Figure 2

A schematic model for the Psp response system in E. coli. A schematic model for the Psp response system in E. coli. Under normal conditions, PspA is bound to PspF, which prevents PspF to initiate the transcriptional response. Under stress conditions, PspA and PspF separate in an PspB, PspC and ArcB dependent manner, which allows PspF to initiate the transcription. The sizes of proton symbols H⁺ around the inner membrane schematically picture the established pmf under normal conditions and dissipated pmf under stress conditions. Under normal conditions the PspA protein plays the role of a negative regulator, while under stress conditions PspA turns into an effector of the Psp response.