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Murakami K, Sakaguchi Y, Taniwa K, Izuo N, Hanaki M, Kawase T, Hirose K, Shimizu T, Irie K. Lysine-targeting inhibition of amyloid β oligomerization by a green perilla-derived metastable chalcone in vitro and in vivo. RSC Chem Biol 2022; 3:1380-1396. [PMID: 36544574 PMCID: PMC9709778 DOI: 10.1039/d2cb00194b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/16/2022] [Indexed: 12/05/2022] Open
Abstract
Oligomers of amyloid β (Aβ) represent an early aggregative form that causes neurotoxicity in the pathogenesis of Alzheimer's disease (AD). Thus, preventing Aβ aggregation is important for preventing AD. Despite intensive studies on dietary compounds with anti-aggregation properties, some identified compounds are susceptible to autoxidation and/or hydration upon incubation in water, leaving unanswered issues regarding which active structures in metastable compounds are actually responsible for the inhibition of Aβ aggregation. In this study, we observed the site-specific inhibition of 42-mer Aβ (Aβ42) oligomerization by the green perilla-derived chalcone 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC), which was converted to its decomposed flavonoids (dDDC, 1-3) via nucleophilic aromatic substitution with water molecules. DDC suppressed Aβ42 fibrillization and slowed the transformation of the β-sheet structure, which is rich in Aβ42 aggregates. To validate the contribution of dDDC to the inhibitory effects of DDC on Aβ42 aggregation, we synthesized 1-3 and identified 3, a catechol-type flavonoid, as one of the active forms of DDC. 1H-15N SOFAST-HMQC NMR revealed that 1-3 as well as DDC could interact with residues between His13 and Leu17, which were near the intermolecular β-sheet (Gln15-Ala21). The nucleation in Aβ42 aggregates involves the rate-limiting formation of low-molecular-weight oligomers. The formation of a Schiff base with dDDC at Lys16 and Lys28 in the dimer through autoxidation of dDDC was associated with the suppression of Aβ42 nucleation. Of note, in two AD mouse models using immunoaffinity purification-mass spectrometry, adduct formation between dDDC and brain Aβ was observed in a similar manner as reported in vitro. The present findings unraveled the lysine-targeting inhibitory mechanism of metastable dietary ingredients regarding Aβ oligomerization.
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Affiliation(s)
- Kazuma Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto UniversityKyoto606-8502Japan
| | - Yoshiki Sakaguchi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto UniversityKyoto606-8502Japan
| | - Kota Taniwa
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto UniversityKyoto606-8502Japan
| | - Naotaka Izuo
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba UniversityChiba260-8670Japan
| | - Mizuho Hanaki
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto UniversityKyoto606-8502Japan
| | | | | | - Takahiko Shimizu
- Department of Endocrinology, Hematology and Gerontology, Graduate School of Medicine, Chiba UniversityChiba260-8670Japan
| | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto UniversityKyoto606-8502Japan
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Zhu S, Weber DK, Separovic F, Sani MA. Expression and purification of the native C-amidated antimicrobial peptide maculatin 1.1. J Pept Sci 2021; 27:e3330. [PMID: 33843136 DOI: 10.1002/psc.3330] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 11/09/2022]
Abstract
Maculatin 1.1 (Mac1) is an antimicrobial peptide (AMP) from an Australian tree frog and exhibits low micromolar activity against Gram-positive bacteria. The antimicrobial properties of Mac1 are linked to its disruption of bacterial lipid membranes, which has been studied extensively by in vitro nuclear magnetic resonance (NMR) spectroscopy and biophysical approaches. Although in vivo NMR has recently proven effective in probing peptide-lipid interplay in live bacterial cells, direct structural characterisation of AMPs has been prohibited by low sensitivity and overwhelming background noise. To overcome this issue, we report a recombinant expression protocol to produce isotopically enriched Mac1. We utilized a double-fusion construct to alleviate toxicity against the Escherichia coli host and generate the native N-free and C-amidated termini Mac1 peptide. The SUMO and intein tags allowed native N-terminus and C-terminal amidation, respectively, to be achieved in a one-pot reaction. The protocol yielded 0.1 mg/L of native, uniformly 15 N-labelled, Mac1, which possessed identical structure and activity to peptide obtained by solid-phase peptide synthesis.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Daniel K Weber
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
