1
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Ohgita T, Sakai K, Fukui N, Namba N, Nakano M, Kiguchi Y, Morita I, Oyama H, Yamaki K, Nagao K, Kobayashi N, Saito H. Generation of novel anti-apoE monoclonal antibodies that selectively recognize apoE isoforms. FEBS Lett 2024; 598:902-914. [PMID: 38529702 DOI: 10.1002/1873-3468.14858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 03/27/2024]
Abstract
Apolipoprotein E (apoE) is a regulator of lipid metabolism, cholesterol transport, and the clearance and aggregation of amyloid β in the brain. The three human apoE isoforms apoE2, apoE3, and apoE4 only differ in one or two residues. Nevertheless, the functions highly depend on the isoform types and lipidated states. Here, we generated novel anti-apoE monoclonal antibodies (mAbs) and obtained an apoE4-selective mAb whose epitope is within residues 110-117. ELISA and bio-layer interferometry measurements demonstrated that the dissociation constants of mAbs are within the nanomolar range. Using the generated antibodies, we successfully constructed sandwich ELISA systems, which can detect all apoE isoforms or selectively detect apoE4. These results suggest the usability of the generated anti-apoE mAbs for selective detection of apoE isoforms.
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Affiliation(s)
- Takashi Ohgita
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
- Center for Instrumental Analysis, Kyoto Pharmaceutical University, Japan
| | - Koto Sakai
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
| | - Nodoka Fukui
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
| | - Norihiro Namba
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
| | - Miyu Nakano
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
| | - Yuki Kiguchi
- Laboratory of Bioanalytical Chemistry, Kobe Pharmaceutical University, Japan
| | - Izumi Morita
- Laboratory of Bioanalytical Chemistry, Kobe Pharmaceutical University, Japan
| | - Hiroyuki Oyama
- Laboratory of Bioanalytical Chemistry, Kobe Pharmaceutical University, Japan
| | - Kouya Yamaki
- Laboratory of Pharmacology, Kobe Pharmaceutical University, Japan
| | - Kohjiro Nagao
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
| | - Norihiro Kobayashi
- Laboratory of Bioanalytical Chemistry, Kobe Pharmaceutical University, Japan
| | - Hiroyuki Saito
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Japan
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2
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Namba N, Ohgita T, Tamagaki-Asahina H, Nishitsuji K, Shimanouchi T, Sato T, Saito H. Amyloidogenic 60-71 deletion/ValThr insertion mutation of apolipoprotein A-I generates a new aggregation-prone segment that promotes nucleation through entropic effects. Sci Rep 2023; 13:18514. [PMID: 37898709 PMCID: PMC10613298 DOI: 10.1038/s41598-023-45803-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 10/24/2023] [Indexed: 10/30/2023] Open
Abstract
The N-terminal fragment of apolipoprotein A-I (apoA-I), comprising residues 1-83, contains three segments prone to aggregation: residues 14-22, 53-58, and 67-72. We previously demonstrated that residues 14-22 are critical in apoA-I fibril formation while residues 53-58 entropically drove the nucleation process. Here, we investigated the impact of amyloidogenic mutations (Δ60-71/VT, Δ70-72, and F71Y) located around residues 67-72 on fibril formation by the apoA-I 1-83 fragment. Thioflavin T fluorescence assay demonstrated that the Δ60-71/VT mutation significantly enhances both nucleation and fibril elongation rates, whereas the Δ70-72 and F71Y mutations had minimal effects. Circular dichroism measurements and microscopic observations revealed that all variant fragments formed straight fibrils, transitioning from random coils to β-sheet structures. Kinetic analysis demonstrated that primary nucleation is the dominant step in fibril formation, with fibril elongation reaching saturation at high protein concentrations. Thermodynamically, both nucleation and fibril elongation were enthalpically and entropically unfavorable in all apoA-I 1-83 variants, in which the entropic barrier of nucleation was almost eliminated for the Δ60-71/VT variant. Taken together, our results suggest the presence of new aggregation-prone segment in the Δ60-71/VT variant that promotes nucleation through entropic effects.
