CCACCAでマークされたtRNAは,分解を標的とする
Jeremy E Wilusz1, Joseph M Whipple, Eric M Phizicky
1Koch Institute for Integrative Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. wilusz@mit.edu
まとめ
CCA添加酵素は,CCCAの代わりにCCACCAを添加することによって,不安定な転送RNA (tRNA) を分解するようにマークします. このプロセスは,すべての生命界で観察され,tRNAレベルを制御し,翻訳エラーを防ぐのに役立ちます.
科学分野:
- 分子生物学は分子生物学である.
- RNA 生物学 RNA 生物学
- バイオケミストリー バイオケミストリー
背景:
- 転送RNA (tRNA) は,タンパク質合成に不可欠である.
- CCA添加酵素 (ATP:tRNAヌクレオチジルトランスフェラーゼ) は,通常,tRNAの3'端にCCAを添加する.
- このCCA添加は,tRNAの機能とアミノ酸の結合に不可欠です.
研究 の 目的:
- tRNA品質管理におけるCCA添加酵素の役割を調査する.
- 不安定なtRNAsが調節されるメカニズムを決定する.
- 異なる生命体におけるCCA添加酵素機能の普遍性を探求する.
主な方法:
- CCA添加酵素の活性に関する比較分析 in vitro.
- モデル生物を用いた in vivo 研究.
- 修正されたtRNAのRNA配列決定と分析.
主要な成果:
- CCA添加酵素は,構造的に不安定なtRNAとtRNAのような小さなRNAを分解するために選択的にマークします.
- CCAの代わりに,これらの酵素は,標的RNAの3'端にCCACCA配列を追加します.
- ハイポモディフィードされた成熟tRNAもCCACCA添加を受け,迅速なtRNA崩壊経路を示しています.
結論:
- CCA添加酵素は,tRNA品質管理の重要な構成要素として機能します.
- CCACCA添加は,tRNAの豊富性を調節する普遍的なメカニズムとして機能します.
- この経路は,欠陥tRNAsを排除することによって,タンパク質翻訳中のエラーを防ぐ可能性が高い.
関連する概念動画
Export of Misfolded Proteins out of the ER
After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
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...
Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
Nonsense-mediated mRNA Decay
The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Regulated Protein Degradation
It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Regulated Protein Degradation
It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...


