Chromatin structure and expression of a gene transcribed by RNA polymerase III are independent of H2A.Z deposition
Chromatin structure and expression of a gene transcribed by RNA polymerase III are independent of H2A.Z deposition
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DOI：
10.1128/mcb.01953-07
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发表时间：
2008-04-01
影响因子：
5.3
通讯作者：
Bhargava, Purnima
中科院分区：
文献类型：
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作者：
Arimbasseri, Aneeshkumar Gopalakrishnan;Bhargava, Purnima
RNA聚合酶III(Pol III)转录的基因通常含有基因内启动子元件。其中，酵母U6单链RNA(SNR6)基因在体外被定位于其基因内框A和下游框B之间的核小体激活，两者之间的距离约为200bp。我们在这里证明了该基因区域的体内染色质结构的特征是存在一系列定位的核小体，其中只有一个在基因的5‘端具有调节作用。当基因由于营养缺乏而被抑制时，存在于体内A和B盒之间的定位的核小体不会移动。相反，在抑制条件下覆盖TATA盒的上游核小体在激活时被依赖于ATP的染色质重构体RSC向上游移动类似于50bp。它以组蛋白变异体H_2A.Z和H4K16乙酰化为标志，处于激活状态。在没有H2A.Z的情况下，基因的染色质结构不会改变，这表明H2A.Z不是建立活性染色质结构所必需的。这些结果表明，染色质结构直接参与了Pol III转录基因在体内不同活动状态下的调节。
The genes transcribed by RNA polymerase III (Pol III) generally have intragenic promoter elements. One of them, the yeast U6 snRNA (SNR6) gene is activated in vitro by a positioned nucleosome between its intragenic box A and extragenic, downstream box B separated by similar to 200 bp. We demonstrate here that the in vivo chromatin structure of the gene region is characterized by the presence of an array of positioned nucleosomes, with only one of them in the 5' end of the gene having a regulatory role. A positioned nucleosome present between boxes A and B in vivo does not move when the gene is repressed due to nutritional deprivation. In contrast, the upstream nucleosome which covers the TATA box under repressed conditions is shifted similar to 50 bp further upstream by the ATP-dependent chromatin remodeler RSC upon activation. It is marked with the histone variant H2A.Z and H4K16 acetylation in active state. In the absence of H2A.Z, the chromatin structure of the gene does not change, suggesting that H2A.Z is not required for establishing the active chromatin structure. These results show that the chromatin structure directly participates in regulation of a Pol III-transcribed gene under different states of its activity in vivo.