Efficient Biosynthesis of Ethyl (R)-3-Hydroxyglutarate through a One-Pot Bienzymatic Cascade of Halohydrin Dehalogenase and Nitrilase

An effective one-pot bienzymatic synthesis of ethyl (R)-3-hydroxyglutarate (EHG) from ethyl (S)-4-chloro-3-hydroxybutyrate (ECHB) was achieved by using recombinant Escherichia coli cells expressing separately or co-expressing a mutant halohydrin dehalogenase gene from Agrobacterium radiobacter AD1 and a nitrilase gene from Arabidopsis thaliana. The activity of nitrilase was inhibited by high concentration of ECHB and NaCN. Consequently, the one-pot one-step process was implemented by fed-batch of ECHB and NaCN with high accumulative product concentration (up to 0.9molL(-1)). The biotransformation of ECHB to EHG was successfully achieved at 1.2molL(-1) substrate concentration by a one-pot two-step process. As such, this one-pot bienzymatic transformation should be useful in synthesizing these important optical pure -hydroxycarboxylic acids.