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Affiliation(s)
- Norihiro Namba
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Takashi Ohgita
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Hiroko Tamagaki-Asahina
- Division of Liberal Arts Sciences, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Kazuchika Nishitsuji
- Department of Biochemistry, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Toshinori Shimanouchi
- Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan
| | - Takeshi Sato
- Division of Liberal Arts Sciences, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Hiroyuki Saito
- Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan.
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3
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Rayan B, Barnea E, Khokhlov A, Upcher A, Landau M. Differential fibril morphologies and thermostability determine functional roles of Staphylococcus aureus PSMα1 and PSMα3. Front Mol Biosci 2023; 10:1184785. [PMID: 37469708 PMCID: PMC10353841 DOI: 10.3389/fmolb.2023.1184785] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023] Open
Abstract
Phenol-soluble modulins (PSMs) are virulent peptides secreted by staphylococci that undergo self-assembly into amyloid fibrils. This study focuses on Staphylococcus aureus PSMα1 and PSMα3, which share homologous sequences but exhibit distinct amyloid fibril structures. Upon subjecting PSMα1 to an 80°C heat shock, it fibrillates into cross-β structures, resulting in the loss of cytotoxic activity. Conversely, PSMα3 cross-α fibrils undergo reversible disaggregation upon heat shock, leading to the recovery of cytotoxicity. The differential thermostability probably arises from the presence of hydrogen bonds along the β-strands within the β-sheets of the cross-β fibrils. We propose that the breakdown of PSMα3 fibrils into soluble species, potentially co-aggregating with membrane lipids, is crucial for its toxic process and enables the reversible modulation of its biological activity under stress conditions. In contrast, the formation of robust and irreversible cross-β fibrils by PSMα1 corresponds to its role in biofilm stability. These findings emphasize how the unique fibril morphologies and thermostability of PSMα1 and PSMα3 shape their functional roles in various environments of S. aureus.
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Affiliation(s)
- Bader Rayan
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Eilon Barnea
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Alexander Khokhlov
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Alexander Upcher
- Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva, Israel
| | - Meytal Landau
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- Centre for Structural Systems Biology (CSSB), Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- The Center for Experimental Medicine, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
- European Molecular Biology Laboratory (EMBL), Hamburg, Germany
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4
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Bonilha I, Luchiari B, Nadruz W, Sposito AC. Very low HDL levels: clinical assessment and management. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2023; 67:3-18. [PMID: 36651718 PMCID: PMC9983789 DOI: 10.20945/2359-3997000000585] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In individuals with very low high-density lipoprotein (HDL-C) cholesterol, such as Tangier disease, LCAT deficiency, and familial hypoalphalipoproteinemia, there is an increased risk of premature atherosclerosis. However, analyzes based on comparisons of populations with small variations in HDL-C mediated by polygenic alterations do not confirm these findings, suggesting that there is an indirect association or heterogeneity in the pathophysiological mechanisms related to the reduction of HDL-C. Trials that evaluated some of the HDL functions demonstrate a more robust degree of association between the HDL system and atherosclerotic risk, but as they were not designed to modify lipoprotein functionality, there is insufficient data to establish a causal relationship. We currently have randomized clinical trials of therapies that increase HDL-C concentration by various mechanisms, and this HDL-C elevation has not independently demonstrated a reduction in the risk of cardiovascular events. Therefore, this evidence shows that (a) measuring HDL-C as a way of estimating HDL-related atheroprotective system function is insufficient and (b) we still do not know how to increase cardiovascular protection with therapies aimed at modifying HDL metabolism. This leads us to a greater effort to understand the mechanisms of molecular action and cellular interaction of HDL, completely abandoning the traditional view focused on the plasma concentration of HDL-C. In this review, we will detail this new understanding and the new horizon for using the HDL system to mitigate residual atherosclerotic risk.
