Host: The Japanese Society of Plant Physiologists
Pages 0271
L-Arabinofuranosyl (Araf) residues are an important constituent found in plant cell walls. UDP-L-arabinopyranose (UDP-Arap) is synthesized by several enzymes and then enzymatically converted to UDP-L-Arabinofuranose (UDP-Araf), which is a real sugar donor for Araf-containing cell wall components. We showed that rice seedlings had UDP-Ara interconversion activity and purified the enzyme, UDP-arabinopyranose mutase (UAM), to homogeneity. The reaction is reversible and the formation of UDP-Arap is favored over the formation of UDP-Araf (90:10). Amino acid sequence of the purified UAM revealed that rice has three corresponding genes, UAM1~3, and that these proteins are identical to those previously reported as "reversibly glycosylated polypeptide" (RGP). The recombinant UAMs were obtained using baculovirus/insect cell system and characterized. Recombinant UAM1 and UAM3 had mutase activity with similar enzymatic properties but no activity was observed for UAM2. RGPs are found in the whole plant kingdom, indicating that UAM function is necessary for normal plant growth.
