Two genes in Streptomyces alboniger puromycin biosynthesis pathway are closely linked

Several recombinant plasmids, derived from the Streptomyces vector pIJ702 and carrying different stretches of Streptomyces alboniger DNA encoding the gene (pac) for puromycin N-acetyl transferase [Vara et al., Gene 33 (1985) 197-206] were found to also include the gene (dmpM) for the O-demethylpuromycin O-methyl transferase enzyme. Both genes are present on the same 2.4-kb DNA fragment. Coupled transcription-translation experiments suggested that the dmpM gene product is a 44-kDa polypeptide and that both dmpM and pac might belong to different transcriptional units. The level of expression of the dmpM gene was dependent upon the orientation of insertion in the vector.