相关实验视频
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Published on: May 24, 2017
转录启动的结构基础:RNA聚合酶全酶,分辨率为4A
Katsuhiko S Murakami1, Shoko Masuda, Seth A Darst
1The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
概括
热水族RNA聚合酶 (RNAP) 的晶体结构揭示了sigma子单元如何在转录启动过程中指导酶组合和功能. 这个结构澄清了Sigma的结构.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 热水族RNA聚合酶 (RNAP) 是转录启动的关键酶.
- 西格玛子单元指导促进子特异性和RNAP组件.
- 了解启动复合体的结构对于破译转录调节至关重要.
研究的目的:
- 确定Thermus aquaticus RNA聚合酶 (RNAP) 与西格玛子单元复合的启动形式的晶体结构.
- 阐明RNAP核心酶和西格玛子单元在转录启动中的结构性作用.
- 了解西格玛子单元如何调节RNAP活动并促进促进者识别.
主要方法:
- 使用X射线结晶学来确定结构.
- 确定结构的分辨率为4安格斯特罗姆.
- 结构分析的重点是RNAP核心酶 (alpha2betabeta'omega) 和西格玛子单元之间的相互作用.
主要成果:
- 启动RNAP全酶的晶体结构在4安格斯特罗姆分辨率下得到解析.
- 确定了RNAP和西格玛子单元相互作用的关键结构特征.
- 西格玛的碳基终端域在空间上是分开的,但通过延长的循环来连接构造.
- 这一循环会影响RNAP活点通道和RNA退出通道.
结论:
- 西格玛子单元在转录启动过程中对RNA聚合酶的定位和调节起着至关重要的作用.
- 西格玛子单元的延长循环与活性部位和退出通道相互作用,影响核酸结合和RNA转录进展.
- 建议通过进步的RNA转录来取代西格玛循环,从而导致失败的启动和西格玛释放.
相关概念视频
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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
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Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
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...
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...

