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The anti-initial transcribed sequence, a portable sequence that impedes promoter escape, requires sigma70 for
1Department of Stomatology, University of California, San Francisco, 94143, USA.
The Journal of Biological Chemistry
|August 2, 2001
Summary
The anti-sequence prevents promoter escape in sigma70 promoters but not sigma32 promoters. Mutations disrupting sigma70 interactions also abolish anti-sequence function, suggesting a conserved recognition mechanism.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The anti-sequence is a portable DNA element that inhibits promoter escape.
- Sigma70 promoters are essential for transcription initiation in many bacteria.
- Sigma32 is a stress-responsive sigma factor with distinct promoter recognition properties.
Purpose of the Study:
- To investigate the mechanism of anti-sequence function.
- To determine if the anti-sequence functions with sigma32 promoters.
- To identify the role of sigma70-RNA polymerase interactions in anti-sequence activity.
Main Methods:
- Site-directed mutagenesis of sigma70 and RNA polymerase.
- In vitro transcription assays using various promoters.
- Analysis of promoter escape and pausing dynamics.
Main Results:
- The anti-sequence effectively prevents promoter escape from sigma70 promoters but not sigma32 promoters.
- Mutations in sigma70 Region 2.2 that disrupt RNA polymerase interaction abolish anti-sequence function.
- These mutations also impair lambdaQ-mediated anti-termination, suggesting a shared mechanism involving sigma70 and transcribed sequences.
Conclusions:
- Anti-sequence function relies on specific interactions between sigma70 and the non-template strand of the anti-initial transcribed sequence (anti-ITS).
- This mechanism is distinct from sigma32-dependent transcription.
- The findings reveal a conserved molecular basis for promoter escape regulation involving sigma70-DNA interactions.
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