d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

Saito, Kazumi; Nick, Jerry A.; Loewus, Frank A.

doi:10.1104/pp.94.3.1496

Cited by 48 publications

(28 citation statements)

References 12 publications

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“…However, there are radioactive tracer data indicating that inversion of the glucose carbon skeleton does not occur during AsA biosynthesis in higher plants (4). A noninversion pathway was proposed that invokes D-glucosone and L-sorbosone as intermediates (5,6), but no recent evidence has been reported for this pathway (2).…”

mentioning

confidence: 99%

Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis

Conklin

Norris

Wheeler

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

369

303

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Vitamin C (L-ascorbic acid; AsA) acts as a potent antioxidant and cellular reductant in plants and animals. AsA has long been known to have many critical physiological roles in plants, yet its biosynthesis is only currently being defined. A pathway for AsA biosynthesis that features GDP-mannose and L-galactose has recently been proposed for plants. We have isolated a collection of AsAdeficient mutants of Arabidopsis thaliana that are valuable tools for testing of an AsA biosynthetic pathway. The bestcharacterized of these mutants (vtc1) contains Ϸ25% of wildtype AsA and is defective in AsA biosynthesis. By using a combination of biochemical, molecular, and genetic techniques, we have demonstrated that the VTC1 locus encodes a GDP-mannose pyrophosphorylase (mannose-1-P guanyltransferase). This enzyme provides GDP-mannose, which is used for cell wall carbohydrate biosynthesis and protein glycosylation as well as for AsA biosynthesis. In addition to genetically defining the first locus involved in AsA biosynthesis, this work highlights the power of using traditional mutagenesis techniques coupled with the Arabidopsis Genome Initiative to rapidly clone physiologically important genes.

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mentioning

confidence: 99%

Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis

Conklin

Norris

Wheeler

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

369

303

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“…Loewus (15) has proposed an alternative pathway in which L-AA is synthesized from D-glucose via L-sorbosone. The presence of an enzyme able to convert L-sorbosone to L-AA with concomitant reduction of NADP was demonstrated in bean and spinach leaves (16,17). Conceivably, these distinct routes might be present in different subcellular compartments or in different plant species.…”

mentioning

confidence: 99%

Isolation of a cDNA Coding forl-Galactono-γ-Lactone Dehydrogenase, an Enzyme involved in the Biosynthesis of Ascorbic Acid in Plants

Østergaard¹,

Persiau

Davey

et al. 1997

Journal of Biological Chemistry

141

127

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L-Galactono-␥-lactone dehydrogenase (EC 1.3.2.3; GLDase), an enzyme that catalyzes the final step in the biosynthesis of L-ascorbic acid was purified 1693-fold from a mitochondrial extract of cauliflower (Brassica oleracea, var. botrytis) to apparent homogeneity with an overall yield of 1.1%. The purification procedure consisted of anion exchange, hydrophobic interaction, gel filtration, and fast protein liquid chromatography. The enzyme had a molecular mass of 56 kDa estimated by gel filtration chromatography and SDS-polyacrylamide gel electrophoresis and showed a pH optimum for activity between pH 8.0 and 8.5, with an apparent K m of 3.3 mM for L-galactono-␥-lactone. Based on partial peptide sequence information, polymerase chain reaction fragments were isolated and used to screen a cauliflower cDNA library from which a cDNA encoding GLDase was isolated. The deduced mature GLDase contained 509 amino acid residues with a predicted molecular mass of 57,837 Da. Expression of the cDNA in yeast produced a biologically active protein displaying GLDase activity. Furthermore, we identified a substrate for the enzyme in cauliflower extract, which co-eluted with L-galactono-␥-lactone by high-performance liquid chromatography, suggesting that this compound is a naturally occurring precursor of L-ascorbic acid biosynthesis in vivo.

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“…1B). The osones glucosone and sorbosone are the proposed intermediate substrates in this pathway Saito et al, 1990 . However, an enzymatic activity that is able to convert L-sorbosone to ASA has been partially purified from both spinach and bean .…”

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confidence: 99%

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

1997

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d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

Cited by 48 publications

References 12 publications

Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis

Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis

Isolation of a cDNA Coding forl-Galactono-γ-Lactone Dehydrogenase, an Enzyme involved in the Biosynthesis of Ascorbic Acid in Plants

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

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