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Abstract
Ure2, the protein determinant of the Saccharomyces cerevisiae prion [URE3], has a natively disordered N-terminal domain that is important for prion formation in vivo and amyloid formation in vitro; the globular C-domain has a glutathione transferase-like fold. In the present study, we swapped the position of the N- and C-terminal regions, with or without an intervening peptide linker, to create the Ure2 variants CLN-Ure2 and CN-Ure2 respectively. The native structural content and stability of the variants were the same as wild-type Ure2, as indicated by enzymatic activity, far-UV CD analysis and equilibrium denaturation. CLN-Ure2 was able to form amyloid-like fibrils, but with a significantly longer lag time than wild-type Ure2; and the two proteins were unable to cross-seed. Under the same conditions, CN-Ure2 showed limited ability to form fibrils, but this was improved after addition of 0.03 M guanidinium chloride. As for wild-type Ure2, allosteric enzyme activity was observed in fibrils of CLN-Ure2 and CN-Ure2, consistent with retention of the native-like dimeric structure of the C-domains within the fibrils. Proteolytically digested fibrils of CLN-Ure2 and CN-Ure2 showed the same residual fibril core morphology as wild-type Ure2. The results suggest that the position of the prion domain affects the ability of Ure2 to form fibrils primarily due to effects on its flexibility.
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Fei L, Perrett S. New insights into the molecular mechanism of amyloid formation from cysteine scanning. Prion 2010; 4:9-12. [PMID: 20083897 DOI: 10.4161/pri.4.1.10670] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Our laboratory recently reported the identification of a peptide region, QVNI, within the prion domain of the yeast protein Ure2 that may act as an initiation point for fibril formation.(1) This potential amyloid-forming region, which corresponds to residues 18-21 of Ure2, was initially identified by systematic cysteine scanning of the Ure2 prion domain. The point mutant R17C, and the corresponding octapeptide CQVNIGNR, were found to form fibrils rapidly under oxidative conditions due to the formation of a disulfide bond. Deletions within the QVNI sequence cause the fibril formation ability of R17C Ure2 to be inhibited. The aggregation propensity of this region is strongly modulated by its preceding residue: replacement of R17 with a hydrophobic residue promotes fibril formation in both full-length Ure2 and in the corresponding octapeptides. The wild-type octapeptide, RQVNIGNR, also forms fibrils, and is the shortest amyloid-forming peptide found for Ure2 to date. Interestingly, the wild-type octapeptide crystallizes readily and so provides a starting point towards obtaining high resolution structural information for the amyloid core of Ure2 fibrils.
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Affiliation(s)
- Li Fei
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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Fei L, Perrett S. Disulfide bond formation significantly accelerates the assembly of Ure2p fibrils because of the proximity of a potential amyloid stretch. J Biol Chem 2009; 284:11134-41. [PMID: 19258323 DOI: 10.1074/jbc.m809673200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Aggregation of the Ure2 protein is at the origin of the [URE3] prion trait in the yeast Saccharomyces cerevisiae. The N-terminal region of Ure2p is necessary and sufficient to induce the [URE3] phenotype in vivo and to polymerize into amyloid-like fibrils in vitro. However, as the N-terminal region is poorly ordered in the native state, making it difficult to detect structural changes in this region by spectroscopic methods, detailed information about the fibril assembly process is therefore lacking. Short fibril-forming peptide regions (4-7 residues) have been identified in a number of prion and other amyloid-related proteins, but such short regions have not yet been identified in Ure2p. In this study, we identify a unique cysteine mutant (R17C) that can greatly accelerate the fibril assembly kinetics of Ure2p under oxidizing conditions. We found that the segment QVNI, corresponding to residues 18-21 in Ure2p, plays a critical role in the fast assembly properties of R17C, suggesting that this segment represents a potential amyloid-forming region. A series of peptides containing the QVNI segment were found to form fibrils in vitro. Furthermore, the peptide fibrils could seed fibril formation for wild-type Ure2p. Preceding the QVNI segment with a cysteine or a hydrophobic residue, instead of a charged residue, caused the rate of assembly into fibrils to increase greatly for both peptides and full-length Ure2p. Our results indicate that the potential amyloid stretch and its preceding residue can modulate the fibril assembly of Ure2p to control the initiation of prion formation.
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Affiliation(s)
- Li Fei
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China
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Bohic S, Murphy K, Paulus W, Cloetens P, Salomé M, Susini J, Double K. Intracellular Chemical Imaging of the Developmental Phases of Human Neuromelanin Using Synchrotron X-ray Microspectroscopy. Anal Chem 2008; 80:9557-66. [DOI: 10.1021/ac801817k] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sylvain Bohic
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Karen Murphy
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Werner Paulus
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Peter Cloetens
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Murielle Salomé
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Jean Susini
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
| | - Kay Double
- INSERM U-836 (Team 6), Rayonnement Synchrotron et Recherche Médicale, Institut des Neurosciences Grenoble (GIN), Université Joseph Fourier UMR-S 836, Grenoble, F-38042, France, Prince of Wales Medical Research Institute and the University of New South Wales, Randwick NSW, 2031, Australia, Institute of Neuropathology, University Hospital, 48149, Münster, Germany, and European Synchrotron Radiation Facility (ESRF), X-ray Imaging Group, ID22 Beamline, BP220, 38043 Grenoble Cedex, France
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