Efficient termination of transcription by RNA polymerase I requires the 5′ exonuclease Rat1 in yeast
Efficient termination of transcription by RNA polymerase I requires the 5′ exonuclease Rat1 in yeast
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DOI：
10.1101/gad.463708
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发表时间：
2008-04-15
影响因子：
10.5
通讯作者：
Tollervey, David
中科院分区：
文献类型：
--
作者：
El Hage, Aziz;Koper, Michal;Tollervey, David
在RNA聚合酶II对蛋白质编码基因的转录终止期间，核5'核酸外切酶Rat 1/Xrn 2降解多聚腺苷酸化位点下游的新生转录物并“鱼雷”聚合酶。我们报告说，Rat 1的活性也需要通过RNA聚合酶I（Pol I）对rDNA进行有效终止。在缺乏催化活性Rat 1或其辅因子Rai 1的菌株中，Pol I通过主要的“Reb 1依赖性”终止子（T1）读取，但在“故障安全”终止子（T2）和复制叉屏障（RFB）下游停止。Rat 1和RFB结合蛋白Fob 1的缺乏增加了T2和RFB的Pol I通读。我们建议，前rRNA的内切核酸酶Rnt 1的共转录切割产生的Rat 1/Rai 1复合物，然后降解新生的转录加载位点。当Rat 1捕获Pol I时，其被预测为在T1处暂停，转录终止。
During transcription termination by RNA polymerase II on protein-coding genes, the nuclear 5' exonuclease Rat1/Xrn2 degrades the nascent transcript downstream from the polyadenylation site and "torpedoes" the polymerase. We report that the activity of Rat1 is also required for efficient termination by RNA polymerase I (Pol I) on the rDNA. In strains lacking catalytically active Rat1 or its cofactor Rai1, Pol I reads through the major, "Reb1-dependent" terminator (T1) but stops downstream at the "fail-safe" terminator (T2) and replication fork barrier (RFB). The absence of both Rat1 and the RFB-binding protein Fob1 increased Pol I read-through of T2 and the RFB. We propose that cotranscriptional cleavage of the pre-rRNA by the endonuclease Rnt1 generates a loading site for the Rat1/Rai1 complex, which then degrades the nascent transcript. When Rat1 catches Pol I, which is predicted to be paused at T1, transcription is terminated.