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PMID:10216857

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Citation

Zhi, J, Mathew, E and Freundlich, M (1999) Lrp binds to two regions in the dadAX promoter region of Escherichia coli to repress and activate transcription directly. Mol. Microbiol. 32:29-40

Abstract

The dadAX operon is expressed by multiple promoters that are repressed by leucine-responsive regulatory protein (Lrp) and activated by cyclic AMP-CRP. In previous work, we found that alanine or leucine acted as inducers to antagonize Lrp repression of the three major promoters directly. Here, we identify 11 Lrp binding sites located within 350 bp of dad DNA. A mutational analysis, coupled with in vivo and in vitro transcription experiments, indicated that Lrp sites that overlap the dad promoters were involved in repression. In contrast, sites upstream of the promoters did not appear to be necessary for repression, but were required for activation by Lrp plus alanine or leucine of one of the major dad promoters, P2. This activation by alanine or leucine was not simply relief of repression, as P2 transcription from a constitutive template was increased fivefold compared with the basal level of transcription found in the absence of Lrp and the co-activator cyclic AMP-CRP. Alanine or leucine decreased the affinity of Lrp to repressor sites, while having little or no effect on the binding of Lrp to activator sites. This differential effect of alanine and leucine on Lrp binding helps to explain how these modifiers influence both repression and activation of the dad operon.

Links

PubMed

Keywords

Alanine/pharmacology; Base Sequence; DNA Footprinting; DNA Primers; DNA-Binding Proteins/genetics; Dose-Response Relationship, Drug; Escherichia coli/genetics; Escherichia coli Proteins; Genes, Regulator/genetics; Leucine-Responsive Regulatory Protein; Molecular Sequence Data; Mutagenesis, Site-Directed; Promoter Regions, Genetic; RNA/metabolism; Transcription Factors; Transcription, Genetic; Transcriptional Activation; beta-Galactosidase/metabolism

Significance

Annotations

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

ECOLI:LRP

enables

GO:0001216: DNA-binding transcription activator activity

ECO:0005643: hydroxyl-radical footprinting evidence used in manual assertion

RefSeq:NC_000913.2

F

Seeded From UniProt

complete

ECOLI:LRP

enables

GO:0000976: transcription regulatory region sequence-specific DNA binding

ECO:0005643: hydroxyl-radical footprinting evidence used in manual assertion

RefSeq:NC_000913.2

F

Seeded From UniProt

complete

ECOLI:LRP

enables

GO:0000976: transcription regulatory region sequence-specific DNA binding

ECO:0005667: site-directed mutagenesis phenotypic evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:LRP

enables

GO:0001216: DNA-binding transcription activator activity

ECO:0005667: site-directed mutagenesis phenotypic evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:LRP

enables

GO:0001217: DNA-binding transcription repressor activity

ECO:0005643: hydroxyl-radical footprinting evidence used in manual assertion

RefSeq:NC_000913.2

F

Seeded From UniProt

complete

ECOLI:LRP

enables

GO:0001217: DNA-binding transcription repressor activity

ECO:0005667: site-directed mutagenesis phenotypic evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:LRP

part_of

GO:0032993: protein-DNA complex

ECO:0005667: site-directed mutagenesis phenotypic evidence used in manual assertion

C

Seeded From UniProt

complete

ECOLI:LRP

part_of

GO:0032993: protein-DNA complex

ECO:0005643: hydroxyl-radical footprinting evidence used in manual assertion

RefSeq:NC_000913.2

C

Seeded From UniProt

complete

Notes

See also

References

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