Present address: DNA Editing Laboratory, Clare Hall Laboratories, Cancer Research UK, South Mimms EN6 3LD, UK.
σ54-RNA polymerase controls σ70-dependent transcription from a non-overlapping divergent promoter
Article first published online: 10 SEP 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
Volume 70, Issue 3, pages 709–723, November 2008
How to Cite
Johansson, L. U. M., Solera, D., Bernardo, L. M. D., Moscoso, J. A. and Shingler, V. (2008), σ54-RNA polymerase controls σ70-dependent transcription from a non-overlapping divergent promoter. Molecular Microbiology, 70: 709–723. doi: 10.1111/j.1365-2958.2008.06440.x
- Issue published online: 3 OCT 2008
- Article first published online: 10 SEP 2008
- Accepted 31 August, 2008.
Divergent transcription of a regulatory gene and a cognate promoter under its control is a common theme in bacterial regulatory circuits. This genetic organization is found for the dmpR gene that encodes the substrate-responsive specific regulator of the σ54-dependent Po promoter, which controls (methyl)phenol catabolism. Here we identify the Pr promoter of dmpR as a σ70-dependent promoter that is regulated by a novel mechanism in which σ54-RNA polymerase occupancy of the non-overlapping σ54-Po promoter stimulates σ70-Pr output. In addition, we show that DmpR stimulates its own production through Po activity both in vivo and in vitro. Hence, the demonstrated regulatory circuit reveals a novel role for σ54-RNA polymerase, namely regulation of a σ70-dependent promoter, and a new mechanism that places a single promoter under dual control of two alternative forms of RNA polymerase. We present a model in which guanosine tetra-phosphate plays a major role in the interplay between σ54- and σ70-dependent transcription to ensure metabolic integration to couple σ70-Pr output to both low-energy conditions and the presence of substrate.