Acetylation by the transcriptional coactivator Gcn5 plays a novel role in co-transcriptional spliceosome assembly.
Acetylation by the transcriptional coactivator Gcn5 plays a novel role in co-transcriptional spliceosome assembly.
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DOI：
10.1371/journal.pgen.1000682
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发表时间：
2009-10
期刊：
影响因子：
4.5
通讯作者：
Johnson TL
中科院分区：
文献类型：
--
作者：
Gunderson FQ;Johnson TL
在过去的几年中，许多研究表明剪接体组装和剪接催化可以共转录地发生。然而，目前还不清楚哪些特定的转录因子在剪接与转录的偶联中起关键作用，以及它们的作用机制。在这里，我们报告的发现，Gcn 5，编码组蛋白乙酰转移酶（HAT）活性的佐贺复合物，具有遗传相互作用的基因编码的异二聚体U2 snRNP蛋白Msl 1和Lea 1。这些相互作用依赖于Gcn 5的HAT活性，表明Gcn 5 HAT活性与Msl 1/Lea 1功能之间存在功能关系。为了理解Gcn 5和Msl 1/Lea 1之间的关系，我们对Gcn 5在Msl 1和Lea 1向前mRNA的共转录募集中的作用进行了分析，发现Gcn 5 HAT活性是U2 snRNP（和随后的snRNP）组分向分支点的共转录募集所必需的，而它不是U1募集所必需的。虽然以前的研究表明，转录延长可以改变共转录前mRNA剪接，我们没有观察到这些基因在Gcn 5的情况下有缺陷的转录延长的证据，而Gcn 5依赖的组蛋白乙酰化是丰富的启动子区域。出乎意料的是，我们还观察到Msl 1富集在野生型细胞和缺乏Gcn 5的细胞的启动子区，表明Msl 1的募集在活跃的转录过程中可以独立于其关联在分支点区域发生。这些结果证明了一个新的作用，乙酰化的佐贺在共转录招募的U2 snRNP和识别的内含子分支点。前信使RNA剪接，即去除中断基因蛋白质编码序列的非编码RNA序列（内含子），是基因正常表达所必需的。虽然最近的研究表明，内含子识别开始时，RNA正在积极合成的RNA聚合酶II，很少有人知道如何参与基因转录和RNA剪接的蛋白质相互作用，以协调这两个反应。在这里，我们表明，蛋白质复合物佐贺，它允许RNA聚合酶II导航的三维结构的包装DNA的乙酰化组蛋白，有一个额外的作用前信使RNA剪接。我们的遗传分析表明，佐贺复合物与剪接机制的特定组分具有功能性相互作用。此外，佐贺的乙酰化活性，我们发现它是针对启动子结合的组蛋白的含内含子的基因，是需要适当的招聘这些组件的RNA在主动转录。我们的工作支持一个模型，其中SAGA依赖性乙酰化促进剪接机制的招聘前mRNA的适当的共转录剪接。
In the last several years, a number of studies have shown that spliceosome assembly and splicing catalysis can occur co-transcriptionally. However, it has been unclear which specific transcription factors play key roles in coupling splicing to transcription and the mechanisms through which they act. Here we report the discovery that Gcn5, which encodes the histone acetyltransferase (HAT) activity of the SAGA complex, has genetic interactions with the genes encoding the heterodimeric U2 snRNP proteins Msl1 and Lea1. These interactions are dependent upon the HAT activity of Gcn5, suggesting a functional relationship between Gcn5 HAT activity and Msl1/Lea1 function. To understand the relationship between Gcn5 and Msl1/Lea1, we carried out an analysis of Gcn5's role in co-transcriptional recruitment of Msl1 and Lea1 to pre-mRNA and found that Gcn5 HAT activity is required for co-transcriptional recruitment of the U2 snRNP (and subsequent snRNP) components to the branchpoint, while it is not required for U1 recruitment. Although previous studies suggest that transcription elongation can alter co-transcriptional pre-mRNA splicing, we do not observe evidence of defective transcription elongation for these genes in the absence of Gcn5, while Gcn5-dependent histone acetylation is enriched in the promoter regions. Unexpectedly, we also observe Msl1 enrichment in the promoter region for wild-type cells and cells lacking Gcn5, indicating that Msl1 recruitment during active transcription can occur independently of its association at the branchpoint region. These results demonstrate a novel role for acetylation by SAGA in co-transcriptional recruitment of the U2 snRNP and recognition of the intron branchpoint. Pre-messenger RNA splicing, the removal of non-coding RNA sequences (introns) that interrupt the protein-coding sequence of genes, is required for proper gene expression. While recent studies have revealed that intron recognition begins while the RNA is actively being synthesized by RNA polymerase II, little is known about how the proteins involved in gene transcription and RNA splicing interact to coordinate the two reactions. Here we show that the protein complex SAGA, which allows RNA polymerase II to navigate the three-dimensional structure of packaged DNA by acetylating histone proteins, has an additional role in pre-messenger RNA splicing. Our genetic analysis shows that the SAGA complex has functional interactions with specific components of the splicing machinery. Furthermore, SAGA's acetylation activity, which we find to be targeted toward promoter-bound histones of intron-containing genes, is required for proper recruitment of these components to RNA during active transcription. Our work supports a model whereby SAGA–dependent acetylation facilitates recruitment of the splicing machinery to the pre–mRNA for proper co-transcriptional splicing.
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DOI：
10.1083/jcb.133.4.719
发表时间：
1996-05
期刊：
The Journal of cell biology
影响因子：
--
作者：
Huang S;Spector DL
通讯作者：
Spector DL
影响因子：
7.8
作者：
Bauren, G;Jiang, WQ;Wieslander, L
通讯作者：
Wieslander, L
影响因子：
16
作者：
Görnemann, J;Kotovic, KM;Neugebauer, KM
通讯作者：
Neugebauer, KM
影响因子：
10.5
作者：
Lacadie, Scott A.;Tardiff, Daniel F.;Rosbash, Michael
通讯作者：
Rosbash, Michael
影响因子：
64.5
作者：
Holstege, FCP;Jennings, EG;Young, RA
通讯作者：
Young, RA