Highly efficient synthesis of ethyl (S)-4-chloro-3-hydroxybutanoate and its derivatives by a robust NADH-dependent reductase from E. coli CCZU-K14.

An NADH-dependent reductase (CmCR) from Candida magnoliae was discovered by genome mining for carbonyl reductases. After CmCR was overexpressed in Escherichia coli BL21, a robust reductase-producing strain, recombinant E. coli CCZU-K14, was employed for the efficient synthesis of ethyl (S)-4-chloro-3-hydroxybutanoate ((S)-CHBE) from the reduction of ethyl 4-chloro-3-oxobutanoate (COBE). After the optimization, the optimum reaction conditions were obtained. Notably, E. coli CCZU-K14 had broad substrate specificity in reducing both aliphatic and aromatic substrates, and excellent enantioselectivity of CCZU-K14 was observed for most of the tested substrates, resulting in chiral alcohols of over 99.9% ee. Moreover, COBE at a high concentration of (3000mM) could be asymmetrically reduced to (S)-CHBE in the high yield (>99.0%) and high enantiometric excess value (>99.9% ee) after 14h. Significantly, E. coli CCZU-K14 shows high potential in the industrial production of (S)-CHBE and its derivatives (>99.9% ee).