Similar temporal and spatial recruitment of native 19S and 20S proteasome subunits to transcriptionally active chromatin
Similar temporal and spatial recruitment of native 19S and 20S proteasome subunits to transcriptionally active chromatin
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DOI：
10.1073/pnas.1200854109
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发表时间：
2012-04-17
影响因子：
11.1
通讯作者：
Tansey, William P.
中科院分区：
文献类型：
--
作者：
Geng, Fuqiang;Tansey, William P.
最近已经清楚的是，蛋白酶体的组成部分被招募到基因转录的位置。普遍证据表明，蛋白酶体的转录相关形式是19S碱基蛋白的亚复合体，其功能是影响转录过程的依赖于ATP的伴侣。尽管有这个概念，但缺乏令人信服的证据来证明转录专用的19S碱基复合体，而20S蛋白酶体亚单位已被证明在某些情况下与染色质有关。为了深入了解被招募到染色质中的蛋白酶体的形式，我们组装了一组高度特异的抗体，在染色质免疫沉淀分析中识别天然的酵母蛋白酶体亚单位。使用这些试剂，我们发现蛋白酶体的三个主要亚组分-19S盖、19S碱基和20S核心-与酵母中激活的GAL10基因以几乎不可区分的方式相关联。我们发现，蛋白酶体亚基Rpt1、Rpt4、Rpn8、Rpn12、Pre6和Pre10在半乳糖诱导后迅速招募到GAL10。这些亚基与GAL10的整个转录部分相关，显示出几乎相同的分布模式，一旦转录关闭，它们就会迅速从染色质中解离出来。我们还发现蛋白酶体亚单位在端粒和RNA聚合酶III转录的基因上富含。我们的数据表明，蛋白酶体的转录相关形式是典型的26S复合体。
It has recently become clear that components of the proteasome are recruited to sites of gene transcription. Prevailing evidence suggests that the transcriptionally relevant form of the proteasome is a subcomplex of 19S base proteins, which functions as an ATP-dependent chaperone that influences transcriptional processes. Despite this notion, compelling evidence for a transcription-dedicated 19S base complex is lacking, and 20S proteasome subunits have been shown to associate with chromatin in some contexts. To gain insight into the form of the proteasome that is recruited to chromatin, we assembled a panel of highly specific antibodies that recognize native yeast proteasome subunits in chromatin immunoprecipitation assays. Using these reagents, we show that components from the three major subassemblies of the proteasome-19S lid, 19S base, and 20S core-associate with the activated GAL10 gene in yeast in a virtually indistinguishable manner. We find that proteasome subunits Rpt1, Rpt4, Rpn8, Rpn12, Pre6, and Pre10 are recruited to GAL10 rapidly upon galactose induction. These subunits associate with the entire transcribed portion of GAL10, display near-identical patterns of distribution, and dissociate from chromatin rapidly once transcription is shut down. We also find that proteasome subunits are enriched at telomeres and at genes transcribed by RNA polymerase III. Our data suggest that the transcriptionally relevant form of the proteasome is the canonical 26S complex.