核酶切割揭示了转录位点的mRNA释放与前体mRNA加工之间的联系。

Ribozyme cleavage reveals connections between mRNA release from the site of transcription and pre-mRNA processing.

作者信息

Bird Gregory, Fong Nova, Gatlin Jesse C, Farabaugh Susan, Bentley David L

机构信息

Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, UCHSC at Fitzsimons, Aurora, 80045, USA.

出版信息

Mol Cell. 2005 Dec 9;20(5):747-58. doi: 10.1016/j.molcel.2005.11.009.

DOI:10.1016/j.molcel.2005.11.009

PMID:16337598

Abstract

We report a functional connection between splicing and transcript release from the DNA. A Pol II CTD mutant inhibited not only splicing but also RNA release from the site of transcription. A ribozyme situated downstream of the gene restored accurate splicing inhibited by the CTD mutant or a mutant poly(A) site, suggesting that cleavage liberates RNA from a niche that is inaccessible to splicing factors. Although ribozyme cleavage enhanced splicing, 3' end processing was impaired, indicating that an intact RNA chain linking the poly(A) site to Pol II is required for optimal processing. Surprisingly, poly(A)(-) beta-globin mRNA with a ribozyme-generated 3' end was exported to the cytoplasm. Ribozyme cleavage can therefore substitute for normal 3' end processing in stimulating splicing and mRNA export. We propose that mRNA biogenesis is coordinated by preventing splicing near the 3' end until the transcript is released by poly(A) site cleavage.

摘要

我们报道了剪接与转录本从DNA释放之间的功能联系。一种RNA聚合酶II C末端结构域（CTD）突变体不仅抑制剪接，还抑制转录位点的RNA释放。位于基因下游的核酶可恢复被CTD突变体或突变型聚腺苷酸化（poly(A)）位点抑制的精确剪接，这表明切割作用将RNA从剪接因子无法接近的区域释放出来。尽管核酶切割增强了剪接，但3'末端加工受损，这表明连接聚腺苷酸化位点与RNA聚合酶II的完整RNA链是最佳加工所必需的。令人惊讶的是，具有核酶产生的3'末端的聚腺苷酸化缺陷型β-珠蛋白mRNA被输出到细胞质中。因此，核酶切割在刺激剪接和mRNA输出方面可以替代正常的3'末端加工。我们提出，mRNA生物合成是通过在转录本被聚腺苷酸化位点切割释放之前，防止3'末端附近的剪接来协调的。