Analysis of transcriptional control regions in the Streptomyces subtilisin-inhibitor-encoding gene.

A transcript, of about 650 nucleotides (nt), from the Streptomyces subtilisin-inhibitor-encoding gene (ssi) was identified by Northern hybridization analysis in both the original strain, S. albogriseolus S-3253, and the transformant, S. lividans 66, carrying an expression plasmid with the cloned ssi gene, pJS1. These results were quite consistent with the analysis of the major transcriptional start point (tsp; at nt 429) by primer extension experiments and the transcriptional end point (at nt 1065) by S1 nuclease mapping of the ssi gene. Deletion experiments on the 5'-flanking region of the major tsp suggested that two promoter sequences control the expression of ssi. The more proximal of these putative promoters appears to be homologous to the -45 to -25 region of the ctc promoter in Bacillus subtilis and includes a direct repeat in the -10 region.