Abstract
Nucleotide sugars are generated from monosaccharide 1-phosphates and nucleotides in the salvage pathway in higher plants. The salvage system of L-fucose is completely independent from that of glucose, galactose, xylose, L-arabinose, and glucuronic acid, which are activated as UDP-sugars. Using genomic database of Arabidopsis and rice, we identified a novel gene, designated AtFKGP (Arabidopsis thaliana L-FucoKinase/GDP-L-fucose Pyrophosphorylase), with similarity to both L-fucokinase and GDP-L-fucose pyrophosphorylase genes. The recombinant AtFKGP expressed in Escherichia coli catalyzed formation of GDP-L-fucose in the presence of ATP, GTP, and L-fucose 1-phosphate. Relatively high expression of AtFKGP was detected in flower buds of Arabidopsis. Loss-of-function mutants with T-DNA insertion in AtFKGP showed accumulation of free L-fucose in the cytoplasmic fraction. These results indicate that AtFKGP catalyzes both conversion of L-fucose 1-phosphote from fucose and ATP, and GDP-L-fucose from L-fucose 1-phosphote and GTP, suggesting that AtFKGP acts for the salvage reaction of L-fucose in Arabidopsis.