KEGG   ENZYME: 2.7.7.69
Entry
EC 2.7.7.69                 Enzyme                                 

Name
GDP-L-galactose/GDP-D-glucose: hexose 1-phosphate guanylyltransferase;
VTC2;
VTC5;
GDP-L-galactose phosphorylase
Class
Transferases;
Transferring phosphorus-containing groups;
Nucleotidyltransferases
Sysname
GDP-beta-L-galactose/GDP-alpha-D-glucose:hexose 1-phosphate guanylyltransferase
Reaction(IUBMB)
(1) GDP-beta-L-galactose + alpha-D-mannose 1-phosphate = beta-L-galactose 1-phosphate + GDP-alpha-D-mannose [RN:R07678];
(2) GDP-alpha-D-glucose + alpha-D-mannose 1-phosphate = alpha-D-glucose 1-phosphate + GDP-alpha-D-mannose [RN:R12607]
Reaction(KEGG)
R07678 R12607
Substrate
GDP-beta-L-galactose [CPD:C02280];
alpha-D-mannose 1-phosphate [CPD:C00636];
GDP-alpha-D-glucose [CPD:C00394]
Product
beta-L-galactose 1-phosphate [CPD:C15926];
GDP-alpha-D-mannose [CPD:C00096];
alpha-D-glucose 1-phosphate [CPD:C00103]
Comment
This plant enzyme catalyses the conversion of GDP-beta-L-galactose and GDP-alpha-D-glucose to beta-L-galactose 1-phosphate and alpha-D-glucose 1-phosphate, respectively. The enzyme can use inorganic phosphate as the co-substrate, but several hexose 1-phosphates, including alpha-D-mannose 1-phosphate, alpha-D-glucose 1-phosphate, and alpha-D-galactose 1-phosphate, are better guanylyl acceptors. The enzyme's activity on GDP-beta-L-galactose is crucial for the biosynthesis of L-ascorbate.
History
EC 2.7.7.69 created 2010, modified 2020
Pathway
ec00053  Ascorbate and aldarate metabolism
ec01100  Metabolic pathways
ec01110  Biosynthesis of secondary metabolites
Orthology
K14190  GDP-L-galactose phosphorylase
Genes
ATH: AT4G26850(VTC2) AT5G55120(VTC5)
ALY: 9300451 9303610
CRB: 17875360 17878615
CSAT: 104717545 104722245 104726045 104730704 104731426 104761532
EUS: EUTSA_v10013622mg EUTSA_v10025206mg
BRP: 103834830 103851903 103861660 103866673(VTC2)
BNA: 106361354 106418494 106420809 106421390 106429510 106444877 106445470
BOE: 106308684 106312359 106327758
RSZ: 108808645 108842402 108853717
THJ: 104811624 104813430
CPAP: 110820751
LJA: Lj0g3v0129419.1(Lj0g3v0129419.1) Lj0g3v0268149.1(Lj0g3v0268149.1)
CSV: 101205337
CMO: 103490128
SLY: 101055572(GGP) 101255942(SlGGP-LIKE)
DOSA: Os12t0190000-01(Os12g0190000) Os12t0612100-01(Os12g0612100)
ZMA: 100272546(si946084h12) 100283852
MNG: MNEG_9746
APRO: F751_3621
 » show all
Reference
1  [PMID:17462988]
  Authors
Linster CL, Gomez TA, Christensen KC, Adler LN, Young BD, Brenner C, Clarke SG.
  Title
Arabidopsis VTC2 Encodes a GDP-L-Galactose Phosphorylase, the Last Unknown Enzyme in the Smirnoff-Wheeler Pathway to Ascorbic Acid in Plants.
  Journal
J Biol Chem 282:18879-85 (2007)
DOI:10.1074/jbc.M702094200
  Sequence
[ath:AT4G26850]
Reference
2  [PMID:17877701]
  Authors
Dowdle J, Ishikawa T, Gatzek S, Rolinski S, Smirnoff N
  Title
Two genes in Arabidopsis thaliana encoding GDP-L-galactose phosphorylase are required for ascorbate biosynthesis and seedling viability.
  Journal
Plant J 52:673-89 (2007)
DOI:10.1111/j.1365-313X.2007.03266.x
  Sequence
Reference
3  [PMID:17950389]
  Authors
Wolucka BA, Van Montagu M.
  Title
The VTC2 cycle and the de novo biosynthesis pathways for vitamin C in plants: an opinion.
  Journal
Phytochemistry 68:2602-13 (2007)
DOI:10.1016/j.phytochem.2007.08.034
Reference
4  [PMID:17485667]
  Authors
Laing WA, Wright MA, Cooney J, Bulley SM.
  Title
The missing step of the L-galactose pathway of ascorbate biosynthesis in plants, an L-galactose guanyltransferase, increases leaf ascorbate content.
  Journal
Proc Natl Acad Sci U S A 104:9534-9 (2007)
DOI:10.1073/pnas.0701625104
Reference
5  [PMID:18463094]
  Authors
Linster CL, Adler LN, Webb K, Christensen KC, Brenner C, Clarke SG
  Title
A second GDP-L-galactose phosphorylase in arabidopsis en route to vitamin C. Covalent intermediate and substrate requirements for the conserved reaction.
  Journal
J Biol Chem 283:18483-92 (2008)
DOI:10.1074/jbc.M802594200
  Sequence
Reference
6  [PMID:18516687]
  Authors
Muller-Moule P
  Title
An expression analysis of the ascorbate biosynthesis enzyme VTC2.
  Journal
Plant Mol Biol 68:31-41 (2008)
DOI:10.1007/s11103-008-9350-4
  Sequence
[ath:AT4G26850]
Other DBs
ExplorEnz - The Enzyme Database: 2.7.7.69
IUBMB Enzyme Nomenclature: 2.7.7.69
ExPASy - ENZYME nomenclature database: 2.7.7.69
BRENDA, the Enzyme Database: 2.7.7.69
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