The pur6 gene of the puromycin biosynthetic gene cluster from Streptomyces alboniger encodes a tyrosinyl-aminonucleoside synthetase

The pur6 gene of the puromycin biosynthetic gene ( pur) cluster from Streptomyces alboniger is shown to be essential for puromycin biosynthesis. Cell lysates from this mycelial bacterium were active in linking l-tyrosine to both 3 ′-amino-3 ′-deoxyadenosine and N 6, N 6-dimethyl-3 ′-amino-3 ′-deoxyadenosine with a peptide-like bond. Identical reactions were performed by cell lysates from Streptomyces lividans or Escherichia coli transformants that expressed pur6 from a variety of plasmid constructs. Physicochemical and biochemical analyses suggested that their products were tridemethyl puromycin and O-demethylpuromycin, respectively. Therefore, it appears that Pur6 is the tyrosinyl-aminonucleoside synthetase of the puromycin biosynthetic pathway.