Reference : Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in ...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants
Linster, Carole mailto [University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB) > >]
Gomez, Tara A. [> >]
Christensen, Kathryn C. [> >]
Adler, Lital N. [> >]
Young, Brian D. [> >]
Brenner, Charles [> >]
Clarke, Steven G. [> >]
Journal of Biological Chemistry
American Society for Biochemistry and Molecular Biology
Yes (verified by ORBilu)
[en] 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.

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