人間の5' --> 3'外核酵素Xrn2は,共転写分裂部位での転写終了を促進する
Steven West1, Natalia Gromak, Nick J Proudfoot
1Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
Nature
|November 27, 2004
まとめ
この研究では,ポリ (A) シグナルで作用する共転写分裂 (CoTC) 活動が,Xrn2外核酵素によるRNAの分解を開始することを明らかにしました. このプロセスは,RNAポリメラーゼII (Pol II) の解離と転写終結につながり,魚雷モデルを支持します.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝子発現の規制について
- RNA 処理 RNA 処理
背景:
- ユカリオット遺伝子の発現は,mRNA処理とRNAポリメラーゼII (Pol II) による転写終結のためのポリ (A) 信号に依存しています.
- 終結のための2つのモデルが存在します:因子が解離する反終結,および5'から3'エクソヌクレアースによる未封印のトランスクリプトの分解を含む魚雷モデル.
- トルペドモデルは,ポリアデニレーション前の読み込みトランスクリプションの観測により課題に直面しました.
研究 の 目的:
- ポリ (A) 信号によって媒介される転写終結のメカニズムを調査する.
- この過程における共転写分裂 (CoTC) と特定のエクソヌクレアゼの役割を明らかにする.
- 魚雷モデルと,真核生物の遺伝子終結における実験的観測を調和させる.
主な方法:
- ヒトβ-グロービン遺伝子ポリ (A) シグナルの下流の新生トランスクリプトの分析.
- 共同転写分裂 (CoTC) 活動とそのRNA構造の特徴.
- CoTC,エクソヌクレアゼXrn2,および転写終結の間の相互作用を調査する.
主要な成果:
- ポリ (A) シグナル付近の新生トランスクリプトは,コトランスクリプション・クリバージュ (CoTC) 活動を示す.
- CoTCは,自由RNAの5'端を生成し,5'から3'の外核酵素Xrn2.2.の基板として機能する.
- 下流RNA断片のXrn2媒介による分解は,Pol II解離と転写終結を誘導する.
結論:
- CoTCは,Xrn2.2の基板を生成することによって,終結の重要な前駆体として作用します.
- この発見は,ユカリオットにおける転写終結の魚雷モデルを強く支持しています.
- このメカニズムは,RNA処理信号がDNAテンプレートからRNAポリメラーゼIIの解離を直接引き起こす方法を説明します.
関連する概念動画
RNA Splicing
Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...
Eukaryotic RNA Polymerases
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
All three eukaryotic RNAPs require specific transcription factors, of which the...
RNA Splicing
Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...
mRNA Stability and Gene Expression
The structure and stability of mRNA molecules regulates gene expression, as mRNAs are a key step in the pathway from gene to protein. In eukaryotes, the half-life of mRNA varies from a few minutes up to several days. mRNA stability is essential in growth and development. The absence of the proteins regulating its stability, such as tristetraprolin in mice, can cause systemic issues, including bone marrow overgrowth, inflammation, and autoimmunity.
Cis-acting Elements involved in mRNA stability
Cis-acting Elements involved in mRNA stability
Eukaryotic RNA Polymerases
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
All three eukaryotic RNAPs require specific transcription factors, of which the...
Pre-mRNA Processing: Modification of pre-mRNA Ends
In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA to distinguish it from mature mRNA.
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...


