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酵母RNA聚合酶I转录起始的结构见解

Structural insights into transcription initiation by yeast RNA polymerase I.

作者信息

Sadian Yashar, Tafur Lucas, Kosinski Jan, Jakobi Arjen J, Wetzel Rene, Buczak Katarzyna, Hagen Wim Jh, Beck Martin, Sachse Carsten, Müller Christoph W

机构信息

European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Heidelberg, Germany.

European Molecular Biology Laboratory (EMBL), Hamburg Unit, Hamburg, Germany.

出版信息

EMBO J. 2017 Sep 15;36(18):2698-2709. doi: 10.15252/embj.201796958. Epub 2017 Jul 24.

Abstract

In eukaryotic cells, RNA polymerase I (Pol I) synthesizes precursor ribosomal RNA (pre-rRNA) that is subsequently processed into mature rRNA. To initiate transcription, Pol I requires the assembly of a multi-subunit pre-initiation complex (PIC) at the ribosomal RNA promoter. In yeast, the minimal PIC includes Pol I, the transcription factor Rrn3, and Core Factor (CF) composed of subunits Rrn6, Rrn7, and Rrn11. Here, we present the cryo-EM structure of the 18-subunit yeast Pol I PIC bound to a transcription scaffold. The cryo-EM map reveals an unexpected arrangement of the DNA and CF subunits relative to Pol I. The upstream DNA is positioned differently than in any previous structures of the Pol II PIC. Furthermore, the TFIIB-related subunit Rrn7 also occupies a different location compared to the Pol II PIC although it uses similar interfaces as TFIIB to contact DNA. Our results show that although general features of eukaryotic transcription initiation are conserved, Pol I and Pol II use them differently in their respective transcription initiation complexes.

摘要

在真核细胞中,RNA聚合酶I(Pol I)合成前体核糖体RNA(pre-rRNA),随后将其加工成成熟的rRNA。为了启动转录,Pol I需要在核糖体RNA启动子处组装一个多亚基预起始复合物(PIC)。在酵母中,最小的PIC包括Pol I、转录因子Rrn3和由亚基Rrn6、Rrn7和Rrn11组成的核心因子(CF)。在此,我们展示了与转录支架结合的18亚基酵母Pol I PIC的冷冻电镜结构。冷冻电镜图谱揭示了DNA和CF亚基相对于Pol I的意外排列。上游DNA的定位与Pol II PIC的任何先前结构不同。此外,与Pol II PIC相比,TFIIB相关亚基Rrn7也占据不同位置,尽管它使用与TFIIB相似的界面来接触DNA。我们的结果表明,尽管真核转录起始的一般特征是保守的,但Pol I和Pol II在各自的转录起始复合物中以不同方式使用这些特征。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a8ef/5599796/ef34b6646673/EMBJ-36-2698-g002.jpg

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