Synthesis of value-added uridine 5'-diphosphate-glucose from sucrose applying an engineered sucrose synthase counteracts the activity-stability trade-off.

The one-step deconstruction of sucrose into uridine 5'-diphosphate-glucose (UDP-Glc), an important sugar donor for transglycosylation, employing sucrose synthase (Susy) is emerging as a valuable sucrose utilization process. The insufficient activity and stability of Susy limit the productivity of UDP-Glc from sucrose. Here, an engineered Susy (Susy _M6 ) that counteracted the activity-stability trade-off was developed with the half-life time and activity being 43-fold and 1.4-fold of wild-type, respectively. Tighter hydrophobic patches and stabilization of the SSN2 domain contributed to greater activity and stability. The use of Susy _M6 in UDP-Glc production resulted in a satisfactory space-time yield of 73 g/L/h within 1 h. The cascade of different biocatalysts with Susy _M6 , focusing on utilizing two products of sucrose decomposition, fructose and UDP-Glc, expanded sucrose utilization, efficiently promoting the UDP-Glc productivity and giving a cost-effective method for UDP-galactose (UDP-Gal) synthesis. This study demonstrated promising green pathways for producing multiple value-added products from sucrose using Susy.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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