[Structure analysis of a DNA fragment containing strong promoter activity from Streptomyces mycarofaciens 1748].

A HindIII-HindIII 2.0kb DNA fragment containing promoter activity has been cloned from medicamycin producing strain (S. mycarofaciens 1748), using promoter -probe plasmid vector pIJ486. Transformants of recombinant plasmid p4H2 containing this fragment were resistant to Km in the level above 500 micrograms/ml in MM medium. The result of subcloning deletion analysis indicated that different part of deletion of this fragment would show various extent of effect on the promoter activity. A rather complicated transcriptional regulatory mechanism was suggested. DNA sequence analysis revealed that this fragment consisted of 1984 nucleotides with 47.7% of G+C content. No typical ORF of Streptomyces gene was found. Certain regions showed some homologies with promoters of Streptomyces genes. In 520-570bp region, a sequence similar to the upstream activator sequence (UAS) of E.coli tRNA was discovered. This implied that a possible "enhancer" element was involved in Streptomyces gene transcription.