Fig. 5: Regulation of Transcription of the σ54 controlled Psp system.
From: The route to transcription initiation determines the mode of transcriptional bursting in E. coli
The Psp system stabilises damaged inner membranes of bacteria23,27. Transcription of Psp is controlled by RNA polymerase/σ54 and requires ATP hydrolysis by the bacterial enhancer binding and activator protein PspF. In absence of membrane stress, the negative regulator PspA (as low-order oligomer) forms an inhibitory complex with PspF in a 6:6 ratio. PspA prevents ATP hydrolysis by PspF and thus Psp transcription. IHF bends the promoter DNA bringing the enhancer-bound PspF in contact with the RNA polymerase/σ54. Membrane stress, e.g., through mislocalisation of proteins such as secretin pIV to the inner membrane enables the release of PspA from PspF. Subsequent ATP hydrolysis by PspF yields open complex formation and initiates Psp transcription. Additional information on the regulation of transcription of the σ54 controlled Psp system can be found in Supplementary Figs. 11, 12.
