The native-like conformation of Ure2p in fibrils assembled under physiologically relevant conditions switches to an amyloid-like conformation upon heat-treatment of the fibrils
| Autor: | F. Briki, Ronald Melki, Luc Bousset, Jean Doucet |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Amyloid
Conformational change Hot Temperature Saccharomyces cerevisiae Proteins Time Factors Prions Protein Conformation Proteolysis Saccharomyces cerevisiae Supramolecular chemistry macromolecular substances Naphthalenes Fibril Protein Structure Secondary chemistry.chemical_compound X-Ray Diffraction Structural Biology Spectroscopy Fourier Transform Infrared medicine chemistry.chemical_classification Glutathione Peroxidase Dose-Response Relationship Drug medicine.diagnostic_test biology Congo Red Polymer biology.organism_classification Glutathione Congo red Crystallography Phenotype chemistry Fiber diffraction Protein Binding |
| Zdroj: | Journal of Structural Biology. 141:132-142 |
| ISSN: | 1047-8477 |
| Popis: | The [URE3] phenotype in the yeast Saccharomyces cerevisiae is inherited by a prion mechanism involving self-propagating Ure2p aggregates. It is believed that assembly of intact Ure2p into fibrillar polymers that bind Congo Red and show yellow-green birefringence upon staining and are resistant to proteolysis is the consequence of a major change in the conformation of the protein. We recently dissected the assembly process of Ure2p and showed the protein to retain its native α-helical structure upon assembly into protein fibrils that are similar to amyloids in that they are straight, bind Congo red and show green-yellow birefringence and have an increased resistance to proteolysis ( Bousset et al., 2002 ). Here we further show using specific ligand binding, FTIR spectroscopy and X-ray fiber diffraction that Ure2p fibrils assembled under physiologically relevant conditions are devoid of a cross-β core. The X-ray fiber diffraction pattern of these fibrils reveals their well-defined axial supramolecular order. By analyzing the effect of heat-treatment on Ure2p fibrils we bring evidences for a large conformational change that occurs within the fibrils with the loss of the ligand binding capacity, decrease of the α helicity, the formation of a cross-β core and the disappearance of the axial supramolecular order. The extent of the conformational change suggests that it is not limited to the N-terminal part of Ure2p polypeptide chain. We show that the heat-treated fibrils that possess a cross-β core are unable to propagate their structural characteristic while native-like fibrils are. Finally, the potential evolution of native-like fibrils into amyloid fibrils is discussed. |
| Databáze: | OpenAIRE |
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