Reshaping UDP-binding pocket of bacterial sucrose synthase to improve efficiency of UDP-glucose production

UDP-glucose (UDPG), a nucleoside diphosphate sugar, is an important sugar donor for the biosynthesis of various glycoside compounds. Sucrose synthase (SuSy) can catalyze the synthesis of high-value UDPG from the cost-effective sucrose. By redesigning the substrate-binding pocket of SuSy in Denitrovibrio acetiphilus DSM 12809, a variant with 8.1-fold increased activity was generated in this study. Structural analysis revealed that the synergistic effect of the newly introduced hydrogen bonds and salt bridges was crucial for the enhanced activity. The yield of UDPG reached 127.6 g/L/h using this variant for catalysis. Moreover, when cascaded with glycosyltransferase for salidroside production, the yield of salidroside increased 2.7-fold, and a UDP recycling number of 3.2 was achieved. These results provide technical support for the industrial application of SuSy in the biosynthesis of nucleotide sugars and glycosides.