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3
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Lieblein T, Zangl R, Martin J, Hoffmann J, Hutchison MJ, Stark T, Stirnal E, Schrader T, Schwalbe H, Morgner N. Structural rearrangement of amyloid-β upon inhibitor binding suppresses formation of Alzheimer's disease related oligomers. eLife 2020; 9:59306. [PMID: 33095161 PMCID: PMC7682991 DOI: 10.7554/elife.59306] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 10/22/2020] [Indexed: 01/24/2023] Open
Abstract
The formation of oligomers of the amyloid-β peptide plays a key role in the onset of Alzheimer's disease. We describe herein the investigation of disease-relevant small amyloid-β oligomers by mass spectrometry and ion mobility spectrometry, revealing functionally relevant structural attributes. In particular, we can show that amyloid-β oligomers develop in two distinct arrangements leading to either neurotoxic oligomers and fibrils or non-toxic amorphous aggregates. Comprehending the key-attributes responsible for those pathways on a molecular level is a pre-requisite to specifically target the peptide's tertiary structure with the aim to promote the emergence of non-toxic aggregates. Here, we show for two fibril inhibiting ligands, an ionic molecular tweezer and a hydrophobic peptide that despite their different interaction mechanisms, the suppression of the fibril pathway can be deduced from the disappearance of the corresponding structure of the first amyloid-β oligomers.
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Affiliation(s)
- Tobias Lieblein
- JW Goethe-University, Institute of Physical and Theoretical Chemistry, Frankfurt, Germany
| | - Rene Zangl
- JW Goethe-University, Institute of Physical and Theoretical Chemistry, Frankfurt, Germany
| | - Janosch Martin
- JW Goethe-University, Institute of Physical and Theoretical Chemistry, Frankfurt, Germany
| | - Jan Hoffmann
- JW Goethe-University, Institute of Physical and Theoretical Chemistry, Frankfurt, Germany
| | - Marie J Hutchison
- JW Goethe-University, Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Frankfurt am Main, Germany
| | - Tina Stark
- JW Goethe-University, Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Frankfurt am Main, Germany
| | - Elke Stirnal
- JW Goethe-University, Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Frankfurt am Main, Germany
| | - Thomas Schrader
- University of Duisburg-Essen, Institute of Organic Chemistry, Essen, Germany
| | - Harald Schwalbe
- JW Goethe-University, Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Frankfurt am Main, Germany
| | - Nina Morgner
- JW Goethe-University, Institute of Physical and Theoretical Chemistry, Frankfurt, Germany
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Jäkel L, Biemans EA, Klijn CJ, Kuiperij HB, Verbeek MM. Reduced Influence of apoE on Aβ43 Aggregation and Reduced Vascular Aβ43 Toxicity as Compared with Aβ40 and Aβ42. Mol Neurobiol 2020; 57:2131-2141. [PMID: 31953617 PMCID: PMC7118029 DOI: 10.1007/s12035-020-01873-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/07/2020] [Indexed: 01/08/2023]
Abstract
The amyloid-β 43 (Aβ43) peptide has been shown to be abundantly expressed in Alzheimer's disease plaques, whereas only relatively low levels have been demonstrated in cerebral amyloid angiopathy (CAA). To better understand this discrepant distribution, we studied various biochemical properties of Aβ43, in comparison with Aβ40 and Aβ42. We assessed the interaction of Aβ43 with the three apoE isoforms (apoE2, apoE3, and apoE4) using SDS-PAGE/Western blotting and ELISA, aggregation propensity using thioflavin T assays, and cytotoxicity towards cerebrovascular cells using MTT assays. We found that Aβ43 did not differ from Aβ42 in its interaction with apoE, whereas Aβ40 had a significantly lower degree of interaction with apoE. At a molar ratio of 1:100 (apoE:Aβ), all apoE isoforms were comparably capable of inhibiting aggregation of Aβ40 and Aβ42, but not Aβ43. All Aβ variants had a concentration-dependent negative effect on metabolic activity of cerebrovascular cells. However, the degree of this effect differed for the three Aβ isoforms (Aβ40 > Aβ42 > Aβ43), with Aβ43 being the least cytotoxic peptide towards cerebrovascular cells. We conclude that Aβ43 has different biochemical characteristics compared with Aβ40 and Aβ42. Aggregation of Aβ43 is not inhibited by apoE, in contrast to the aggregation of Aβ40 and Aβ42. Furthermore, cerebrovascular cells are less sensitive towards Aβ43, compared with Aβ40 and Aβ42. In contrast, Aβ43 neither differed from Aβ42 in its aggregation propensity (in the absence of apoE) nor in its apoE-binding capacity. Altogether, our findings may provide an explanation for the lower levels of Aβ43 accumulation in cerebral vessel walls.
