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Functions of the sigma(54) region I in trans and implications for transcription activation.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 1999 Sep 03; Vol. 274 (36), pp. 25285-90. - Publication Year :
- 1999
-
Abstract
- Control of transcription frequently involves the direct interaction of activators with RNA polymerase. In bacteria, the formation of stable open promoter complexes by the sigma(54) RNA polymerase is critically dependent on sigma(54) amino Region I sequences. Their presence correlates with activator dependence, and removal allows the holoenzyme to engage productively with melted DNA independently of the activator. Using purified Region I sequences and holoenzymes containing full-length or Region I-deleted sigma(54), we have explored the involvement of Region I in transcription activation. Results show that Region I in trans inhibits a reversible conformational change in the holoenzyme believed to be polymerase isomerization. Evidence is presented indicating that the holoenzyme (and not the promoter DNA per se) is one interacting target used by Region I in preventing polymerase isomerization. Activator overcomes this inhibition in a reaction requiring nucleotide hydrolysis. Region I in trans is able to inhibit activated transcription by the holoenzyme containing full-length sigma(54). Inhibition appeared to be noncompetitive with respect to the activator, suggesting that a direct activator interaction occurs with parts of the holoenzyme outside Region I. Stabilization of isomerized holoenzyme bound to melted DNA by Region I in trans occurs largely independently of the initiating nucleotide, suggesting a role for Region I in maintaining the open complex.
- Subjects :
- Bacterial Proteins genetics
Bacterial Proteins metabolism
DNA-Directed RNA Polymerases metabolism
Escherichia coli metabolism
Escherichia coli Proteins
Gene Expression Regulation, Bacterial
RNA Polymerase Sigma 54
Sigma Factor metabolism
Transcriptional Activation
DNA-Binding Proteins
DNA-Directed RNA Polymerases genetics
Escherichia coli genetics
Sigma Factor genetics
Transcription, Genetic
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 274
- Issue :
- 36
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 10464252
- Full Text :
- https://doi.org/10.1074/jbc.274.36.25285