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1H detection and dynamic nuclear polarization-enhanced NMR of Aβ 1-42 fibrils. Proc Natl Acad Sci U S A 2022; 119:2114413119. [PMID: 34969859 PMCID: PMC8740738 DOI: 10.1073/pnas.2114413119] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2021] [Indexed: 12/25/2022] Open
Abstract
Amyloid-β (Aβ) is the subject of intense scrutiny because of its close association with Alzheimer’s disease (AD), which currently afflicts about 50 million people worldwide. The results reported in this manuscript focus on the new possibilities provided by ultrafast magic-angle spinning (MAS) 1H detection and fast-MAS dynamic nuclear polarization (DNP), which have ushered in a new era for NMR-based structural biology, but whose potential has not yet been fully exploited for the structural investigation of complex amyloid assemblies. This work demonstrates the expeditious structural analysis of amyloid fibrils, without requiring preparation of large sample amounts, and sets the stage for future studies of unlabeled AD peptides derived from tissue samples available in limited quantities. Several publications describing high-resolution structures of amyloid-β (Aβ) and other fibrils have demonstrated that magic-angle spinning (MAS) NMR spectroscopy is an ideal tool for studying amyloids at atomic resolution. Nonetheless, MAS NMR suffers from low sensitivity, requiring relatively large amounts of samples and extensive signal acquisition periods, which in turn limits the questions that can be addressed by atomic-level spectroscopic studies. Here, we show that these drawbacks are removed by utilizing two relatively recent additions to the repertoire of MAS NMR experiments—namely, 1H detection and dynamic nuclear polarization (DNP). We show resolved and sensitive two-dimensional (2D) and three-dimensional (3D) correlations obtained on 13C,15N-enriched, and fully protonated samples of M0Aβ1-42 fibrils by high-field 1H-detected NMR at 23.4 T and 18.8 T, and 13C-detected DNP MAS NMR at 18.8 T. These spectra enable nearly complete resonance assignment of the core of M0Aβ1-42 (K16-A42) using submilligram sample quantities, as well as the detection of numerous unambiguous internuclear proximities defining both the structure of the core and the arrangement of the different monomers. An estimate of the sensitivity of the two approaches indicates that the DNP experiments are currently ∼6.5 times more sensitive than 1H detection. These results suggest that 1H detection and DNP may be the spectroscopic approaches of choice for future studies of Aβ and other amyloid systems.
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Scheidt HA, Das A, Korn A, Krueger M, Maiti S, Huster D. Structural characteristics of oligomers formed by pyroglutamate-modified amyloid β peptides studied by solid-state NMR. Phys Chem Chem Phys 2020; 22:16887-16895. [PMID: 32666970 DOI: 10.1039/d0cp02307h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neuronal plaques of amyloid β (Aβ) peptides of varying length carrying different posttranslational modifications represent a molecular hallmark of Alzheimer's disease. It is believed that transient oligomeric Aβ assemblies associating in early fibrillation events represent particularly cytotoxic peptide aggregates. Also, N-terminally truncated (in position 3 or 11) and pyroglutamate modified peptides exhibited an increased toxicity compared to the wildtype. In the current study, the molecular structure of oligomeric species of pGlu3-Aβ(3-40) and pGlu11-Aβ(11-40) was investigated using solid-state NMR spectroscopy. On the secondary structure level, for both modified peptides a large similarity between oligomers and mature fibrils of the modified peptides was found mainly based on 13C NMR chemical shift data. Some smaller structural differences were detected in the vicinity of the respective modification site. Also, the crucial early folding molecular contact between residues Phe19 and Leu34 could be observed for the oligomers of both modified peptide species. Therefore, it has to be concluded that the major secondary structure elements of Aβ are already present in oligomers of pGlu3-Aβ(3-40) and pGlu11-Aβ(11-40). These posttranslationally modified peptides arrange in a similar fashion as observed for wild type Aβ(1-40).
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Affiliation(s)
- Holger A Scheidt
- Institute for Medical Physics and Biophysics, Leipzig University Härtelstr. 16-18, D-04107 Leipzig, Germany.
| | - Anirban Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Alexander Korn
- Institute for Medical Physics and Biophysics, Leipzig University Härtelstr. 16-18, D-04107 Leipzig, Germany.
| | - Martin Krueger
- Institute of Anatomy, Leipzig University, Liebigstraße 13, 04103 Leipzig, Germany
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Daniel Huster
- Institute for Medical Physics and Biophysics, Leipzig University Härtelstr. 16-18, D-04107 Leipzig, Germany. and Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
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Wahlberg E, Rahman MM, Lindberg H, Gunneriusson E, Schmuck B, Lendel C, Sandgren M, Löfblom J, Ståhl S, Härd T. Identification of proteins that specifically recognize and bind protofibrillar aggregates of amyloid-β. Sci Rep 2017; 7:5949. [PMID: 28729665 PMCID: PMC5519597 DOI: 10.1038/s41598-017-06377-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/12/2017] [Indexed: 12/12/2022] Open
Abstract
Protofibrils of the 42 amino acids long amyloid-β peptide are transient pre-fibrillar intermediates in the process of peptide aggregation into amyloid plaques and are thought to play a critical role in the pathology of Alzheimer’s disease. Hence, there is a need for research reagents and potential diagnostic reagents for detection and imaging of such aggregates. Here we describe an in vitro selection of Affibody molecules that bind to protofibrils of Aβ42cc, which is a stable engineered mimic of wild type Aβ42 protofibrils. Several binders were identified that bind Aβ42cc protofibrils with low nanomolar affinities, and which also recognize wild type Aβ42 protofibrils. Dimeric head-to-tail fusion proteins with subnanomolar binding affinities, and very slow dissociation off-rates, were also constructed. A mapping of the chemical properties of the side chains onto the Affibody scaffold surface reveals three distinct adjacent surface areas of positively charged surface, nonpolar surface and a polar surface, which presumably match a corresponding surface epitope on the protofibrils. The results demonstrate that the engineered Aβ42cc is a suitable antigen for directed evolution of affinity reagents with specificity for wild type Aβ42 protofibrils.
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Affiliation(s)
- Elisabet Wahlberg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden.,Affibody AB, Gunnar Asplunds Allé 24, SE-171 69, Solna, Sweden
| | - M Mahafuzur Rahman
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden
| | - Hanna Lindberg
- Division of Protein Technology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91, Stockholm, Sweden
| | | | - Benjamin Schmuck
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden
| | - Christofer Lendel
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden.,Department of Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology (KTH), SE-100 44, Stockholm, Sweden
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden
| | - John Löfblom
- Division of Protein Technology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91, Stockholm, Sweden
| | - Stefan Ståhl
- Division of Protein Technology, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91, Stockholm, Sweden
| | - Torleif Härd
- Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala BioCenter, Box 7015, SE-750 07, Uppsala, Sweden.
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