e By selective enrichment, we isolated a bacterium that can use -phenylalanine as a sole nitrogen source. It was identified by 16S rRNA gene sequencing as a strain of Variovorax paradoxus. Enzyme assays revealed an aminotransferase activity. Partial genome sequencing and screening of a cosmid DNA library resulted in the identification of a 1,302-bp aminotransferase gene, which encodes a 46,416-Da protein. The gene was cloned and overexpressed in Escherichia coli. The recombinant enzyme was purified and showed a specific activity of 17.5 U mg ؊1 for (S)--phenylalanine at 30°C and 33 U mg ؊1 at the optimum temperature of 55°C. The -specific aminotransferase exhibits a broad substrate range, accepting ortho-, meta-, and para-substituted -phenylalanine derivatives as amino donors and 2-oxoglutarate and pyruvate as amino acceptors. The enzyme is highly enantioselective toward (S)--phenylalanine (enantioselectivity [E], >100) and derivatives thereof with different substituents on the phenyl ring, allowing the kinetic resolution of various racemic -amino acids to yield (R)--amino acids with >95% enantiomeric excess (ee). The crystal structures of the holoenzyme and of the enzyme in complex with the inhibitor 2-aminooxyacetate revealed structural similarity to the -phenylalanine aminotransferase from Mesorhizobium sp. strain LUK. The crystal structure was used to rationalize the stereo-and regioselectivity of V. paradoxus aminotransferase and to define a sequence motif with which new aromatic -amino acid-converting aminotransferases may be identified.