Nitrile-synthesizing enzyme: Gene cloning, overexpression and application for the production of useful compounds.

One of the nitrile-synthesizing enzymes, β-cyano-L-alanine synthase, catalyzes β-cyano-L-alanine (β-CNAla) from potassium cyanide and O-acetyl-L-serine or L-cysteine. We have identified this enzyme from Pseudomonas ovalis No. 111. In this study, we cloned the β-CNAla synthase gene and expressed it in Escherichia coli and Rhodococcus rhodochrous. Furthermore, we carried out co-expression of β-CNAla synthase with nitrilase or nitrile hydratases in order to synthesize aspartic acid and asparagine from KCN and O-acetyl-L-serine. This strategy can be used for the synthesis of labeled amino acids by using a carbon-labeled KCN as a substrate, resulting in an application for positron emission tomography.