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Guaglianone G, Torrado B, Lin YF, Watkins MC, Wysocki VH, Gratton E, Nowick JS. Elucidating the Oligomerization and Cellular Interactions of a Trimer Derived from Aβ through Fluorescence and Mass Spectrometric Studies. ACS Chem Neurosci 2022; 13:2473-2482. [PMID: 35892278 PMCID: PMC9389591 DOI: 10.1021/acschemneuro.2c00313] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/15/2022] [Indexed: 01/20/2023] Open
Abstract
Aβ oligomers play a central role in the neurodegeneration observed with Alzheimer's disease. Our laboratory has developed covalently stabilized trimers derived from residues 17-36 of Aβ as model systems for studying Aβ oligomers. In the current study, we apply the emerging techniques of fluorescence lifetime imaging microscopy (FLIM) and native mass spectrometry (native MS) to better understand the assembly and interactions of the oligomer model system 2AT-L in aqueous solutions and with cells. 2AT-L and fluorescently labeled 2AT-L analogues assemble in the membrane-like environment of SDS-PAGE, showing diffuse bands of oligomers in equilibrium. Native ion mobility-mass spectrometry (native IM-MS) of 2AT-L allows for the identification of discrete oligomers in solution and shows similar patterns of oligomer formation between 2AT-L and fluorescently labeled analogues. Fluorescence microscopy with SH-SY5Y cells reveals that fluorescently labeled 2AT-L analogues colocalize within lysosomes. FLIM studies with phasor analysis further elucidate the assembly of 2AT-L within cells and establish the occurrence of FRET, indicating the presence of oligomers within cells. Collectively, these multiple complementary techniques help better understand the complex behavior of the 2AT-L model system.
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Affiliation(s)
- Gretchen Guaglianone
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
| | - Belén Torrado
- Laboratory
for Fluorescence Dynamics, Biomedical Engineering, University of California, Irvine, California 92697, United States
| | - Yu-Fu Lin
- Resource
for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
- Department
of Chemistry and Biochemistry, The Ohio
State University, Columbus, Ohio 43210, United States
| | - Matthew C. Watkins
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
| | - Vicki H. Wysocki
- Resource
for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
- Department
of Chemistry and Biochemistry, The Ohio
State University, Columbus, Ohio 43210, United States
| | - Enrico Gratton
- Laboratory
for Fluorescence Dynamics, Biomedical Engineering, University of California, Irvine, California 92697, United States
| | - James S. Nowick
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
- Department
of Pharmaceutical Sciences, University of
California, Irvine, Irvine, California 92697, United States
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Zhang S, Yoo S, Snyder DT, Katz BB, Henrickson A, Demeler B, Wysocki VH, Kreutzer AG, Nowick JS. A Disulfide-Stabilized Aβ that Forms Dimers but Does Not Form Fibrils. Biochemistry 2022; 61:252-264. [PMID: 35080857 PMCID: PMC9083094 DOI: 10.1021/acs.biochem.1c00739] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aβ dimers are a basic building block of many larger Aβ oligomers and are among the most neurotoxic and pathologically relevant species in Alzheimer's disease. Homogeneous Aβ dimers are difficult to prepare, characterize, and study because Aβ forms heterogeneous mixtures of oligomers that vary in size and can rapidly aggregate into more stable fibrils. This paper introduces AβC18C33 as a disulfide-stabilized analogue of Aβ42 that forms stable homogeneous dimers in lipid environments but does not aggregate to form insoluble fibrils. The AβC18C33 peptide is readily expressed in Escherichia coli and purified by reverse-phase HPLC to give ca. 8 mg of pure peptide per liter of bacterial culture. SDS-PAGE establishes that AβC18C33 forms homogeneous dimers in the membrane-like environment of SDS and that conformational stabilization of the peptide with a disulfide bond prevents the formation of heterogeneous mixtures of oligomers. Mass spectrometric (MS) studies in the presence of dodecyl maltoside (DDM) further confirm the formation of stable noncovalent dimers. Circular dichroism (CD) spectroscopy establishes that AβC18C33 adopts a β-sheet conformation in detergent solutions and supports a model in which the intramolecular disulfide bond induces β-hairpin folding and dimer formation in lipid environments. Thioflavin T (ThT) fluorescence assays and transmission electron microscopy (TEM) studies indicate that AβC18C33 does not undergo fibril formation in aqueous buffer solutions and demonstrate that the intramolecular disulfide bond prevents fibril formation. The recently published NMR structure of an Aβ42 tetramer (PDB: 6RHY) provides a working model for the AβC18C33 dimer, in which two β-hairpins assemble through hydrogen bonding to form a four-stranded antiparallel β-sheet. It is anticipated that AβC18C33 will serve as a stable, nonfibrilizing, and noncovalent Aβ dimer model for amyloid and Alzheimer's disease research.
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Affiliation(s)
- Sheng Zhang
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Stan Yoo
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Dalton T. Snyder
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Benjamin B. Katz
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Dr., Lethbridge, Alberta, Canada T1K 3M4
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Dr., Lethbridge, Alberta, Canada T1K 3M4
| | - Vicki H. Wysocki
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Adam G. Kreutzer
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States,Corresponding Authors: James S. Nowick – Department of Chemistry, University of California, Irvine, California 92697-2025, United States; Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-2025, United States. , Adam G. Kreutzer – Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
| | - James S. Nowick
- Department of Chemistry, University of California Irvine, Irvine, California 92697-2025, United States,Department of Pharmaceutical Sciences, University of California Irvine, Irvine, California 92697-2025, United States,Corresponding Authors: James S. Nowick – Department of Chemistry, University of California, Irvine, California 92697-2025, United States; Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-2025, United States. , Adam G. Kreutzer – Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
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Zhang S, Guaglianone G, Morris MA, Yoo S, Howitz WJ, Xing L, Zheng JG, Jusuf H, Huizar G, Lin J, Kreutzer AG, Nowick JS. Correction to "Expression of N-Terminal Cysteine Aβ 42 and Conjugation to Generate Fluorescent and Biotinylated Aβ 42". Biochemistry 2021; 60:2272-2273. [PMID: 34213906 DOI: 10.1021/acs.biochem.1c00424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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