Formation of the Nonproteinogenic Amino Acid 2 S ,3 R ‐Capreomycidine by VioD from the Viomycin Biosynthesis Pathway

The tuberactinomycin peptide antibiotics possess several nonproteinogenic amino acids, including the signature capreomycidine residue arising from the oxidative cyclization of the L ‐arginine side chain. The vioD gene from the recently cloned viomycin biosynthesis gene cluster was expressed in E. coli , and the corresponding protein shown to catalyze the pyridoxal phosphate dependent conversion of 3 S ‐hydroxy‐ L ‐arginine to 2 S ,3 R ‐capreomycidine. VioD is the first example of a PLP‐dependent enzyme that promotes an intramolecular β‐replacement reaction.