Analysis of cis-Acting Elements Required for bfpA Expression in Enteropathogenic Escherichia coli

bfpA expression in enteropathogenic Escherichia coli is regulated by growth medium, temperature, and ammonium concentration and requires the BfpT protein (also called PerA), a member of the AraC family of transcriptional activators. Site-directed and PCR random mutagenesis, as well as deletion analysis of the bfpA upstream regulatory region, supported assignment of the promoter elements and demonstrated that the cis-acting elements that mediate BfpT-dependent regulation of bfpA are located between positions −85 and −46. Interestingly, this region shares 73% identity with a 40-bp-long AT-rich tract located upstream of the bfpT gene, which is essential for bfpT autoregulation.