CRP fixes the rotational orientation of covalently closed DNA molecules.
Five minicircles of 284 bp were constructed with a reporter sequence located approximately opposite a CRP binding site. The spacing between the center of the CRP site and this sequence is varied within 1.2 helical turns. The reactivity of the reference sequence to DNAse I was determined on the minicircles and on the corresponding fragments, in both the absence and presence of CRP. A rigorous mathematical analysis of the data shows that in the absence of CRP no preferred rotational orientation of the DNA is observed. In contrast, binding of CRP fixes, in a phase-dependent manner, the rotational orientation of the reporter sequence in the minicircles. This result illustrates the transmission at a distance along the DNA molecule of a structural modification. Such effects modulate the extent of synergy between activators and polymerases during the initiation of transcription.
Institut Pasteur, Unité de Physicochimie des Macromolécules Biologiques, URA 1149 du CNRS, Paris, France.
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Lavigne
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Kolb
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Yeramian
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D001665:Binding Sites; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D004270:DNA, Circular / Q000737:chemistry / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011485:Protein Binding / Q000502:physiology
D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; D004270:DNA, Circular