関連する実験動画
Updated: Jul 15, 2026

15:25
Examination of the Telomere G-overhang Structure in Trypanosoma brucei
Published on: January 26, 2011
トライパノソーマ・ブルセイのRNAポリメラーゼIによって媒介される機能的なmRNAの効率的な生成
J C Zomerdijk1, R Kieft, P Borst
1Division of Molecular Biology, The Netherlands Cancer Institute, Amsterdam.
Nature
|October 24, 1991
まとめ
トライパノソーマ・ブルセイはRNAポリメラーゼIを用いて,本質的な表面抗原遺伝子を発現し,これは真核生物にとって珍しいプロセスである. このRNAポリメラーゼIの活動は,寄生虫の免疫回避戦略の鍵です.
科学分野:
- 分子生物学は分子生物学である.
- 寄生虫学とは,寄生虫学である.
- ユカリオット遺伝子の発現
背景:
- トリパノソーマ・ブルセイは,表面グリコタンパク質 (VSG) の抗原変異によって宿主の免疫を回避する.
- VSGの遺伝子発現はRNAポリメラーゼII阻害剤に対して無感性であり,代替の転写機構を示唆している.
- 高級エウカリオットは,T. brucei. と異なり,RNAポリメラーゼIのトランスクリプトを典型的にうまく処理しない.
研究 の 目的:
- T. bruceiの遺伝子発現におけるRNAポリメラーゼIの役割を調査する.
- RNAポリメラーゼIがT. brucei. で機能的なメッセンジャーRNA (mRNA) を生成できるかどうかを判断する.
- 寄生虫の免疫回避に対するRNAポリメラーゼI活性がもたらす影響を調査する.
主な方法:
- T. brucei. のRNAポリメラーゼI活性を調べました.
- ネオミシン・フォスフォトランスフェラーゼをリポーターとして使って,機能的なmRNAの生成を評価した.
- トライパノソームのmRNAキャピングメカニズムを調べた.
主要な成果:
- T. brucei RNAポリメラーゼIが機能的なmRNAを効率的に生成できることを実証しました.
- RNAポリメラーゼIが,レポーター遺伝子 (ネオミシンフォスフォトランスフェラーゼ) の発現を媒介することを示した.
- トリパノソームのトランススプライシングによる異常なmRNAキャピングプロセスを強調した.
結論:
- RNAポリメラーゼIは,T. bruceiのmRNA産生において重要な役割を果たしており,リボソームのRNA合成における役割とは異なる.
- T. bruceiにおけるユニークなmRNA処理とキャピングにより,RNAポリメラーゼIがVSG発現のための機能的なmRNAを生成することが可能である.
- このメカニズムは,寄生虫が哺乳類の宿主免疫系を回避する能力に寄与する.
関連する概念動画
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...
Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
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...
RNA Editing
RNA editing is a post-transcriptional modification where a precursor mRNA (pre-mRNA) nucleotide sequence is changed by base insertion, deletion, or modification. The extent of RNA editing varies from a few hundred bases, in mitochondrial DNA of trypanosomes, to a just single base, in nuclear genes of mammals. Even a single base change in the pre-mRNA can convert a codon for one amino acid into the codon for another amino acid or a stop codon. This type of re-coding can significantly affect 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...
Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...

