通过Ubr1介导的N-降解聚化结构见解
Man Pan1, Qingyun Zheng2,3, Tian Wang2
1Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA. panman@sjtu.edu.cn.
Nature
|November 18, 2021
概括
研究人员发现了Ubr1 E3结合酶是如何启动和延长蛋白质降解的. 化电磁结构揭示了使Ubr1成为可能的关键元素
科学领域:
- 生物化学和分子生物学
- 蛋白酶介导的蛋白质降解
- 位点化途径
背景情况:
- 该N-降解途径针对具有破坏稳定的N-终端残留的蛋白质进行蛋白质体降解.
- 在酵母中,单个亚单元E3酶Ubr1控制了Arg/N-degron通路.
- 通过Ubc2启动和延长ubiquitin链的Ubr1的精确机制仍然难以捉摸.
研究的目的:
- 阐明Ubr1介导的泛化启动和延长的机制基础.
- 描述Arg/N-degron路径中的Ubr1功能的结构决定因素.
- 提供由单个E3连接酶催化的链接特异性无化.
主要方法:
- 化学策略的开发以模仿泛素转移反应中间体.
- 电子显微镜 (cryo-EM) 用于确定Ubr1-Ubc2-ubiquitin复合物的结构.
- 复合体的结构分析代表了无处不在的启动和延伸步骤.
主要成果:
- 克里奥-EM结构显示Ubr1与Ubc2,ubiquitin和N-degron合在一起.
- 关键结构元件的识别和表征:Ubr1上的Ubc2结合区域和接受器ubiquitin结合循环.
- 这些元素对于介导无处不在的启动和延伸阶段至关重要.
结论:
- 这项研究为Ubr1的作用机制提供了前所未有的结构洞察力.
- 关键的Ubr1结构特征决定了ubiquitin链的启动和延长.
- 这些发现有助于我们更好地理解蛋白质降解中的泛素链接特异性.
相关概念视频
Regulated Protein Degradation
7.9K
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...
7.9K
Covalently Linked Protein Regulators
7.8K
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein....
These groups modify specific amino acids in a protein....
7.8K
The Proteasome
1.2K
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...
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...
1.2K
Protein Modifications in the RER
5.8K
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal...
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal...
5.8K
The Unfolded Protein Response
5.3K
The ER is the hub of protein synthesis in a cell. It has robust systems to quality control protein folding and also for degradation of terminally misfolded proteins. Under normal conditions, a small proportion of misfolded proteins that cannot be salvaged need to be transported to the cytoplasm by the ER-associated degradation or ERAD pathways. However, if the ERAD cannot handle the misfolded proteins, the cell activates the unfolded protein response or UPR to adjust the protein folding...
5.3K
Export of Misfolded Proteins out of the ER
4.1K
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...
4.1K


