IRE1α识别了霍乱毒素中的结构动机,以激活未折叠的蛋白质反应
Mariska S Simpson1,2, Heidi De Luca1, Sarah Cauthorn1,3
1Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston MA, USA.
The Journal of cell biology
|April 5, 2024
概括
霍乱毒素 (CTx) 通过与特定的展开动机结合来激活内网膜传感器 IRE1α. 这种相互作用触发了展开的蛋白质反应 (UPR),并增强了细胞毒性.
科学领域:
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
- 生物化学 生物化学
背景情况:
- IRE1α是内质网膜 (ER) 中的一个关键传感器,它启动了展开的蛋白质反应 (UPR).
- 已知霍乱毒素 (CTx) 与宿主细胞内的 IRE1α 相互作用并激活它.
- 了解CTx激活IRE1α的机制,可以了解蛋白质质量控制和细胞应激反应.
研究的目的:
- 阐明霍乱毒素 (CTx) 激活IRE1α的分子机制.
- 确定涉及IRE1α识别的CTx的特定区域和展开的要求.
- 研究CTx结合对IRE1α信号传递和细胞毒性的功能后果.
主要方法:
- 在活细胞中进行近距离标记,以识别CTx.的相互作用伙伴.
- 在试验室结合试验中使用纯化的IRE1α光内域 (IRE1αLD) 和CTx片段进行结合试验.
- 针对位点的突变发生,以探讨特定CTx基因在IRE1α激活中的作用.
- 对UPR诱导和细胞毒性的评估.
主要成果:
- 近距离标记证实了CTx A1段 (CTxA1) 与活细胞中的IRE1α的同位化.
- CTxA1直接与IRE1α光膜域 (IRE1αLD) 结合,结合取决于七个残留基因的局部展开.
- 这种结合基因位于CTxA1的边缘β链中,与IRE1α C终端柔性循环竞争.
- 突变CTxA1识别动机取消了CTx诱导的IRE1α激活和UPR诱导.
结论:
- IRE1α通过CTxA1内的特定,局部展开的动机来识别CTx,而不是通过全球展开.
- CTx与IRE1α的结合与UPR信号的激活直接相关.
- CTx诱导的IRE1α激活有助于增强细胞毒性,突出了毒素诱导的细胞应激的新机制.
相关概念视频
Regulation of the Unfolded Protein Response
2.4K
Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
2.4K
The Unfolded Protein Response
4.6K
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...
4.6K
Directing Proteins to the Rough Endoplasmic Reticulum
7.2K
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
7.2K
Insertion of Single-pass Transmembrane Proteins in the RER
6.7K
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
6.7K
Molecular Chaperones and Protein Folding
17.9K
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
The...
17.9K
Export of Misfolded Proteins out of the ER
3.6K
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...
3.6K