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Affiliation(s)
- Isabella Bonilha
- Universidade de Campinas (Unicamp), Laboratório de Biologia Vascular e Aterosclerose (AtheroLab), Divisão de Cardiologia, Campinas, SP, Brasil
| | - Beatriz Luchiari
- Universidade de Campinas (Unicamp), Laboratório de Biologia Vascular e Aterosclerose (AtheroLab), Divisão de Cardiologia, Campinas, SP, Brasil
| | - Wilson Nadruz
- Universidade de Campinas (Unicamp), Divisão de Cardiologia, Campinas, SP, Brasil
| | - Andrei C Sposito
- Universidade de Campinas (Unicamp), Laboratório de Biologia Vascular e Aterosclerose (AtheroLab), Divisão de Cardiologia, Campinas, SP, Brasil,
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5
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Ohgita T, Furutani Y, Nakano M, Hattori M, Suzuki A, Nakagawa M, Naniwa S, Morita I, Oyama H, Nishitsuji K, Kobayashi N, Saito H. Novel conformation‐selective monoclonal antibodies against apoA‐I amyloid fibrils. FEBS J 2021. [DOI: 10.1111/febs.15487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Takashi Ohgita
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Yuki Furutani
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Miyu Nakano
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Megumi Hattori
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Ayane Suzuki
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Miho Nakagawa
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Sera Naniwa
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Izumi Morita
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Hiroyuki Oyama
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | | | - Norihiro Kobayashi
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
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6
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Kurimitsu N, Mizuguchi C, Fujita K, Taguchi S, Ohgita T, Nishitsuji K, Shimanouchi T, Saito H. Phosphatidylethanolamine accelerates aggregation of the amyloidogenic N-terminal fragment of apoA-I. FEBS Lett 2020; 594:1443-1452. [PMID: 31968125 DOI: 10.1002/1873-3468.13737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/28/2019] [Accepted: 01/02/2020] [Indexed: 12/13/2022]
Abstract
Membrane lipid composition is known to influence aggregation and fibril formation of many amyloidogenic proteins. Here, we found that phosphatidylethanolamine (PE) accelerates aggregation of the N-terminal 1-83 fragment of an amyloidogenic G26R variant of apoA-I on lipid membranes. Circular dichroism and isothermal titration calorimetry measurements demonstrated that PE does not affect the α-helical structure and lipid binding property of apoA-I 1-83/G26R. Rather, fluorescence measurements indicated that PE induces more ordered lipid packing at the interfacial and acyl chain regions, providing more hydrophobic environments especially around the highly amyloidogenic regions in apoA-I on the membrane surface. These results suggest that PE promotes aggregation of the amyloidogenic N-terminal fragment of apoA-I on lipid membranes by inducing hydrophobic membrane environments.
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Affiliation(s)
- Naoko Kurimitsu
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Chiharu Mizuguchi
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Kaho Fujita
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Suzuno Taguchi
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Takashi Ohgita
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | | | - Toshinori Shimanouchi
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
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7
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Mizuguchi C, Nakagawa M, Namba N, Sakai M, Kurimitsu N, Suzuki A, Fujita K, Horiuchi S, Baba T, Ohgita T, Nishitsuji K, Saito H. Mechanisms of aggregation and fibril formation of the amyloidogenic N-terminal fragment of apolipoprotein A-I. J Biol Chem 2019; 294:13515-13524. [PMID: 31341020 DOI: 10.1074/jbc.ra119.008000] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 07/20/2019] [Indexed: 01/26/2023] Open
Abstract
The N-terminal (1-83) fragment of the major constituent of plasma high-density lipoprotein, apolipoprotein A-I (apoA-I), strongly tends to form amyloid fibrils, leading to systemic amyloidosis. Here, using a series of deletion variants, we examined the roles of two major amyloidogenic segments (residues 14-22 and 50-58) in the aggregation and fibril formation of an amyloidogenic G26R variant of the apoA-I 1-83 fragment (apoA-I 1-83/G26R). Thioflavin T fluorescence assays and atomic force microscopy revealed that elimination of residues 14-22 completely inhibits fibril formation of apoA-I 1-83/G26R, whereas Δ32-40 and Δ50-58 variants formed fibrils with markedly reduced nucleation and fibril growth rates. CD measurements revealed structural transitions from random coil to β-sheet structures in all deletion variants except for the Δ14-22 variant, indicating that residues 14-22 are critical for the β-transition and fibril formation. Thermodynamic analysis of the kinetics of fibril formation by apoA-I 1-83/G26R indicated that both nucleation and fibril growth are enthalpically unfavorable, whereas entropically, nucleation is favorable, but fibril growth is unfavorable. Interestingly, the nucleation of the Δ50-58 variant was entropically unfavorable, indicating that residues 50-58 entropically promote the nucleation step in fibril formation of apoA-I 1-83/G26R. Moreover, a residue-level structural investigation of apoA-I 1-83/G26R fibrils with site-specific pyrene labeling indicated that the two amyloidogenic segments are in close proximity to form an amyloid core structure, whereas the N- and C-terminal tail regions are excluded from the amyloid core. These results provide critical insights into the aggregation mechanism and fibril structure of the amyloidogenic N-terminal fragment of apoA-I.
