Niu X, Adams C C, Workman J L, Guiltinan M J
Department of Horticulture, Pennsylvania State University, University Park 16802, USA.
Plant Cell. 1996 Sep;8(9):1569-87. doi: 10.1105/tpc.8.9.1569.
To investigate interactions of the basic leucine zipper transcription factor EmBP-1 with its recognition sites in nucleosomal DNA, we reconstituted an abscisic acid response element and a high-affinity binding site for EmBP-1 into human and wheat nucleosome cores in vitro. DNA binding studies demonstrated that nucleosomal elements can be bound by EmBP-1 at reduced affinities relative to naked DNA. EmBP-1 affinity was lowest when the recognition sites were positioned near the center of the nucleosome. Binding was achieved with a truncated DNA binding domain; however, binding of full-length EmBP-1 caused additional strong DNase I hypersensitivity flanking the binding sites. Similar results were observed with nucleosomes reconstituted with either human or wheat histones, demonstrating a conserved mechanism of transcription factor-nucleosome interactions. We conclude that positioning of recognition sequences on a nucleosome may play an important role in regulating interactions of EmBP-1 with its target sites in plant cells.
为了研究碱性亮氨酸拉链转录因子EmBP-1与其在核小体DNA中的识别位点之间的相互作用，我们在体外将脱落酸反应元件和EmBP-1的高亲和力结合位点重组到人和小麦核小体核心中。DNA结合研究表明，相对于裸露的DNA，核小体元件可以被EmBP-1以较低的亲和力结合。当识别位点位于核小体中心附近时，EmBP-1的亲和力最低。用截短的DNA结合结构域可实现结合；然而，全长EmBP-1的结合导致结合位点两侧出现额外的强烈DNase I超敏反应。用人组蛋白或小麦组蛋白重组的核小体也观察到了类似结果，表明转录因子与核小体相互作用的机制是保守的。我们得出结论，识别序列在核小体上的定位可能在调节植物细胞中EmBP-1与其靶位点的相互作用中起重要作用。
