Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2005
Publication Date: 7/18/2005
Citation: Litterer, L.A., Plaisance, K.L., Schnurr, J.A., Storey, K.K., Gronwald, J.W., Somers, D.A. 2005. Characterization and expression of UDP-sugar pyrophosphorylase from Arabidopsis [abstract]. American Society of Plant Biologists Annual Meeting. Abstract No. 579. Interpretive Summary:
Technical Abstract: A bioinformatics approach was used to clone and characterize a UDP-sugar pyrophosphorylase (AtUSP) from Arabidopsis thaliana that has high activity with UDP-glucuronic acid (UDP-GlcA). AtUSP is predicted to be a cytosolic protein that belongs to a pyrophosphorylase family distantly related to the UDP-glucose and UDP-N-acetylglucosamine pyrophosphorylase families. The recombinant enzyme expressed in E. coli had high activity with GlcA-1-P, glucose-1-P, and galactose-1-P but very low activity with N-acetylglucosamine-1-P, fucose-1-P, mannose-1-P, inositol-1-P, or glucose-6-P. The enzyme had a molecular weight of 70 kDa, was activated by magnesium and preferred UTP as co-substrate. AtUSP had apparent Km values for GlcA-1-P, glucose-1-P, and UTP of 0.13 mM, 0.42 mM, and 0.14 mM, respectively. In the reverse direction, the apparent Km values for UDP-GlcA, UDP-glucose, and pyrophosphate were 0.56 mM, 0.72 mM, and 0.15 mM, respectively. Evaluation of AtUSP expression by semiquantitative RT-PCR and enzyme activity assays indicated that both transcript and enzyme are widely expressed.