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Stringent control and growth-rate-dependent control have nonidentical promoter sequence requirements
C A Josaitis1, T Gaal, R L Gourse
1Department of Bacteriology, University of Wisconsin, Madison 53706.
Summary
Escherichia coli stringent control of rRNA transcription does not require the UP element or FIS protein. Two distinct promoter regions, the discriminator and the consensus promoter, are crucial for stringent control.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Escherichia coli employs stringent control and growth-rate-dependent control for rRNA output regulation.
- Stringent control responds to amino acid availability, while growth-rate control adapts to steady-state growth rates.
Purpose of the Study:
- To investigate the roles of the UP element and FIS protein in stringent control of rRNA transcription.
- To elucidate the relationship and distinct mechanisms between growth-rate-dependent control and stringent control.
Main Methods:
- Examined transcription from rrnB P1 promoters with and without UP element and FIS binding sites after amino acid starvation.
- Measured transcription from growth-rate-independent promoters during amino acid starvation to differentiate regulatory systems.
Main Results:
- The core promoter, lacking UP element and FIS, responded to amino acid starvation, indicating they are not essential for stringent control.
- Growth-rate-independent promoters (mutants and native P2, pS10) exhibited stringent regulation, confirming distinct promoter determinants for each system.
- Specific mutations in the discriminator region and a promoter resembling the E. coli sigma 70 consensus disrupted stringent control of rrnB P1.
Conclusions:
- Stringent control and growth-rate-dependent control utilize different promoter elements and function via distinct mechanisms.
- The discriminator region and promoter consensus sequence are critical for stringent control of rRNA transcription in E. coli.