Escherichia coli pfs Transcription: Regulation and Proposed Roles in Autoinducer-2 Synthesis and Purine Excretion

Pfs expression is required for several metabolic pathways and limits the production of autoinducer-2, a molecule proposed to play a central role in interspecies quorum sensing. The present study reveals physiological conditions and promoter DNA elements that regulateEscherichia coli pfs transcription. Pfs transcription is shown to rely on both sigma 70 and sigma 38 (rpoS ), and the latter is subject to induction that increasespfs expression. Transcription is maximal as the cells approach stationary phase, and this level can be increased by salt stress through induction of sigma 38-dependent expression. Thepfs promoter is shown to contain both positive and negative elements, which can be used by both forms of RNA polymerase. The negative element is contained within the overlappingdgt promoter, which is involved in purine metabolism. Consideration of the physiological roles of sigma 38 anddgt leads to a model for how autoinducer production is controlled under changing physiological conditions.