一个转录T7RNA聚合酶的结构在从启动到延长的过渡中
Kimberly J Durniak1, Scott Bailey, Thomas A Steitz
1Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT 06520-8114, USA.
概括
结构研究揭示了T7菌体DNA依赖RNA聚合酶 (T7 RNAP) 在转录启动和延长之间如何过渡. 中间晶体结构显示促进体结合域旋转,保持DNA接触,同时适应RNA合成.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- T7菌体的DNA依赖RNA聚合酶 (T7 RNAP) 在转录启动和延长之间经历了显著的形状变化.
- 这种过渡的精确机制,特别是涉及氨基终端域,仍然不完全理解.
研究的目的:
- 阐明T7RNAP在从转录启动到延长的过渡过程中的中间结构状态.
- 提供高分辨率的结构洞察力,了解T7 RNAP.的结构动态.
主要方法:
- 使用X射线晶体学来确定T7RNAP的结构.
- 分析了T7 RNAP与促进DNA和短RNA转录 (7和8核酸) 的复合体.
主要成果:
- 晶体结构在转录过程中揭示了T7 RNAP的中间状态.
- 在合成一个8核酸RNA转录时,促进体结合域 (PBD) 和结合的促进体旋转约45度.
- 这种旋转维持了促进体接触,并扩大了不断增长的RNA-DNA异质复合体的活性部位.
结论:
- 观察到的结构变化揭示了T7 RNAP从启动到延长的途径.
- PBD旋转是适应过渡的关键机制,同时保持基本的DNA相互作用.
- 亚域H仍然处于类似启动的位置,表明氨基终端域的不均过渡.
相关概念视频
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...
Transcription Elongation Factors
Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
Transcription Elongation Factors
Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
Bacterial Transcription
RNA polymerase (RNAP) carries out DNA-dependent RNA synthesis in both bacteria and eukaryotes. Bacteria do not have a membrane-bound nucleus. So, transcription and translation occur simultaneously, on the same DNA template.
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription Attenuation in Prokaryotes
Transcriptional attenuation occurs when RNA transcription is prematurely terminated due to the formation of a terminator mRNA hairpin structure. Bacteria use these hairpins to regulate the transcription process and control the synthesis of several amino acids including histidine, lysine, threonine, and phenylalanine. Transcription attenuation takes place in the non-coding regions of mRNA.
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
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...


