関連する実験動画
Updated: Jul 12, 2026

06:06
In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
宿主プログラム細胞死防御のバクテリアの阻害剤はE3ユビキチンリガゼです
Radmila Janjusevic1, Robert B Abramovitch, Gregory B Martin
1Laboratory of Structural Microbiology, Rockefeller University, New York, NY 10021, USA.
まとめ
Pseudomonas syringaeのタンパク質AvrPtoBは,植物免疫を抑制するためにホストE3ユビキチンリガスを模倣する. このバクテリアのタンパク質は,病原菌に対する植物の防御に不可欠なプログラム細胞死 (PCD) 経路を標的としています.
科学分野:
- 植物病理学 植物病理学
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
背景:
- バクテリアの病原体であるPseudomonas syringaeは,宿主プロセスを操作するためにエフェクタータンパク質を使用します.
- プログラム細胞死 (PCD) は,病原体の侵入に対する重要な植物防御機構です.
- AvrPtoBは,植物免疫に干渉することが知られているPseudomonasシリンガエエフェクターです.
研究 の 目的:
- AvrPtoBが植物免疫関連PCDを抑制する分子メカニズムを調査する.
- AvrPtoBが宿主防御抑制に関連する酵素活性を持っているかどうかを判断する.
主な方法:
- AvrPtoB.のC端領域の構造分析
- ユビキチン・リガゼの活性性を評価するためのインビトロ生化学測定法.
- AvrPtoB.で保存された残留物の変異.
- トマトの葉の機能検査で,抗PCD活性と毒性を評価する.
主要な成果:
- AvrPtoBのC末端ドメインは,真核細胞のE3ユビキチンリガゼとホモロジーを共有しています.
- AvrPtoBはE3ユビキチンリガゼ活性を示しています.
- E2酵素結合を阻害する突然変異は,AvrPtoBの in vitro リンガゼおよび in planta の抗PCD活動を廃止する.
- AvrPtoBの活動が低下すると,トマトの細菌の毒性が著しく減少する.
結論:
- Pseudomonas syringaeは,AvrPtoBをホストE3ユビキチンリガゼの分子模倣として利用しています.
- AvrPtoBのユビキチン・リゲーゼ活動は,植物PCDと毒性を抑制するために不可欠です.
- この研究は,細菌の病原体が植物の防御を無効化するために使用する新しい戦略を明らかにしています.
関連する概念動画
The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
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...
Receptor Downregulation in MVBs
Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
The EGFR can initiate signaling pathways that lead to cell proliferation, migration, and differentiation. Overexpression of EGFR stimulates cells to proliferate. Excessive EGFR activation may...
The Extrinsic Apoptotic Pathway
The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
The Intrinsic Apoptotic Pathway
Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
The Proteasome
Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...

