The Tup1 corepressor directs Htz1 deposition at a specific promoter nucleosome marking the GAL1 gene for rapid activation
The Tup1 corepressor directs Htz1 deposition at a specific promoter nucleosome marking the GAL1 gene for rapid activation
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DOI：
10.1128/mcb.00238-07
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发表时间：
2007-06-01
影响因子：
5.3
通讯作者：
Tzamarias, Dimitris
中科院分区：
文献类型：
--
作者：
Gligoris, Thomas;Thireos, George;Tzamarias, Dimitris
SWR 1复合物（SWR 1-C）依赖性沉积的启动子核小体上的组蛋白变体Htz 1是典型的酿酒酵母基因的表达是经常重编程。虽然这种表观遗传标记是显着的生理重要性，的决定因素的Htz 1沉积，设置SWR 1-C占用的条件，和的影响，Htz 1在转录起始的问题，仍然没有得到解决。在这份报告中，我们通过研究GAL 1启动子来解决这些问题。我们发现，只有当GAL 1启动子受到Tup 1辅阻遏物的影响时，Htz 1才能有效地招募和转录介体。事实上，我们表明，它是Tup 1指定的启动子核小体覆盖转录起始位点的赫兹1沉积。这种沉积在转录抑制后迅速发生，并且与SWR 1复合物的Tup 1独立瞬时募集相关。我们建议，Tup 1与SWR 1-C合作，并指定在GAL 1的HTZ 1沉积，从而标记启动子快速中和其抑制作用。
The SWR1 complex (SWR1-C)-dependent deposition of the histone variant Htz1 on promoter nucleosomes is typical of Saccharomyces cerevisiae genes whose expression is frequently reprogrammed. Although this epigenetic marking is of significant physiological importance, the determinants of Htz1 deposition, the conditions that set off SWR1-C occupancy, and the implications of Htz1 in transcriptional initiation are issues that remain unresolved. In this report, we addressed these questions by investigating the GAL1 promoter. We show that Htz1 is required for efficient Mediator recruitment and transcription only when the GAL1 promoter is under the influence of the Tup1 corepressor. In fact, we show that it is Tup1 that specifies Htz1 deposition for the promoter nucleosome covering the transcription start site. This deposition occurs rapidly following transcriptional repression, and it correlates with a Tup1-independent transient recruitment of the SWR1 complex. We propose that Tup1 cooperates with SWR1-C and specifies Htz1 deposition at GAL1, thereby marking the promoter for rapid neutralization from its repressive effects.