arabidopsis thaliana Phosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

Hoeberichts

Vaeck

Kiddle

et al. 2008

Journal of Biological Chemistry

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“…GDP-Man synthesis is one of the rate-limiting steps in AsA synthesis, as shown in plants with reduced amounts of functional VTC1 (Conklin et al, 1997). Therefore, the influence of kjc mutations on AsA level in seedlings was also investigated.…”

Section: Asa Levels In Kjc Mutantsmentioning

confidence: 99%

“…VITAMIN C DEFECTIVE1 (VTC1)/CYTOKINESIS DEFECTIVE1 (CYT1; hereafter, VTC1 indicates VTC1/CYT1 protein) has been identified as the major form of GMPP in Arabidopsis, and evidence for its key role in AsA synthesis comes from a number of different studies: In Arabidopsis thaliana, the vtc1-1 mutant, a leaky mutant for the VTC1 gene, exhibits a 70% decrease in AsA level (Conklin et al, 1997(Conklin et al, , 1999) and a CONSTITUTIVE PHO-TOMORPHOGENESIS9 (COP9) signalosome subunit, CSN5B, downregulates AsA level through the degradation of VTC1 in the dark (Wang et al, 2013b). In tomato (Solanum lycopersicum), metabolic engineering to increase pyrophosphate (PPi) levels substantially decreased AsA quantity, as it promoted pyrophosphorolysis of GDP-Man into Man 1-P and GTP by GMPP (Osorio et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

et al. 2015

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Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.

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PlantL-ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

Davey

Montagu

Inzé

et al. 2000

J. Sci. Food Agric.

1,080

173

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Humans are unable to synthesise L‐ascorbic acid (L‐AA, ascorbate, vitamin C), and are thus entirely dependent upon dietary sources to meet needs. In both plant and animal metabolism, the biological functions of L‐ascorbic acid are centred around the antioxidant properties of this molecule. Considerable evidence has been accruing in the last two decades of the importance of L‐AA in protecting not only the plant from oxidative stress, but also mammals from various chronic diseases that have their origins in oxidative stress. Evidence suggests that the plasma levels of L‐AA in large sections of the population are sub‐optimal for the health protective effects of this vitamin. Until quite recently, little focus has been given to improving the L‐AA content of plant foods, either in terms of the amounts present in commercial crop varieties, or in minimising losses prior to ingestion. Further, while L‐AA biosynthesis in animals was elucidated in the 1960s,1 it is only very recently that a distinct biosynthetic route for plants has been proposed.2 The characterisation of this new pathway will undoubtedly provide the necessary focus and impetus to enable fundamental questions on plant L‐AA metabolism to be resolved. This review focuses on the role of L‐AA in metabolism and the latest studies regarding its biosynthesis, tissue compartmentalisation, turnover and catabolism. These inter‐relationships are considered in relation to the potential to improve the L‐AA content of crops. Methodology for the reliable analysis of L‐AA in plant foods is briefly reviewed. The concentrations found in common food sources and the effects of processing, or storage prior to consumption are discussed. Finally the factors that determine the bioavailability of L‐AA and how it may be improved are considered, as well as the most important future research needs. © 2000 Society of Chemical Industry

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L-Ascorbic Acid Metabolism in the Ascorbate-Deficient Arabidopsis Mutant vtc1

Cited by 202 publications

References 30 publications

A Temperature-sensitive Mutation in the Arabidopsis thaliana Phosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

A Temperature-sensitive Mutation in the Arabidopsis thaliana Phosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

PlantL-ascorbic acid: chemistry, function, metabolism, bioavailability and effects of processing

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