Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants

Carole L Linster; Tara A Gomez; Kathryn C Christensen; Lital N Adler; Brian D Young; Charles Brenner; Steven G Clarke

doi:10.1074/jbc.M702094200

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Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants

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Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants

Carole L Linster, Tara A Gomez, Kathryn C Christensen, Lital N Adler, Brian D Young, Charles Brenner and Steven G Clarke

The Journal of biological chemistry, Vol.282(26), pp.18879-18885

06/29/2007

DOI: 10.1074/jbc.M702094200

PMCID: PMC2556065

PMID: 17462988

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Abstract

The first committed step in the biosynthesis of L-ascorbate from D-glucose in plants requires conversion of GDP-L-galactose to L-galactose 1-phosphate by a previously unidentified enzyme. Here we show that the protein encoded by VTC2, a gene mutated in vitamin C-deficient Arabidopsis thaliana strains, is a member of the GalT/Apa1 branch of the histidine triad protein superfamily that catalyzes the conversion of GDP-L-galactose to L-galactose 1-phosphate in a reaction that consumes inorganic phosphate and produces GDP. In characterizing recombinant VTC2 from A. thaliana as a specific GDP-L-galactose/GDP-D-glucose phosphorylase, we conclude that enzymes catalyzing each of the ten steps of the Smirnoff-Wheeler pathway from glucose to ascorbate have been identified. Finally, we identify VTC2 homologs in plants, invertebrates, and vertebrates, suggesting that a similar reaction is used widely in nature.

Amino Acid Sequence

Arabidopsis Proteins - genetics

Galactose - metabolism

Phosphoric Monoester Hydrolases - genetics

Phosphorylation

Arabidopsis - enzymology

Molecular Sequence Data

Substrate Specificity

Ascorbic Acid - metabolism

Phosphorylases - metabolism

Arabidopsis - genetics

Arabidopsis Proteins - metabolism

Ascorbic Acid - biosynthesis

Glucose - metabolism

Guanosine Diphosphate - metabolism

Phosphoric Monoester Hydrolases - metabolism

Phosphorylases - genetics

Details

Title: Subtitle: Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants
Creators: Carole L Linster - Department of Chemistry and Biochemistry, Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA
Tara A Gomez
Kathryn C Christensen
Lital N Adler
Brian D Young
Charles Brenner
Steven G Clarke
Resource Type: Journal article
Publication Details: The Journal of biological chemistry, Vol.282(26), pp.18879-18885
DOI: 10.1074/jbc.M702094200
PMID: 17462988
PMCID: PMC2556065
NLM abbreviation: J Biol Chem
ISSN: 0021-9258
eISSN: 1083-351X
Publisher: United States
Grant note: R01 CA075954-11 / NCI NIH HHS R01 AG018000 / NIA NIH HHS AG018000 / NIA NIH HHS GM026020 / NIGMS NIH HHS R37 GM026020 / NIGMS NIH HHS R01 GM026020 / NIGMS NIH HHS R01 CA075954 / NCI NIH HHS CA75954 / NCI NIH HHS
Language: English
Date published: 06/29/2007
Academic Unit: Biochemistry and Molecular Biology; Internal Medicine
Record Identifier: 9983788428502771

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