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Sequential XylS-CTD binding to the Pm promoter induces DNA bending prior to activation.
- Source :
-
Journal of bacteriology [J Bacteriol] 2010 Jun; Vol. 192 (11), pp. 2682-90. Date of Electronic Publication: 2010 Apr 02. - Publication Year :
- 2010
-
Abstract
- XylS protein, a member of the AraC family of transcriptional regulators, comprises a C-terminal domain (CTD) involved in DNA binding and an N-terminal domain required for effector binding and protein dimerization. In the absence of benzoate effectors, the N-terminal domain behaves as an intramolecular repressor of the DNA binding domain. To date, the poor solubility properties of the full-length protein have restricted XylS analysis to genetic approaches in vivo. To characterize the molecular consequences of XylS binding to its operator, we used a recombinant XylS-CTD variant devoid of the N-terminal domain. The resulting protein was soluble and monomeric in solution and activated transcription from its cognate promoter in an effector-independent manner. XylS binding sites in the Pm promoter present an intrinsic curvature of 35 degrees centered at position -42 within the proximal site. Gel retardation and DNase footprint analysis showed XylS-CTD binding to Pm occurred sequentially: first a XylS-CTD monomer binds to the proximal site overlapping the RNA polymerase binding sequence to form complex I. This first event increased Pm bending to 50 degrees and was followed by the binding of the second monomer, which further increased the observed global curvature to 98 degrees. This generated a concomitant shift in the bending center to a region centered at position -51 when the two sites were occupied (complex II). We propose a model in which DNA structure and binding sequences strongly influence XylS binding events previous to transcription activation.
- Subjects :
- Bacterial Proteins chemistry
Bacterial Proteins genetics
Base Sequence
Chromatography, Gel
DNA genetics
DNA Footprinting
Electrophoretic Mobility Shift Assay
Escherichia coli genetics
Escherichia coli metabolism
Molecular Sequence Data
Nucleic Acid Conformation
Protein Binding genetics
Protein Binding physiology
Protein Structure, Tertiary genetics
Protein Structure, Tertiary physiology
Solubility
Bacterial Proteins metabolism
DNA chemistry
Promoter Regions, Genetic genetics
Subjects
Details
- Language :
- English
- ISSN :
- 1098-5530
- Volume :
- 192
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Journal of bacteriology
- Publication Type :
- Academic Journal
- Accession number :
- 20363935
- Full Text :
- https://doi.org/10.1128/JB.00165-10