Sequence-directed nucleosome-depletion is sufficient to activate transcription from a yeast core promoter in vivo.
Sequence-directed nucleosome-depletion is sufficient to activate transcription from a yeast core promoter in vivo.
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DOI：
10.1016/j.bbrc.2016.05.063
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发表时间：
2016-07-22
影响因子：
3.1
通讯作者：
Shimizu M
中科院分区：
文献类型：
--
作者：
Ichikawa Y;Morohashi N;Tomita N;Mitchell AP;Kurumizaka H;Shimizu M
核小体缺失区（Nucleosome-depleted regions，NDRs）通常存在于许多酵母基因的启动子区域，由多种机制形成，包括激活子和增强子的结合、染色质重塑复合物的作用以及特定的DNA序列本身。然而，目前还不清楚NDR的形成本身是否是转录激活所必需的。在这里，我们研究了核小体组织和基因表达之间的关系，使用一个定义的酵母报告系统，由CYC 1最小的核心启动子和lacZ基因。我们引入了简单的重复序列，这些序列应该被纳入核小体中，或者被排除在TATA盒上游的核小体之外。（CTG）12、（GAA）12和（TGTAGG）6插入片段被整合到核心启动子区域的定位核小体中，并且不影响报告基因的表达。相反，（CGG）12、（TTAGGG）6、（A）34或（CG）8的插入诱导lacZ表达10-20倍。核小体作图分析显示，诱导报告基因表达的插入物阻止了核小体的形成，并在TATA盒上游产生了NDR。因此，我们的研究结果表明，由DNA序列决定的NDR形成足以在体内从核心启动子转录激活。
Nucleosome-depleted regions (NDRs) (also called nucleosome-free regions or NFRs) are often found in the promoter regions of many yeast genes, and are formed by multiple mechanisms, including the binding of activators and enhancers, the actions of chromatin remodeling complexes, and the specific DNA sequences themselves. However, it remains unclear whether NDR formation per se is essential for transcriptional activation. Here, we examined the relationship between nucleosome organization and gene expression using a defined yeast reporter system, consisting of the CYC1 minimal core promoter and the lacZ gene. We introduced simple repeated sequences that should be either incorporated in nucleosomes or excluded from nucleosomes in the site upstream of the TATA boxes. The (CTG)12, (GAA)12 and (TGTAGG)6 inserts were incorporated into a positioned nucleosome in the core promoter region, and did not affect the reporter gene expression. In contrast, the insertion of (CGG)12, (TTAGGG)6, (A)34 or (CG)8 induced lacZ expression by 10–20 fold. Nucleosome mapping analyses revealed that the inserts that induced the reporter gene expression prevented nucleosome formation, and created an NDR upstream of the TATA boxes. Thus, our results demonstrated that NDR formation dictated by DNA sequences is sufficient for transcriptional activation from the core promoter in vivo.