人类的5' --> 3'外核酶Xrn2促进了在共同转录分离部位的转录终止
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
概括
这项研究揭示了一种同转录裂变 (CoTC) 活性,与多元A信号一起作用,启动Xrn2外核酶的RNA降解. 这一过程导致RNA聚合酶II (Pol II) 解离和转录终结,支持鱼雷模型.
科学领域:
- 分子生物学分子生物学
- 基因表达规范 基因表达规范
- 处理RNA处理RNA处理
背景情况:
- 细胞的基因表达依赖于mRNA处理和转录终止的poly(A) 信号,由RNA聚合酶II (Pol II) 进行.
- 终止存在两个模型:反终止,因子解离,鱼雷模型,涉及5'到3'外核酶降解未封闭的转录.
- 鱼雷模型面临的挑战是由于在多基化之前对读透转录的观察.
研究的目的:
- 为了研究转录终止的机制由多元A信号介导.
- 阐明共转录裂变 (CoTC) 和特定外核酶在这个过程中的作用.
- 为了使鱼雷模型与真核生物基因终结中的实验观测相协调.
主要方法:
- 对人类β-环球蛋白基因多元A) 信号下游的新生转录的分析.
- 共同转录裂变 (CoTC) 活动及其RNA结构的表征.
- 研究CoTC,外核酶Xrn2和转录终止之间的相互作用.
主要成果:
- 在poly (A) 信号附近的新生转录显示出共转录裂解 (CoTC) 活动.
- CoTC产生一个自由RNA5'端,作为5'到3'外核酶Xrn2.2.的基质.
- 下游RNA片段的Xrn2介导降解会诱导Pol II解离和转录终止.
结论:
- CoTC作为终止的关键前体,通过产生Xrn2.2.的基质来起作用.
- 这些发现强烈支持了转录终止在真核生物中的鱼雷模型.
- 这种机制解释了RNA处理信号如何直接触发RNA聚合酶II从DNA模板中的解离.
相关概念视频
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...


