PMID:9556617
| Citation |
Rhee, KY, Senear, DF and Hatfield, GW (1998) Activation of gene expression by a ligand-induced conformational change of a protein-DNA complex. J. Biol. Chem. 273:11257-66 |
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| Abstract |
IlvY protein binds cooperatively to tandem operator sites in the divergent, overlapping, promoter-regulatory region of the ilvYC operon of Escherichia coli. IlvY positively regulates the expression of the ilvC gene in an inducer-dependent manner and negatively regulates the transcription of its own divergently transcribed structural gene in an inducer-independent manner. Although binding of IlvY protein to the tandem operators is sufficient to repress ilvY promoter-specific transcription, it is not sufficient to activate transcription from the ilvC promoter. Activation of ilvC promoter-specific transcription requires the additional binding of a small molecule inducer to the IlvY protein-DNA complex. The binding of inducer to IlvY protein does not affect the affinity of IlvY protein for the tandem operator sites. It does, however, cause a conformational change of the IlvY protein-DNA complex, which is correlated with the partial relief of an IlvY protein-induced bend of the DNA helix in the ilvC promoter region. This structural change in the IlvY protein-DNA complex results in a 100-fold increase in the affinity of RNA polymerase binding at the ilvC promoter site. The ability of a protein to regulate gene expression by ligand-responsive modulation of a protein-DNA structure is an emerging theme in gene regulation. |
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| Keywords |
Base Sequence; Binding Sites; DNA, Recombinant/metabolism; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/metabolism; DNA-Directed RNA Polymerases/metabolism; Gene Expression Regulation; Ligands; Molecular Conformation; Molecular Sequence Data; Operon; Promoter Regions, Genetic; Thermodynamics |
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