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The essential activities of the bacterial sigma factor
Maria C Davis1,1, Christopher A Kesthely1,1, Emily A Franklin1,1
1Department of Biology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada.
Canadian Journal of Microbiology
|January 25, 2017
Summary
Sigma factors are crucial for bacterial transcription initiation. They guide RNA polymerase to DNA and stabilize the open complex, with structural studies revealing nucleotide capture in promoter binding.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Transcription is the initial and most regulated step in gene expression.
- Sigma (σ) factors are essential general transcription factors that bind RNA polymerase (RNAP) to initiate transcription of all bacterial genes.
- σ Factors are critical for targeting RNAP to specific DNA promoters, unwinding the DNA to form an open complex, and interacting with other transcription factors.
Purpose of the Study:
- To review the structure and function of the σ70 family of σ proteins.
- To elucidate the essential roles of σ factors in bacterial transcription.
Main Methods:
- This review synthesizes information from recent structural studies.
- Analysis of the mechanism by which σ factors bind promoter DNA.
- Description of the stabilization of the promoter open-complex intermediate.
Main Results:
- σ Factors target RNAP holoenzyme to specific promoters.
- σ Factors melt double-stranded promoter DNA, stabilizing it as a single-stranded open complex.
- Structural studies show σ factors capture flipped-out nucleotides from promoter DNA, stabilizing the open complex.
Conclusions:
- The σ70 family of σ proteins plays essential roles in bacterial transcription.
- Understanding σ factor structure and function is key to comprehending gene expression regulation.
- Nucleotide capture during promoter binding is a critical mechanism for transcription initiation.
Keywords:
ARN polyméraseRNA polymerasebacteriabactérieexpression géniquefacteur sigmagene expressionsigma factortranscriptionMore Related Videos
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