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Binding of the initiation factor sigma(70) to core RNA polymerase is a multistep process
T M Gruber1, D Markov, M M Sharp
1Departments of Stomatology and Microbiology and Immunology, University of California, San Francisco 94143, USA.
Molecular Cell
|August 21, 2001
Summary
Researchers identified key interaction sites between RNA polymerase and sigma(70) (a bacterial transcription factor). This reveals a multi-step binding process crucial for initiating gene transcription.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Transcription initiation is a fundamental biological process regulated by the interaction between RNA polymerase and initiation factors.
- Sigma(70) is a key initiation factor in Escherichia coli, essential for directing RNA polymerase to promoter sites.
Purpose of the Study:
- To identify specific contact sites between RNA polymerase and the sigma(70) factor.
- To elucidate the dynamic nature of the RNA polymerase-sigma(70) interaction during transcription initiation.
Main Methods:
- Site-directed mutagenesis was employed to verify interaction sites.
- Biochemical assays were used to analyze the interaction between RNA polymerase and sigma(70).
Main Results:
- Nine mutationally verified interaction sites between sigma(70) and RNA polymerase were identified.
- Evidence suggests a multi-step interaction mechanism between sigma(70) and core RNA polymerase.
- The interface between sigma(70) and RNA polymerase undergoes dynamic changes during transcription initiation.
Conclusions:
- The identified interaction sites are critical for the functional association of sigma(70) with RNA polymerase.
- A stepwise binding model is proposed for transcription initiation, involving conformational changes at the interface.
- Understanding these interactions provides insights into the regulation of bacterial gene expression.
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