Sekinger Edward A, Moqtaderi Zarmik, Struhl Kevin
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mol Cell. 2005 Jun 10;18(6):735-48. doi: 10.1016/j.molcel.2005.05.003.
In yeast cells, preferential accessibility of the HIS3-PET56 promoter region is determined by a general property of the DNA sequence, not by defined sequence elements. In vivo, this region is largely devoid of nucleosomes, and accessibility is directly related to reduced histone density. The HIS3-PET56 and DED1 promoter regions associate poorly with histones in vitro, indicating that intrinsic nucleosome stability is a major determinant of preferential accessibility. Specific and genome-wide analyses indicate that low nucleosome density is a very common feature of yeast promoter regions that correlates poorly with transcriptional activation. Thus, the yeast genome is organized into structurally distinct promoter and nonpromoter regions whose DNA sequences inherently differ with respect to nucleosome formation. This organization ensures that transcription factors bind preferentially to appropriate sites in promoters, rather than to the excess of irrelevant sites in nonpromoter regions.
在酵母细胞中，HIS3 - PET56启动子区域的优先可及性是由DNA序列的一般特性决定的，而非特定的序列元件。在体内，该区域基本没有核小体，可及性与组蛋白密度降低直接相关。HIS3 - PET56和DED1启动子区域在体外与组蛋白的结合较差，表明内在核小体稳定性是优先可及性的主要决定因素。特异性和全基因组分析表明，低核小体密度是酵母启动子区域非常常见的特征，与转录激活的相关性较差。因此，酵母基因组被组织成结构上不同的启动子和非启动子区域，其DNA序列在核小体形成方面本质上存在差异。这种组织方式确保转录因子优先结合到启动子中的合适位点，而不是非启动子区域中过量的无关位点。
