One-Pot Asymmetric Synthesis of an Aminodiol Intermediate of Florfenicol Using Engineered Transketolase and Transaminase

Florfenicol is the 3′-fluoro derivative of thiamphenicol and has been widely used in veterinary medicine for its high antibacterial activity and safety. However, the development of simplified and environmentally friendly catalytic methods for the stereoselective production of florfenicol is a key challenge. Herein, we established a highly stereoselective enzymatic one-pot reaction for the synthesis of an aminodiol intermediate of florfenicol bearing two stereocenters from industrial raw material 4-(methylsulfonyl) benzaldehyde by coupling transketolase (TK) and ω-transaminase (TA). The enantioselectivity of TK from E. coli was converted from (S) (93% ee) to (R) (95% ee), and we also inverted the enantiopreference (E(S) = 9 to E(R) = 12) and ketone/aldehyde substrate selectivity of TA ATA117 via structure-guided enzyme engineering. Docking calculations and molecular dynamics simulations of the wild-type and mutant enzymes unveiled the molecular basis for enzymatic stereocontrol. Using the engineered TK and TA, (1R,2R)-p-methylsulfonyl phenylserinol was biosynthesized with good yield (76%) and high stereoselectivity (96% de and >99% ee). Our work established an enzymatic synthetic route to (1R,2R)-p-methylsulfonyl phenylserinol, facilitating the development of a chemoenzymatic method for producing florfenicol.