Characterization of UDP-glucose pyrophosphorylases from different organisms.

UDP-glucose pyrophosphorylases (UGPases) catalyze the conversion of UTP and glucose-1-phosphate (Glc1P) to UDP-glucose and pyrophosphate, playing crucial roles in cell metabolism. The UGPases are related to the biosynthesis of glycans in various organisms and linked to bacterial survival, plant programmed cell death, and even human cancers. Eleven UGPases from the bacterium Escherichia coli; fungi Saccharomyces cerevisiae (ScUGP) and Aspergillus niger (AnUGP); plants Hordeum vulgare (barley) (HvUGP), Arabidopsis thaliana (AtUGP), Solanum tuberosum (potato) (StUGP), Manihot esculenta (cassava) (MeUGP), Ipomoea batatas (sweet potato) (IbUGP), and Zea mays (maize) (ZmUGP); and animals Drosophila melanogaster (fruit fly) (DmUGP) and Homo sapiens (human) (HsUGP) were expressed in E. coli and assayed. MeUGP and StUGP have the highest and second-highest specific activities, respectively. The second-order rate constant kcat/KM values of 11 UGPases are ranked from high to low in the following order: MeUGP > StUGP > ZmUGP > IbUGP > AtUGP > AnUGP > HvUGP > HsUGP > DmUGP > ScUGP > EcUGP. EcUGP, ScUGP, AnUGP, HvUGP, AtUGP, DmUGP, and HsUGP show a temperature optimum of 37℃. MeUGP, IbUGP, and ZmUGP showed a temperature optimum of 50℃. Overall, recombinant UGPases were not thermally stable. Ten UGPases were rapidly inactivated at 60℃ except for IbUGP. The recombinant UGPases use Glc1P with high activities. UGPases exhibit variations in NTP utilization efficiency. The results improve the knowledge of the characteristics of UGPase from various organisms and provide the potential to use MeUGP or StUGP as the engineering target of cell factories.