Abstract
UDP-Arabinopyranose mutase (UAM) catalyzes the interconversion of UDP-arabinofuranose (UDP-Araf) and UDP-arabinopyranose (UDP-Arap). UAM and reversibly glycosylated polypeptides (RGP) are the same protein, so that UAM is related to the differentiation of a cell and generation like RGP. Genome project revealed that UAMs are widespread in green plants which are rice, Arabidopsis, moss, and algae. Rice, Arabidopsis, and chlamydomonas have 3, 5, and 1 UAM homolog, respectively. The function of UAM in algae has been unknown. Here, we cloned UAM from chlamydomonas and prepared a recombinant UAM.
As the result of the characterization of recombinant UAM, the enzyme showed the both activity to form UDP-Araf and UDP-Arap. The optimum activity of UAM was at 60 oC and pH 6.0. Molecular weight of UAM was ≤ 720 kDa, indicating that chlamydomonas UAM forms multi homo complex. When the UAM was incubated in the presence of UDP-[14C]glucose, the enzyme showed the RGP activity.
