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Gene encoding sigma E is transcribed from a sigma A-like promoter in Bacillus subtilis
T J Kenney1, P A Kirchman, C P Moran
1Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322.
Journal of Bacteriology
|July 1, 1988
Summary
Bacillus subtilis sporulation relies on sigma E, transcribed from the spoIIG operon. Researchers identified the spoIIG promoter, revealing a unique structure and suggesting a novel regulatory mechanism for this essential bacterial process.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Genetics
Background:
- Bacillus subtilis utilizes multiple RNA polymerase sigma factors for cellular processes.
- Sigma H and sigma E are crucial for endospore formation, with sigma E produced post-sporulation onset.
- The sigma E encoding gene is located within the spoIIG operon, transcribed during sporulation.
Purpose of the Study:
- To determine the transcription start site and nucleotide sequence of the Bacillus subtilis spoIIG promoter.
- To investigate the interaction of RNA polymerase sigma factors with the spoIIG promoter.
- To elucidate the regulatory mechanism governing spoIIG operon transcription during sporulation.
Main Methods:
- Determination of transcription start site and nucleotide sequencing of the spoIIG promoter.
- In vivo analysis of promoter utilization using single-base substitutions.
- In vitro transcription assays with different Bacillus subtilis RNA polymerase holoenzymes.
Main Results:
- The spoIIG promoter contains -10 and -35 regions similar to E sigma A promoters but with an unusual 22-base pair separation.
- Single-base substitutions in the -10-like region decreased promoter utilization in vivo.
- E sigma A initiated transcription in vitro, while other sigma factors did not, indicating E sigma A transcribes the spoIIG operon.
- A -35 region mutation resulted in constitutive transcription in vegetative cells.
Conclusions:
- The Bacillus subtilis spoIIG promoter is recognized by E sigma A, despite its unique spacing.
- Regulation of spoIIG operon transcription involves a potentially novel mechanism affecting sporulation-specific gene expression.