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SigmaE is an essential sigma factor in Escherichia coli
A De Las Peñas1, L Connolly, C A Gross
1Department of Bacteriology, University of Wisconsin-Madison, 53706, USA.
Journal of Bacteriology
|November 14, 1997
Summary
SigmaE, crucial for the extracytoplasmic stress response in Escherichia coli, is essential at all temperatures. Its apparent nonessentiality at lower temperatures is due to suppressor mutations that rescue growth.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- SigmaE is an alternative sigma factor in Escherichia coli.
- It regulates the extracytoplasmic stress response.
- Previously considered nonessential below 37°C.
Purpose of the Study:
- To investigate the essentiality of SigmaE at all temperatures.
- To understand the mechanism allowing growth in SigmaE-deficient cells at low temperatures.
Main Methods:
- Genetic analysis of Escherichia coli.
- Phenotypic characterization of SigmaE-deficient mutants.
- Identification of suppressor mutations.
Main Results:
- SigmaE is essential for Escherichia coli viability at all temperatures.
- Cells lacking SigmaE can grow at low temperatures.
- This growth is facilitated by unlinked suppressor mutations.
Conclusions:
- SigmaE is a universally essential sigma factor in Escherichia coli.
- Suppressor mutations can mask the essential role of SigmaE at lower temperatures.
- Understanding these suppressors provides insights into cellular stress response.