Rho依存転写終結のアロステリックメカニズム
Vitaly Epshtein1, Dipak Dutta, Joseph Wade
1Department of Biochemistry, New York University School of Medicine, New York, New York 10016, USA.
Nature
|January 16, 2010
まとめ
細菌のRho因子は,転写の初期にRNAポリメラーゼと結合する. この結合は,遺伝子発現を制御するために,無活性化と解離を含む2段階の終止プロセスを引き起こす.
科学分野:
- バクテリアの転写の調節
- 遺伝子発現の分子メカニズム
- RNA-タンパク質の相互作用
背景:
- Rhoは,転写終結に不可欠なバクテリアのRNAヘリカーゼです.
- Rhoが延長複合体 (EC) と相互作用する正確なメカニズムは不明である.
- Rhoの機能を理解することは,遺伝子の発現と転写の生産性を制御する鍵です.
研究 の 目的:
- Rhoが細菌の延長複合体 (EC) と相互作用し,それを破壊するメカニズムを解明する.
- 転写終結におけるRNAP-Rho複合体の形成の役割を調査する.
- Rho依存終結に関与する重要なステップと分子プレーヤーを決定する.
主な方法:
- 転写サイクルを通してRNAポリメラーゼ (RNAP) とRhoの関連性を調査した.
- Rho依存終結の2段階のプロセスを分析しました:EC不活性化と解離.
- 終結におけるRNAP触媒センターとトリガーループドメインの役割を調べました.
主要な成果:
- 終結性Rhoは,新生トランスクリプト合成の前にRNAPと関連しています.
- RNAP-Rho複合体の形成は,終了のために不可欠です.
- Rho依存終結は,ECの急速な無活性化 (トラップ) を伴い,ゆっくりと解離する.
- EC不活性化は速度を制限するステップであり,端末の位置を決定します.
- トリガー・ループ・ドメインは,EC不活性化と解離の両方を媒介する.
結論:
- Rho依存終結は,早期のRNAP結合によって開始される2段階のアロステリックプロセスです.
- モバイルトリガーループドメインは,Rho誘発終結の重要な仲介者です.
- Rho依存と内在の終結の間の類似性は,RNAP全体で保存されたアロステリックメカニズムを示唆しています.
関連する概念動画
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...
Transcription in Prokaryotes
Transcription is a highly regulated process that converts genetic information into RNA molecules. The transcription cycle is divided into three key stages: initiation, elongation, and termination, each driven by specific molecular mechanisms.Initiation of TranscriptionIn bacteria, transcription begins when the RNA polymerase core enzyme associates with a sigma factor to form a holoenzyme. For example, the E. coli sigma factor called σ70 forms a holoenzyme, which recognizes the -10 (Pribnow box)...
Transcriptional Regulation: Riboswitches
Riboswitches are RNA elements that regulate gene expression by altering their secondary structures in response to specific effector molecules. These elements, located in the leader regions of certain mRNAs, act as transcriptional regulators by toggling between alternative conformations to control downstream gene expression. Riboswitch-mediated regulation is a precise mechanism for modulating biosynthetic pathways, as exemplified by the riboflavin biosynthesis pathway in Bacillus...
Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
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...


