Transcription from the P1 promoters of Micromonospora echinospora in the absence of native upstream DNA sequences.

We demonstrated previously that the 0.4-kilobase DNA fragment from Micromonospora echinospora contains multiple tandem promoters, P1a, P1b, P1c, and P2, which are also functional when cloned into Streptomyces lividans. We now show by in vitro transcription with Streptomyces RNA polymerase that each of these promoters is an authentic initiation site, rather than a processing site for transcripts which initiate further upstream. The DNA sequence requirements for the closely spaced promoters P1a, P1b, and P1c, which are coordinately induced during stationary phase in M. echinospora, were examined by deletional analysis in S. lividans. The P1a and P1b promoters were functional despite deletion of native sequences 5 and 17 base pairs upstream of each initiation site, respectively. Thus, P1a and P1b had greatly reduced upstream DNA sequence requirements compared with typical procaryotic promoters. In contrast, transcription from promoter P1c was significantly decreased when native sequences 34 base pairs upstream were replaced.