DNA binding is not sufficient for H-NS-mediated repression of proU expression
| Autor: | Jay C. D. Hinton, Christopher F. Higgins, Bart J.A.M. Jordi, Anne E. Fielder, Christopher M. Burns, Nir Dover, David W. Ussery |
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| Rok vydání: | 1997 |
| Předmět: |
DNA
Bacterial Salmonella typhimurium Amino Acid Transport Systems Operon Recombinant Fusion Proteins Molecular Sequence Data Biology Biochemistry chemistry.chemical_compound Bacterial Proteins Transcription (biology) Genes Reporter Binding site Cloning Molecular Promoter Regions Genetic Molecular Biology Gene Psychological repression Base Sequence Cell Biology Gene Expression Regulation Bacterial beta-Galactosidase Molecular biology Chromatin DNA binding site DNA-Binding Proteins Models Structural chemistry Lac Operon Nucleic Acid Conformation Carrier Proteins DNA Bacterial Outer Membrane Proteins Plasmids Protein Binding |
| Zdroj: | The Journal of biological chemistry. 272(18) |
| ISSN: | 0021-9258 |
| Popis: | H-NS is a major component of bacterial chromatin and influences the expression of many genes. H-NS has been shown to exhibit a binding preference for certain AT-rich curved DNA elementsin vitro. In this study we have addressed the factors that determine the specificity of H-NS action in vitro andin vivo. In bandshift studies, H-NS showed a slight binding preference for all curved sequences tested whether GC-based or AT-based; the specific architecture of the curve also influenced H-NS binding. In filter retention assays little difference in affinity could be detected for any sequence tested, including the downstream regulatory element (DRE) a downstream curved DNA element required for H-NS to repress transcription of the Salmonella typhimurium proU operon in vivo. A K d of 1–2 μm was estimated for binding of H-NS to each of these sequences. In vivo, the distance between theproU promoter and the DRE, their relative orientations on the face of the DNA helix, and translation of the DRE had no major effect on proU regulation. None of the synthetic curved sequences tested could functionally replace the DRE in vivo. These data show that differential binding to curved DNA cannot account for the specificity of H-NS action in vivo.Furthermore, binding of H-NS to DNA per se is insufficient to repress the proU promoter. Thus, the DRE does not simply act as an H-NS binding site but must have a more specific role in mediating H-NS regulation of proU transcription. |
| Databáze: | OpenAIRE |
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