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Affiliation(s)
- Lieke Jäkel
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Elisanne A.L.M. Biemans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Catharina J.M. Klijn
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
| | - H. Bea Kuiperij
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marcel M. Verbeek
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Neurology, Radboud University Medical Center, 830 TML, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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A versatile method for producing labeled or unlabeled Aβ55, Aβ40, and other β-amyloid family peptides. Protein Expr Purif 2019; 162:72-82. [DOI: 10.1016/j.pep.2019.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/12/2019] [Accepted: 04/19/2019] [Indexed: 12/18/2022]
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6
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LeVatte MA, Lipfert M, Ladner-Keay C, Wishart DS. Preparation and characterization of a highly soluble Aβ 1-42 peptide variant. Protein Expr Purif 2019; 164:105480. [PMID: 31425755 DOI: 10.1016/j.pep.2019.105480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/11/2019] [Accepted: 08/15/2019] [Indexed: 01/04/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurological disease marked by the accumulation and deposition of misfolded amyloid beta or Abeta (Aβ) peptide. Two species of Aβ peptides are found in amyloid plaques, Aβ1-40 and Aβ1-42, with the latter being the more amyloidogenic of the two. Understanding how and why Aβ peptides misfold, oligomerize and form amyloid plaques requires a detailed understanding of their structure and dynamics. The poor solubility and strong aggregation tendencies of Aβ1-42 has made the isolation and characterization of its different structural isoforms (monomer, dimer, oligomer, amyloid) exceedingly difficult. Furthermore, while synthetic Aβ1-42 peptides (Aβ42syn) are readily available, the cost of isotopically labeled peptide is substantial, making their characterization by NMR spectroscopy cost prohibitive. Here we describe the design, cloning, high-level production, isotopic labeling and biophysical characterization of a modified (solubility-tagged) Aβ1-42 variant that exhibits excellent water solubility and shares similar aggregation properties as wildtype Aβ1-42. Specifically, we attached six lysines (6K) to the C-terminus of native Aβ1-42 to create a more soluble, monomeric form of Aβ1-42 called Aβ42C6K. A gene for the Aβ42C6K was designed, synthesized and cloned into Escherichia coli (E. coli) and the peptide was expressed at milligram levels. The Aβ42C6K peptide was characterized using circular dichroism (CD), NMR, electron microscopy and thioflavin T fluorescence. Its ability to form stable monomers, oligomers and fibrils under different conditions was assessed. Our results indicate that Aβ42C6K stays monomeric at high concentrations (unlike Aβ1-42) and can be induced to oligomerize and form fibrils like Aβ1-42. Our novel construct could be used to explore the structure and dynamics of Aβ1-42 as well as the interaction of ligands with Aβ1-42 via NMR.
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Affiliation(s)
- Marcia A LeVatte
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E8, Canada
| | - Matthias Lipfert
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E8, Canada
| | - Carol Ladner-Keay
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E8, Canada
| | - David S Wishart
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E8, Canada; Department of Computing Science, University of Alberta, Edmonton, AB, T6G 2E8, Canada.
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7
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Kael MA, Weber DK, Separovic F, Sani MA. Aggregation kinetics in the presence of brain lipids of Aβ(1–40) cleaved from a soluble fusion protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [DOI: 10.1016/j.bbamem.2018.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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8
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Brahmkhatri VP, Sharma N, Sunanda P, D’Souza A, Raghothama S, Atreya HS. Curcumin nanoconjugate inhibits aggregation of N-terminal region (Aβ-16) of an amyloid beta peptide. NEW J CHEM 2018. [DOI: 10.1039/c8nj03541e] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A highly stable system of a polymeric nanoparticle-encapsulated curcumin with gold nanoparticles decorated on the surface for inhibition of Aβ1–16 aggregation.
