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Two domains within sigmaN (sigma54) cooperate for DNA binding
W V Cannon1, M K Chaney, X Wang
1Department of Biology, Imperial College of Science, Technology and Medicine, London, SW7 2BB, United Kingdom.
Summary
The sigma-N (sigmaN) subunit of bacterial RNA polymerase has two domains: one for DNA binding and another that enhances it. This domain communication is crucial for enhancer-dependent transcription activation.
Area of Science:
- Molecular Biology
- Bacterial Transcription
- Protein-DNA Interactions
Background:
- Sigma-N (sigmaN) is a subunit of bacterial RNA polymerase.
- SigmaN-RNA polymerase holoenzyme binds promoters but requires activation for transcription initiation.
Purpose of the Study:
- To investigate the DNA-binding mechanism of the sigma-N subunit.
- To identify distinct functional domains within sigmaN responsible for DNA binding and activity enhancement.
Main Methods:
- Experimental analysis of sigmaN protein domains.
- Assessing DNA-binding activity and enhancement.
- Investigating interactions with core RNA polymerase.
Main Results:
- SigmaN possesses two distinct domains: a C-terminal DNA-binding domain and an adjacent domain enhancing DNA binding.
- Sequences for DNA-binding enhancement are separable from those for core RNA polymerase binding.
- Evidence for inter-domain communication within the sigmaN transcription factor.
Conclusions:
- SigmaN's DNA-binding activity is mediated by two separable domains.
- Inter-domain communication is essential for sigmaN function in enhancer-dependent transcription.
- These findings elucidate mechanisms of transcription factor regulation.