Partial purification and identification of GDP-mannose 3",5"-epimerase of Arabidopsis thaliana, a key enzyme of the plant vitamin C pathway
AUTOR(ES)
Wolucka, Beata A.
FONTE
The National Academy of Sciences
RESUMO
The first step in the biosynthetic pathway of vitamin C in plants is the formation, at the level of sugar nucleotide, of l-galactosyl residues, catalyzed by a largely unknown GDP-d-mannose 3",5"-epimerase. By using combined conventional biochemical and mass spectrometry methods, we obtained a highly purified preparation of GDP-d-mannose 3",5"-epimerase from an Arabidopsis thaliana cell suspension. The native enzyme is an 84-kDa dimer, composed of two apparently identical subunits. In-gel tryptic digestion of the enzyme subunit, followed by peptide sequencing and a blast search, led to the identification of the epimerase gene. The closest homolog of the plant epimerase is the BlmG gene product of Streptomyces sp., a putative NDP-d-mannose 5"-epimerase. The plant GDP-d-mannose 3",5"-epimerase is, to our knowledge, a novel member of the extended short-chain dehydrogenase/reductase family. The enzyme was cloned and expressed in Escherichia coli cells.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=64946Documentos Relacionados
- Genetic evidence for the role of GDP-mannose in plant ascorbic acid (vitamin C) biosynthesis
- Identification and Characterization of GONST1, a Golgi-Localized GDP-Mannose Transporter in Arabidopsis
- Transfer of mannose from GDP-mannose to lipid-linked oligosaccharide by soluble mannosyl transferase.
- Characterization of the gene coding for GDP-mannose dehydrogenase (algD) from Azotobacter vinelandii.
- Molecular and Phenotypic Analysis of CaVRG4, Encoding an Essential Golgi Apparatus GDP-Mannose Transporter