Ploughing a lonely furrow: the curious case of the P1 promoter in the osmotically regulated proU operon of Escherichia coli

Abstract

Evidence is reviewed for the existence of a a-controlled promoter for the osmotically regulated proU operon in Escherichia coli and Salmonella typhimurium. Expression from the promoter is rendered cryptic in both the organisms, most likely by a mechanism of factor- dependent termination of transcription (attenuation) in the region upstream of the structural genes. The possible role of PI in proU expression and regulation is discussed.