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Sequences in sigmaN determining holoenzyme formation and properties.
- Source :
-
Journal of molecular biology [J Mol Biol] 1999 May 14; Vol. 288 (4), pp. 539-53. - Publication Year :
- 1999
-
Abstract
- Sigma subunits of bacterial RNA polymerases are closely involved in many steps of promoter-specific transcription initiation. Holoenzyme formed with the specialised minor sigma-N (sigmaN) protein binds rare promoters in a transcriptionally inactive state and functions in enhancer-dependent transcription. Using competition and dissociation assays, we show that sigmaN-holoenzyme has a stability comparable to the major sigma70-holoenzyme. Purified partial sequences of sigmaN were prepared and assayed for retention of core RNA polymerase binding activity. Two discrete fragments of sigmaN which both bind the core but with significantly different affinities were identified, demonstrating that the sigmaN interface with core RNA polymerase is extensive. The low affinity segment of sigmaN included region I sequences, an amino terminal domain which mediates activator responsiveness and formation of open promoter complexes. The higher affinity site lies within a 95 residue fragment of region III. We propose that the core to region I contact mediates properties of the sigmaN-holoenzyme important for enhancer responsiveness. Heparin is shown to dissociate sigmaN and core, indicating that disruption of the holoenzyme is involved in the heparin sensitivity of the sigmaN closed complex.<br /> (Copyright 1999 Academic Press.)
- Subjects :
- Amino Acid Sequence
Binding, Competitive
DNA-Directed RNA Polymerases chemistry
Holoenzymes chemistry
Klebsiella pneumoniae metabolism
Molecular Sequence Data
RNA Polymerase Sigma 54
Sigma Factor chemistry
DNA-Binding Proteins
DNA-Directed RNA Polymerases metabolism
Holoenzymes metabolism
Sigma Factor metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0022-2836
- Volume :
- 288
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 10329161
- Full Text :
- https://doi.org/10.1006/jmbi.1999.2704