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PMID:11742992

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Citation

Wade, JT, Belyaeva, TA, Hyde, EI and Busby, SJ (2001) A simple mechanism for co-dependence on two activators at an Escherichia coli promoter. EMBO J. 20:7160-7

Abstract

The Escherichia coli melAB promoter is co-dependent upon two transcription activators, MelR and the cyclic AMP receptor protein, CRP. In this study we demonstrate positive co-operativity between the binding of MelR and CRP at the melAB promoter, which provides a simple mechanism for its co-dependence. MelR binds to four sites, centred at positions -42.5, -62.5, -100.5 and -120.5 relative to the melAB transcription start point. When MelR is pre-bound, CRP is able to bind to a target located between MelR at positions -62.5 and -100.5. This increases the occupation of the two downstream sites for MelR, which is essential for transcription activation. We have identified residues within activating region 1 (AR1) of CRP that are important in transcription activation of the melAB promoter. At simple CRP-dependent promoters, the surface of CRP containing these residues is involved in contacting the RNA polymerase alpha subunit. Our results show that, at the melAB promoter, the surface of CRP containing AR1 contacts MelR rather than RNA polymerase. Thus, MelR and CRP activate transcription by a novel mechanism in which they bind co-operatively to adjacent sites and form a bacterial enhanceosome.

Links

PubMed PMC125794 Online version:10.1093/emboj/20.24.7160

Keywords

Base Sequence; DNA Footprinting; DNA, Bacterial/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli Proteins; Genes, Bacterial; Models, Molecular; Molecular Sequence Data; Promoter Regions, Genetic; Protein Binding; Protein Conformation; Receptors, Cyclic AMP/chemistry; Receptors, Cyclic AMP/metabolism; Trans-Activators/metabolism; Transcriptional Activation

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ECOLI:MELR

enables

GO:0003677: DNA binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:CRP

acts_upstream_of_or_within

GO:0006351: transcription, DNA-templated

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ECOLI:CRP

involved_in

GO:0006351: transcription, DNA-templated

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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