来自U6-U4RNA复合体的RNA域的催化活性
J H Yang1, R Cedergren, B Nadal-Ginard
1Howard Hughes Medical Institute, Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA.
概括
对于mRNA前拼接至关重要的U6-U4RNA复合体具有类似于子头 ribozyme的保存域. 特定的突变使该复合体能够表现出RNA裂变活性,这表明它在拼接中起着催化作用.
科学领域:
- 分子生物学分子生物学
- 在RNA催化过程中.
- 基因表达 基因表达
背景情况:
- U6RNA对于核前体信使RNA (pre-mRNA) 拼接至关重要.
- U6-U4RNA复合体的结构在不同物种中保持一致.
- 在U6-U4复合体中的一个保存域与头RNA动图有相似之处.
研究的目的:
- 为了研究U6-U4RNA复合物的潜在催化活性.
- 探索U6RNA中保存的头状域的功能意义.
- 为了确定RNA修饰是否可以赋予U6-U4复合体催化性质.
主要方法:
- 对U6-U4RNA复杂二次结构的比较分析.
- 在U6和U4RNA的位点定向突变发生.
- 在体外RNA裂变试验.
- 关于RNA基质水解的特征.
主要成果:
- 在U6-U4RNA复合体中的一个保存域模仿了子头RNA图案.
- 哺乳动物U6-U4复合体没有表现出固有的催化活性.
- 在U6和U4RNA中的特定核酸替代物诱导了RNA裂变活性.
- 隔离的保存域显示了头核糖酶特征,包括RNA基质裂变.
结论:
- 该U6-U4RNA复合体包含一个功能性的头核糖酶类域.
- RNA修饰可以激活U6-U4复合体内的潜在催化潜能.
- 这种催化域可能在mRNA前拼接机制中发挥作用.
相关概念视频
Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
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...
tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...
Transcription Initiation
Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...
The promoters and enhancers and their accessory proteins allow tight regulation of...
Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
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...


