Efficient whole-cell biocatalytic synthesis of 2′-deoxy-2′-fluoroadenosine, a key building block for nucleic acid drugs

2′-Deoxy-2′-fluoroadenosine (2′-F-dA) is a nucleoside analogue used as a key building block for oligonucleotide drugs. It can be biosynthesized from a low-cost 2′-deoxy-2′-fluorouridine via one-pot transglycosylation catalyzed by a thymidine phosphorylase (TP) and a purine nucleoside phosphorylase (PNP). However, reliance on purified enzymes and low space-time yields present challenges for industrial application of the process. Here, we develop a whole-cell-based biocatalytic system employing TP and PNP from Escherichia coli , which demonstrates high catalytic efficiency and operational simplicity in scaled-up reaction. In particular, a thermal pretreatment of TP- and PNP-expressing whole cells, determined as 50 °C for 3 h, effectively suppressed endogenous deamination side reaction while enhancing 2′-F-dA yield. Subsequent optimization of enzyme and substrate loadings and their relative ratios achieved an unprecedented space-time yield of 1.22 g/L/h with 88.1 g/L product titer in a 500 mL scaled-up reaction, manifesting a highest total conversion of 68.2 %. An integrated purification process yielded gram-scale solid powder of 2′-F-dA with 98.0 % chemical purity and 85.0 % recovery. This novel whole-cell biocatalytic process demonstrates significant industrial potential for the production of 2′-F-dA.