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.