EXPRESSION FROM THE CLOSTRIDIUM-PERFRINGENS CPE PROMOTER IN CLOSTRIDIUM-PERFRINGENS AND BACILLUS-SUBTILIS

Clostridium perfringens is a source of food poisoning in humans and an imals because of production of a potent enterotoxin (CPE). To study th e regulation of the cpe gene in C. perfringens, we cloned and sequence d the cpe promoter regions and N-terminal domains from three strains. The cpe promoter region from one strain contained a 45-bp insertion co mpared with previously published sequences. This insertion was also fo und in two (of five) other Cpe(+) strains. cpe gene expression in C. p erfringens was measured by using translational fusions of each promote r type to the Escherichia coli gusA gene, which codes for beta-glucuro nidase. For either promoter type, cpe-gusA expression was undetectable throughout exponential growth but increased dramatically at the begin ning of the stationary phase. To measure cpe expression in Bacillus su btilis, cpe-gusA fusions were integrated into the B. subtilis chromoso me. Both types of promoter exhibited moderate expression during expone ntial growth; cpe expression increased threefold at the beginning of t he stationary phase. Transcriptional start sites were determined by pr imer extension and in vitro transcription assays. For C. perfringens, both types of promoter gave the same 5' end, 197 bp upstream of the tr anslation start (50 bp downstream of the 45-bp insertion). In B. subti lis, however, the 5' end was internal to the 45-bp insertion, suggesti ng the use of a different promoter than that utilized by C. perfringen s.