A bifunctional enzyme with L-fucokinase and GDP-L-fucose pyrophosphorylase activities salvages free L-fucose in Arabidopsis
スポンサーリンク
概要
- 論文の詳細を見る
Monomeric sugars generated during the metabolism of polysaccharides, glycoproteins, and glycolipids are imported to the cytoplasm and converted to respective nucleotide sugars via monosaccharide 1-phosphates, to be reutilized as activated sugars. Because L-fucose (L-Fuc) is activated mainly in the form of GDP derivatives in seed plants, the salvage reactions for L-Fuc are expected to be independent from those for Glc, Gal, L-arabinose, and glucuronic acid, which are activated as UDP-sugars. For this study we have identified, in the genomic data base of Arabidopsis, the gene (designated AtFKGP) of a bifunctional enzyme with similarity to both L-fucokinase and GDP-L-Fuc pyrophosphorylase. Recombinant AtFKGP (rAt-FKGP) expressed in Escherichia coli showed both L-fucokinase and GDP-L-Fuc pyrophosphorylase activities, generating GDP-L-Fuc from L-Fuc, ATP, and GTPas the starting substrates. Point mutations in rAtFKGPs at either Gly(133) or Gly(830) caused loss of GDP-L-Fuc pyrophosphorylase and L-fucokinase activity, respectively. The apparent Km values of L-fucokinase activity of rAtFKGP for L-Fuc and ATP were 1.0 and 0.45mM, respectively, and those of GDP-L-Fuc pyrophosphorylase activity for L-Fuc 1-phosphate and GTP were 0.052 and 0.17mM, respectively. The expression of AtFKGP was detected in most cell types of Arabidopsis, indicating that salvage reactions for free L-Fuc catalyzed by AtFKGP occur ubiquitously in Arabidopsis. Loss-of-function mutants with tDNA insertion in AtFKGP exhibited higher accumulation of free L-Fuc in the soluble fraction than the wild-type plant. These results indicate that AtFKGP is a bifunctional enzyme with L-fucokinase and GDP-L-Fuc pyrophosphorylase activities, which salvages free L-Fuc in Arabidopsis.
論文 | ランダム
- 胃運動機能と胃疾患
- 大学出版部(会)めぐり その7 早稲田大学出版部からの報告--早稲田大学の改革に応えるために
- 高温用ナトリウムヒ-トパイプの開発
- 一様流中におけるロスビ-波
- 抗元感作過程におけるアスコルビン酸の還元グルタチオン誘導効果