Open AccessTranscriptional switching in Escherichia coli during stress and starvation by modulation of σ 70 activity
Author(s) -
Sharma Umender K.,
Chatterji Dipankar
Publication year - 2010
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.2010.00223.x
Subject(s) - sigma factor , stringent response , biology , transcription (linguistics) , rna , escherichia coli , rna polymerase , transcriptional regulation , microbiology and biotechnology , genetics , transcription factor , gene , linguistics , philosophy
During active growth of Escherichia coli , majority of the transcriptional activity is carried out by the housekeeping sigma factor (σ 70 ), 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 σ 70 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 σ 70 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 σ 70 activity in E. coli .