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Affiliation(s)
- Varsha P. Brahmkhatri
- NMR Research Centre
- Indian Institute of Science
- Bangalore 560012
- India
- Centre for Nano and Material Sciences
| | - Naveen Sharma
- Division of Pharmaceutical Science
- Shri Guru Raam Rai Institute of Technology and Science
- Dehradun
- India
| | | | - Aviva D’Souza
- Centre for Nano and Material Sciences
- Jain University
- Jain Global Campus
- Bengaluru 562 112
- India
| | | | - Hanudatta S. Atreya
- NMR Research Centre
- Indian Institute of Science
- Bangalore 560012
- India
- Solid State Structural Chemistry Unit
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9
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Abstract
Soluble amyloid-β (Aβ) oligomers have become a focal point in the study of Alzheimer's disease due to their ability to elicit cytotoxicity. A number of recent studies have concentrated on the structural characterization of soluble Aβ oligomers to gain insight into their mechanism of toxicity. Consequently, providing reproducible protocols for the preparation of such oligomers is of utmost importance. The method presented in this chapter details a protocol for preparing an Aβ oligomer, with a primarily disordered secondary structure, without the need for chemical modification or amino acid substitution. Due to the stability of these disordered Aβ oligomers and the reproducibility with which they form, they are amenable for biophysical and high-resolution structural characterization.
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Affiliation(s)
- Samuel A Kotler
- Biophysics Program, University of Michigan, Ann Arbor, MI, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, University of Michigan, Ann Arbor, MI, USA.
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA.
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10
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Silvers R, Colvin MT, Frederick KK, Jacavone AC, Lindquist S, Linse S, Griffin RG. Aggregation and Fibril Structure of Aβ M01-42 and Aβ 1-42. Biochemistry 2017; 56:4850-4859. [PMID: 28792214 PMCID: PMC8254419 DOI: 10.1021/acs.biochem.7b00729] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A mechanistic understanding of Aβ aggregation and high-resolution structures of Aβ fibrils and oligomers are vital to elucidating relevant details of neurodegeneration in Alzheimer's disease, which will facilitate the rational design of diagnostic and therapeutic protocols. The most detailed and reproducible insights into structure and kinetics have been achieved using Aβ peptides produced by recombinant expression, which results in an additional methionine at the N-terminus. While the length of the C-terminus is well established to have a profound impact on the peptide's aggregation propensity, structure, and neurotoxicity, the impact of the N-terminal methionine on the aggregation pathways and structure is unclear. For this reason, we have developed a protocol to produce recombinant Aβ1-42, sans the N-terminal methionine, using an N-terminal small ubiquitin-like modifier-Aβ1-42 fusion protein in reasonable yield, with which we compared aggregation kinetics with AβM01-42 containing the additional methionine residue. The data revealed that Aβ1-42 and AβM01-42 aggregate with similar rates and by the same mechanism, in which the generation of new aggregates is dominated by secondary nucleation of monomers on the surface of fibrils. We also recorded magic angle spinning nuclear magnetic resonance spectra that demonstrated that excellent spectral resolution is maintained with both AβM01-42 and Aβ1-42 and that the chemical shifts are virtually identical in dipolar recoupling experiments that provide information about rigid residues. Collectively, these results indicate that the structure of the fibril core is unaffected by N-terminal methionine. This is consistent with the recent structures of AβM01-42 in which M0 is located at the terminus of a disordered 14-amino acid N-terminal tail.
