In this research article, we demonstrate direct conversion of glucose to D-tagatose, a low-calorie rare sugar, using an engineered Escherichia coli whole-cell system. Our study identifies a galactose-1-phosphate phosphatase (DdGal1Pase) with stringent substrate selectivity driven by distinct hydrogen-bond networks, enabling reversal of the Leloir pathway and glucose-based tagatose biosynthesis. This work provides a foundation for sustainable production of low-calorie sweetener tagatose.
Highlights:
- Engineered E. coli to convert glucose directly into D-tagatose
- Reversed the Leloir pathway to enable galactose formation directly from glucose
- Identified a phosphatase specific to galactose-1-phosphate
- Computational analyses revealed basis of phosphatase substrate selectivity