Lavigne M, Kolb A, Yeramian E, Buc H
Institut Pasteur, Unité de Physicochimie des Macromolécules Biologiques, URA 1149 du CNRS, Paris, France.
EMBO J. 1994 Oct 17;13(20):4983-90. doi: 10.1002/j.1460-2075.1994.tb06825.x.
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.
构建了5个284碱基对的微环，其报告序列位于CRP结合位点大致相对的位置。CRP位点中心与该序列之间的间距在1.2个螺旋圈范围内变化。在有无CRP的情况下，在微环和相应片段上测定了参考序列对DNA酶I的反应性。对数据进行的严格数学分析表明，在没有CRP的情况下，未观察到DNA的优选旋转方向。相反，CRP的结合以相位依赖的方式固定了微环中报告序列的旋转方向。这一结果说明了沿着DNA分子远距离传递的结构修饰。这种效应在转录起始过程中调节激活剂与聚合酶之间协同作用的程度。