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Affiliation(s)
- Robert Silvers
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Michael T Colvin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Kendra K Frederick
- Whitehead Institute for Biomedical Research , Nine Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Angela C Jacavone
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research , Nine Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University , SE22100 Lund, Sweden
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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12
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Nuclear magnetic resonance evidence for the dimer formation of beta amyloid peptide 1-42 in 1,1,1,3,3,3-hexafluoro-2-propanol. Anal Biochem 2016; 498:59-67. [PMID: 26772162 DOI: 10.1016/j.ab.2015.12.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/04/2015] [Accepted: 12/29/2015] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease involves accumulation of senile plaques in which filamentous aggregates of amyloid beta (Aβ) peptides are deposited. Recent studies demonstrate that oligomerization pathways of Aβ peptides may be complicated. To understand the mechanisms of Aβ(1-42) oligomer formation in more detail, we have established a method to produce (15)N-labeled Aβ(1-42) suited for nuclear magnetic resonance (NMR) studies. For physicochemical studies, the starting protein material should be solely monomeric and all Aβ aggregates must be removed. Here, we succeeded in fractionating a "precipitation-resistant" fraction of Aβ(1-42) from an "aggregation-prone" fraction by high-performance liquid chromatography (HPLC), even from bacterially overexpressed Aβ(1-42). However, both Aβ(1-42) fractions after 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) treatment formed amyloid fibrils. This indicates that the "aggregation seed" was not completely monomerized during HFIP treatment. In addition, Aβ(1-42) dissolved in HFIP was found to display a monomer-dimer equilibrium, as shown by two-dimensional (1)H-(15)N NMR. We demonstrated that the initial concentration of Aβ during the HFIP pretreatment altered the kinetic profiles of Aβ fibril formation in a thioflavin T fluorescence assay. The findings described here should ensure reproducible results when studying the Aβ(1-42) peptide.
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Dammers C, Gremer L, Neudecker P, Demuth HU, Schwarten M, Willbold D. Purification and Characterization of Recombinant N-Terminally Pyroglutamate-Modified Amyloid-β Variants and Structural Analysis by Solution NMR Spectroscopy. PLoS One 2015; 10:e0139710. [PMID: 26436664 PMCID: PMC4593648 DOI: 10.1371/journal.pone.0139710] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/16/2015] [Indexed: 11/18/2022] Open
Abstract
Alzheimer’s disease (AD) is the leading cause of dementia in the elderly and is characterized by memory loss and cognitive decline. Pathological hallmark of AD brains are intracellular neurofibrillary tangles and extracellular amyloid plaques. The major component of these plaques is the highly heterogeneous amyloid-β (Aβ) peptide, varying in length and modification. In recent years pyroglutamate-modified amyloid-β (pEAβ) peptides have increasingly moved into the focus since they have been described to be the predominant species of all N-terminally truncated Aβ. Compared to unmodified Aβ, pEAβ is known to show increased hydrophobicity, higher toxicity, faster aggregation and β-sheet stabilization and is more resistant to degradation. Nuclear magnetic resonance (NMR) spectroscopy is a particularly powerful method to investigate the conformations of pEAβ isoforms in solution and to study peptide/ligand interactions for drug development. However, biophysical characterization of pEAβ and comparison to its non-modified variant has so far been seriously hampered by the lack of highly pure recombinant and isotope-enriched protein. Here we present, to our knowledge, for the first time a reproducible protocol for the production of pEAβ from a recombinant precursor expressed in E. coli in natural isotope abundance as well as in uniformly [U-15N]- or [U-13C, 15N]-labeled form, with yields of up to 15 mg/l E. coli culture broth. The chemical state of the purified protein was evaluated by RP-HPLC and formation of pyroglutamate was verified by mass spectroscopy. The recombinant pyroglutamate-modified Aβ peptides showed characteristic sigmoidal aggregation kinetics as monitored by thioflavin-T assays. The quality and quantity of produced pEAβ40 and pEAβ42 allowed us to perform heteronuclear multidimensional NMR spectroscopy in solution and to sequence-specifically assign the backbone resonances under near-physiological conditions. Our results suggest that the presented method will be useful in obtaining cost-effective high-quality recombinant pEAβ40 and pEAβ42 for further physiological and biochemical studies.
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Affiliation(s)
- Christina Dammers
- Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Lothar Gremer
- Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Philipp Neudecker
- Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Hans-Ulrich Demuth
- Fraunhofer Institute for Cell Therapy and Immunology, Dep. Molecular Drug Biochemistry and Therapy, 06120 Halle (Saale), Germany
| | - Melanie Schwarten
- Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Dieter Willbold
- Institute of Complex Systems (ICS-6) Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
- * E-mail:
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