Two promoters from the Streptomyces plasmid pIJ101 and their expression in Escherichia coli.

An RNA polymerase-binding restriction fragment from the small, high-copy-number Streptomyces plasmid pIJ101 has been shown to have promoter activity in vivo using a promoter-probe vector. The nucleotide sequence of the promoter (the pIJ101B promoter) and the approximate position of the transcription start point as identified by in vitro run-off transcription are presented. Both the pIJ101B promoter and the previously characterised pIJ101A promoter were found to promote transcription in Escherichia coli. The transcription start point in E. coli for the pIJ101A promoter has been determined using high-resolution S1 mapping. Initiation occurs at the same point or within 1 or 2 nucleotides of the transcription start point previously identified in Streptomyces lividans, indicating that the same transcriptional signals are recognised in both genera. The data support the idea that one type of RNA polymerase holoenzyme in Streptomyces recognises a class of promoters similar to the major consensus promoters of E. coli, and that the manner of promoter recognition is similar in both genera.