The role of Rad1 in coupling mRNA 3′-end processing to transcription termination:: implications for a unified allosteric-torpedo model
The role of Rad1 in coupling mRNA 3′-end processing to transcription termination:: implications for a unified allosteric-torpedo model
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DOI：
10.1101/gad.1409106
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发表时间：
2006-04-15
影响因子：
10.5
通讯作者：
Bentley, DL
中科院分区：
文献类型：
--
作者：
Luo, WF;Johnson, AW;Bentley, DL
RNA 聚合酶 II 转录终止的鱼雷模型提出，5'-3' RNA 核酸外切酶进入 Poly(A) 切割位点，降解新生 RNA，并最终从 DNA 中取代聚合酶。然而，新生 RNA 的共转录降解尚未得到直接证实。在这里，我们报道了两种核酸外切酶 Rat1 和 Xrn1 都有助于新生 RNA 的共转录降解，但这种降解不足以引起聚合酶释放。出乎意料的是，Rat1 通过增强 T 端加工因子（包括 Pcf11 和 Rna15）的招募，在 3' 端加工和终止中发挥作用。此外，裂解因子 Pcf11 也有助于将 Rat1 募集到延伸复合物中。我们的结果提出了一个统一的变构/鱼雷模型，其中 Rat1 不是专用的终止因子，而是裂解/聚腺苷酸化装置的集成组件。
The torpedo model of transcription termination by RNA polymerase II proposes that a 5'-3' RNA exonuclease enters at the poly(A) cleavage site, degrades the nascent RNA, and eventually displaces polymerase from the DNA. Cotranscriptional degradation of nascent RNA has not been directly demonstrated, however. Here we report that two exonucleases, Rat1 and Xrn1, both contribute to cotranscriptional degradation of nascent RNA, but this degradation is not sufficient to cause polymerase release. Unexpectedly, Rat1 functions in both 3'-end processing and termination by enhancing recruitment of T-end processing factors, including Pcf11 and Rna15. In addition, the cleavage factor Pcf11 reciprocally aids in recruitment of Rat1 to the elongation complex. Our results suggest a unified allosteric/torpedo model in which Rat1 is not a dedicated termination factor, but is an integrated component of the cleavage/polyadenylation apparatus.