Gene Looping Is Conferred by Activator-dependent Interaction of Transcription Initiation and Termination Machineries
Gene Looping Is Conferred by Activator-dependent Interaction of Transcription Initiation and Termination Machineries
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DOI：
10.1074/jbc.m109.007948
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发表时间：
2009-09-11
影响因子：
4.8
通讯作者：
Ansari, Athar
中科院分区：
文献类型：
--
作者：
El Kaderi, Belal;Medler, Scott;Ansari, Athar
在酵母和哺乳动物细胞中，基因环并置RNA聚合酶II转录基因的启动子和终止子区域。在这里，我们报告了一个激活子依赖的相互作用的转录起始和终止因子在基因循环在芽殖酵母。染色质分析表明，MET 16，INO 1，和GAL 1 p-BUD 3在激活转录过程中处于稳定的环状构型。环几乎废除的情况下，转录激活剂Met 28，Ino 2，和Gal 4的MET 16，INO 1，和GAL 1 p-BUD 3基因，分别。转录的激活子独立的增加并不伴随着环的形成，从而表明激活子在基因循环中的重要作用。活化剂不直接促进环形成，因为它们不表现出与基因的3'末端的相互作用。相反，当基因被激活并处于环状构型时，激活因子与通用转录因子TFIIB物理相互作用。在基因的转录激活状态期间，TFIIB与启动子和终止子区交联。TFIIB在终止子上的存在依赖于CF 1 3'末端加工复合物的Rna 15组分。免疫共沉淀揭示了Rna 15与TFIIB的物理相互作用。我们建议，激活剂通过与TFIIB的相互作用，促进基因的转录激活过程中的基因循环。
Gene looping juxtaposes the promoter and terminator regions of RNA polymerase II-transcribed genes in yeast and mammalian cells. Here we report an activator-dependent interaction of transcription initiation and termination factors during gene looping in budding yeast. Chromatin analysis revealed that MET16, INO1, and GAL1p-BUD3 are in a stable looped configuration during activated transcription. Looping was nearly abolished in the absence of transcription activators Met28, Ino2, and Gal4 of MET16, INO1, and GAL1p-BUD3 genes, respectively. The activator-independent increase in transcription was not accompanied by loop formation, thereby suggesting an essential role for activators in gene looping. The activators did not facilitate loop formation directly because they did not exhibit an interaction with the 3' end of the genes. Instead, activators physically interacted with the general transcription factor TFIIB when the genes were activated and in a looped configuration. TFIIB cross-linked to both the promoter and the terminator regions during the transcriptionally activated state of a gene. The presence of TFIIB on the terminator was dependent on the Rna15 component of CF1 3' end processing complex. Coimmunoprecipitation revealed a physical interaction of Rna15 with TFIIB. We propose that the activators facilitate gene looping through their interaction with TFIIB during transcriptional activation of genes.