Editor: Grzegorz Wegrzyn
Transcriptional switching in Escherichia coli during stress and starvation by modulation of σ70 activity
Article first published online: 30 MAR 2010
© 2010 AstraZeneca India Pvt Ltd. Journal compilation © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd
FEMS Microbiology Reviews
Special Issue: Global control
Volume 34, Issue 5, pages 646–657, September 2010
How to Cite
Sharma, U. K. and Chatterji, D. (2010), Transcriptional switching in Escherichia coli during stress and starvation by modulation of σ70 activity. FEMS Microbiology Reviews, 34: 646–657. doi: 10.1111/j.1574-6976.2010.00223.x
- Issue published online: 2 AUG 2010
- Article first published online: 30 MAR 2010
- Received 13 October 2009; revised 12 February 2010; accepted 12 February 2010.Final version published online 18 May 2010.
- transcription regulation;
- sigma factors;
- 6S RNA
During active growth of Escherichia coli, majority of the transcriptional activity is carried out by the housekeeping sigma factor (σ70), whose association with core RNAP is generally favoured because of its higher intracellular level and higher affinity to core RNAP. In order to facilitate transcription by alternative sigma factors during nutrient starvation, the bacterial cell uses multiple strategies by which the transcriptional ability of σ70 is diminished in a reversible manner. The facilitators of shifting the balance in favour of alternative sigma factors happen to be as diverse as a small molecule (p)ppGpp (represents ppGpp or pppGpp), proteins (DksA, Rsd) and a species of RNA (6S RNA). Although 6S RNA and (p)ppGpp were known in literature for a long time, their role in transcriptional switching has been understood only in recent years. With the elucidation of function of DksA, a new dimension has been added to the phenomenon of stringent response. As the final outcome of actions of (p)ppGpp, DksA, 6S RNA and Rsd is similar, there is a need to analyse these mechanisms in a collective manner. We review the recent trends in understanding the regulation of σ70 by (p)ppGpp, DksA, Rsd and 6S RNA and present a case for evolving a unified model of RNAP redistribution during starvation by modulation of σ70 activity in E. coli.