Computer-directed rational design enhanced the thermostability of carbonyl reductase LsCR for the synthesis of ticagrelor precursor

Carbonyl reductases are useful for producing optically active alcohols from their corresponding prochiral ketones. Herein, we applied a computer-assisted strategy to increase the thermostability of a previously constructed carbonyl reductase, LsCR(M4) (N101D/A117G/F147L/E145A), which showed an outstanding activity in the synthesis of the ticagrelor precursor (1S)-2-chloro-1-(3,4-difluorophenyl)ethanol. The stability changes introduced by mutations at the flexible sites were predicted using the computational tools FoldX, I-Mutant 3.0, and DeepDDG, which demonstrated that 12 virtually screened mutants could be thermally stable; 11 of these mutants exhibited increased thermostability. Then a superior mutant LsCR(M4)-V99L/D150F was screened out from the library that was constructed by iteratively combining the beneficial sites, which showed a 78% increase in activity and a 17.4 degrees C increase in melting temperature compared to LsCR(M4). Our computer-assisted design and combinatorial strategy dramatically increased the efficiency of thermostable enzyme production.