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Updated: Jul 12, 2026

11:32
Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen
Published on: May 24, 2017
転写開始の構造的基礎: 4A解像度のRNAポリメラーゼホロ酵素
Katsuhiko S Murakami1, Shoko Masuda, Seth A Darst
1The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
まとめ
Thermus aquaticus RNAポリメラーゼ (RNAP) の結晶構造は,シグマサブユニットがトランスクリプション開始時に酵素の組立と機能をどのように導いているかを明らかにします. この構造はシグマを明確にします.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
背景:
- Thermus aquaticus RNAポリメラーゼ (RNAP) は,転写を開始するための重要な酵素です.
- シグマサブユニットは,プロモーター特異性とRNAPアセンブリを制御する.
- 開始複合体の構造を理解することは,転写調節の解読に不可欠です.
研究 の 目的:
- シグマサブユニットと複合したThermus aquaticus RNAポリメラーゼ (RNAP) の初期形態の結晶構造を決定する.
- 転写開始におけるRNAPコア酵素とシグマサブユニットの構造的役割を明らかにする.
- シグマサブユニットのRNAPの活性を調節し,プロモーターの認識を促進する方法を理解する.
主な方法:
- 構造を決定するために,X線結晶学を用いた.
- 判定された構造の解像度は4アングストームでした.
- 構造分析は,RNAPコア酵素 (アルファ2ベタベタオメガ) とシグマサブユニットとの相互作用に焦点を当てた.
主要な成果:
- 初期RNAPホロ酵素の結晶構造は,4アングストームの解像度で解明されました.
- RNAPとシグマサブユニット相互作用の主要な構造的特徴が特定されました.
- シグマのカルボキシル末端ドメインは空間的に分離していますが,拡張されたループによって構成的に結びついています.
- このループはRNAPアクティブサイトチャネルとRNAエグジットチャネルに影響を与えます.
結論:
- シグマサブユニットは,転写開始時にRNAポリメラーゼの位置づけと調節において重要な役割を果たします.
- シグマサブユニットの拡張ループは,活性部位と出口チャネルと相互作用し, нуклеотиド結合とRNAトランスクリプトの進行に影響を与えます.
- 前進するRNAトランスクリプトによるシグマループの異位は,中断的開始とシグマ放出を引き起こすと提案されています.
関連する概念動画
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...
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...

