A novel TBP-associated factor of SL1 functions in RNA polymerase I transcription
A novel TBP-associated factor of SL1 functions in RNA polymerase I transcription
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DOI：
10.1038/sj.emboj.7601601
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发表时间：
2007-03-21
期刊：
影响因子：
11.4
通讯作者：
Zomerdijk, Joost C. B. M.
中科院分区：
文献类型：
--
作者：
Gorski, Julia J.;Pathak, Shalini;Zomerdijk, Joost C. B. M.
在哺乳动物 RNA 聚合酶 I 转录中，SL1（TBP 和相关因子 (TAF) 的组合）对于体外核糖体 RNA 基因启动子处的预起始复合物形成至关重要。我们提供了 SL1 的新成分 TAF(I)41 (MGC5306) 的证据，该成分在 Pol I 转录中发挥作用。 TAFI41 位于核仁中的 rDNA 启动子处，与 SL1 共纯化和共免疫沉淀。核提取物中的 TAFI41 免疫耗竭可显着降低 Pol I 转录；添加 SL1 可恢复这些提取物支持 Pol I 转录的能力。在细胞中，siRNA 介导的 TAFI41 表达降低导致体内 rDNA 启动子中 SL1 的丢失，同时 rDNA 中 Pol I 的丢失以及前 rRNA 合成的减少。这些细胞的提取物支持 Pol I 转录水平的降低；在提取物中添加 SL1 可提高 Pol I 转录水平。这些数据表明 TAFI41 是转录活性 SL1 的组成部分，并暗示 SL1（包括 TAFI41 亚基）在 Pol I 募集以及体内预起始复合物形成中发挥作用。
In mammalian RNA polymerase I transcription, SL1, an assembly of TBP and associated factors (TAFs), is essential for preinitiation complex formation at ribosomal RNA gene promoters in vitro. We provide evidence for a novel component of SL1, TAF(I)41 (MGC5306), which functions in Pol I transcription. TAFI41 resides at the rDNA promoter in the nucleolus and co-purifies and co-immunoprecipitates with SL1. TAFI41 immunodepletion from nuclear extracts dramatically reduces Pol I transcription; addition of SL1 restores the ability of these extracts to support Pol I transcription. In cells, siRNA-mediated decreased expression of TAFI41 leads to loss of SL1 from the rDNA promoter in vivo, with concomitant loss of Pol I from the rDNA and reduced synthesis of the pre-rRNA. Extracts from these cells support reduced levels of Pol I transcription; addition of SL1 to the extracts raises the level of Pol I transcription. These data suggest that TAFI41 is integral to transcriptionally active SL1 and imply a role for SL1, including the TAFI41 subunit, in Pol I recruitment and, therefore, preinitiation complex formation in vivo.