UDP-sugar pyrophosphorylase with broad substrate specificity toward various monosaccharide 1-phosphates from pea sprouts

J Biol Chem. 2004 Oct 29;279(44):45728-36. doi: 10.1074/jbc.M408716200. Epub 2004 Aug 23.


UDP-sugars, activated forms of monosaccharides, are synthesized through de novo and salvage pathways and serve as substrates for the synthesis of polysaccharides, glycolipids, and glycoproteins in higher plants. A UDP-sugar pyrophosphorylase, designated PsUSP, was purified about 1,200-fold from pea (Pisum sativum L.) sprouts by conventional chromatography. The apparent molecular mass of the purified PsUSP was 67,000 Da. The enzyme catalyzed the formation of UDP-Glc, UDP-Gal, UDP-glucuronic acid, UDP-l-arabinose, and UDP-xylose from respective monosaccharide 1-phosphates in the presence of UTP as a co-substrate, indicating that the enzyme has broad substrate specificity toward monosaccharide 1-phosphates. Maximum activity of the enzyme occurred at pH 6.5-7.5, and at 45 degrees C in the presence of 2 mm Mg(2+). The apparent K(m) values for Glc 1-phosphate and l-arabinose 1-phosphate were 0.34 and 0.96 mm, respectively. PsUSP cDNA was cloned by reverse transcriptase-PCR. PsUSP appears to encode a protein with a molecular mass of 66,040 Da (600 amino acids) and possesses a uridine-binding site, which has also been found in a human UDP-N-acetylhexosamine pyrophosphorylase. Phylogenetic analysis revealed that PsUSP can be categorized in a group together with homologues from Arabidopsis and rice, which is distinct from the UDP-Glc and UDP-N-acetylhexosamine pyrophosphorylase groups. Recombinant PsUSP expressed in Escherichia coli catalyzed the formation of UDP-sugars from monosaccharide 1-phosphates and UTP with efficiency similar to that of the native enzyme. These results indicate that the enzyme is a novel type of UDP-sugar pyrophosphorylase, which catalyzes the formation of various UDP-sugars at the end of salvage pathways in higher plants.

MeSH terms

  • Amino Acid Sequence
  • Galactosephosphates / metabolism
  • Glucosephosphates / metabolism
  • Hexosephosphates / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • Nucleotidyltransferases / metabolism*
  • Pisum sativum / enzymology*
  • Substrate Specificity
  • Sugar Phosphates / metabolism
  • UTP-Glucose-1-Phosphate Uridylyltransferase
  • Uridine Diphosphate Sugars / metabolism*


  • Galactosephosphates
  • Glucosephosphates
  • Hexosephosphates
  • Sugar Phosphates
  • Uridine Diphosphate Sugars
  • arabinose-1-phosphate
  • galactose-1-phosphate
  • glucose-1-phosphate
  • Nucleotidyltransferases
  • UDPacetylglucosamine pyrophosphorylase
  • UTP-Glucose-1-Phosphate Uridylyltransferase

Associated data

  • GENBANK/AB178642