Thiriet C, Hayes J J
Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA.
J Biol Chem. 1998 Aug 14;273(33):21352-8. doi: 10.1074/jbc.273.33.21352.
We demonstrate that core histones can affect the accessibility of a DNA element positioned outside of the classically defined nucleosome core region. The distance between a well positioned nucleosome and the binding site for the 5 S-specific transcription factor TFIIIA was systematically varied and the relative binding affinity for TFIIIA determined. We found that core histone-DNA interactions attenuate the affinity of TFIIIA for its cognate DNA element by a factor of 50-100-fold even when the critical binding region lies well outside of the classically defined nucleosome core region. These results have implications for the validity of parallels drawn between the accessibility of general nucleases to DNA sequences in chromatin and the activity of actual sequence-specific DNA binding factors.
我们证明核心组蛋白能够影响位于经典定义的核小体核心区域之外的DNA元件的可及性。系统地改变定位良好的核小体与5S特异性转录因子TFIIIA结合位点之间的距离，并测定TFIIIA的相对结合亲和力。我们发现，即使关键结合区域位于经典定义的核小体核心区域之外，核心组蛋白与DNA的相互作用也会使TFIIIA与其同源DNA元件的亲和力降低50至100倍。这些结果对染色质中一般核酸酶对DNA序列的可及性与实际序列特异性DNA结合因子的活性之间所做类比的有效性具有启示意义。
