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The Mechanism of Regulation of Bacteriophage λ pR Promoter Activity by Escherichia coli DnaA Protein
- Source :
- Journal of Biological Chemistry. 278:22250-22256
- Publication Year :
- 2003
- Publisher :
- Elsevier BV, 2003.
-
Abstract
- Apart from its function as an initiator of DNA replication, the Escherichia coli DnaA protein is also a specific transcription factor. It activates and represses a number of promoters. However, mechanisms of transcription stimulation by DnaA remained unknown. Bacteriophage lambda pR promoter is one of the promoters activated by DnaA. It was reported previously that DnaA binds downstream of the pR promoter and perhaps interacts with the RNA polymerase beta subunit. Here we demonstrate that DnaA positively regulates transcription from pR by stimulation of two steps in transcription initiation: RNA polymerase binding to the promoter region and promoter escape. For this transcription activation, two weak DnaA boxes located downstream of pR are necessary and sufficient. Such a mechanism of transcription activation and location of the activator-binding sites relative to the transcription start point are unusual in prokaryotes. Changes in the distance between the transcription start point and the first DnaA box by 5 and 10 bp and alterations in the orientation of these boxes did not abolish the stimulation of transcription by DnaA, but the efficiency of the promoter activation was different for various mutations. It seems plausible that formation of higher order nucleoprotein structures, involving DNA looping, is necessary for effective stimulation of the pR promoter. At high concentrations, DnaA is a repressor of pR rather than an activator. This repression was found to be because of inhibition of RNA polymerase binding to the promoter region.
- Subjects :
- DNA Replication
Gene Expression Regulation, Viral
genetic processes
Response element
Repressor
Biology
Biochemistry
chemistry.chemical_compound
Bacterial Proteins
Transcription (biology)
RNA polymerase
Consensus Sequence
Escherichia coli
Promoter Regions, Genetic
Molecular Biology
Transcription factor
DNA Primers
Base Sequence
General transcription factor
Escherichia coli Proteins
Promoter
DNA-Directed RNA Polymerases
Cell Biology
Bacteriophage lambda
Molecular biology
DnaA
DNA-Binding Proteins
chemistry
health occupations
bacteria
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 278
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....84197fc9cc8a863131d21ec9273b90cf