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Affiliation(s)
- Chiharu Mizuguchi
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Miho Nakagawa
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Norihiro Namba
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Misae Sakai
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Naoko Kurimitsu
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Ayane Suzuki
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Kaho Fujita
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Sayaka Horiuchi
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Teruhiko Baba
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Takashi Ohgita
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - Kazuchika Nishitsuji
- Department of Biochemistry, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan.
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8
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Gorbenko GP, Trusova V, Mizuguchi C, Saito H. Lipid Bilayer Interactions of Amyloidogenic N-Terminal Fragment of Apolipoprotein A-I Probed by Förster Resonance Energy Transfer and Molecular Dynamics Simulations. J Fluoresc 2018; 28:1037-1047. [DOI: 10.1007/s10895-018-2267-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Accepted: 07/10/2018] [Indexed: 11/25/2022]
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9
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Effect of Phosphatidylserine and Cholesterol on Membrane-mediated Fibril Formation by the N-terminal Amyloidogenic Fragment of Apolipoprotein A-I. Sci Rep 2018; 8:5497. [PMID: 29615818 PMCID: PMC5882889 DOI: 10.1038/s41598-018-23920-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/22/2018] [Indexed: 01/31/2023] Open
Abstract
Here, we examined the effects of phosphatidylserine (PS) and cholesterol on the fibril-forming properties of the N-terminal 1‒83 fragment of an amyloidogenic G26R variant of apoA-I bound to small unilamellar vesicles. A thioflavin T fluorescence assay together with microscopic observations showed that PS significantly retards the nucleation step in fibril formation by apoA-I 1‒83/G26R, whereas cholesterol slightly enhances fibril formation. Circular dichroism analyses demonstrated that PS facilitates a structural transition from random coil to α-helix in apoA-I 1‒83/G26R with great stabilization of the α-helical structure upon lipid binding. Isothermal titration calorimetry measurements revealed that PS induces a marked increase in capacity for binding of apoA-I 1‒83/G26R to the membrane surface, perhaps due to electrostatic interactions of positively charged amino acids in apoA-I with PS. Such effects of PS to enhance lipid interactions and inhibit fibril formation of apoA-I were also observed for the amyloidogenic region-containing apoA-I 8‒33/G26R peptide. Fluorescence measurements using environment-sensitive probes indicated that PS induces a more solvent-exposed, membrane-bound conformation in the amyloidogenic region of apoA-I without affecting membrane fluidity. Since cell membranes have highly heterogeneous lipid compositions, our findings may provide a molecular basis for the preferential deposition of apoA-I amyloid fibrils in tissues and organs.
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10
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Gaglione R, Smaldone G, Di Girolamo R, Piccoli R, Pedone E, Arciello A. Cell milieu significantly affects the fate of AApoAI amyloidogenic variants: predestination or serendipity? Biochim Biophys Acta Gen Subj 2017; 1862:377-384. [PMID: 29174954 DOI: 10.1016/j.bbagen.2017.11.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/17/2017] [Accepted: 11/21/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Specific apolipoprotein A-I variants are associated to severe hereditary amyloidoses. The organ distribution of AApoAI amyloidosis seems to depend on the position of the mutation, since mutations in residues from 1 to 75 are mainly associated to hepatic and renal amyloidosis, while mutations in residues from 173 to 178 are mostly responsible for cardiac, laryngeal, and cutaneous amyloidosis. Molecular bases of this tissue specificity are still poorly understood, but it is increasingly emerging that protein destabilization induced by amyloidogenic mutations is neither necessary nor sufficient for amyloidosis development. METHODS By using a multidisciplinary approach, including circular dichroism, dynamic light scattering, spectrofluorometric and atomic force microscopy analyses, the effect of target cells on the conformation and fibrillogenic pathway of the two AApoAI amyloidogenic variants AApoAIL75P and AApoAIL174S has been monitored. RESULTS Our data show that specific cell milieus selectively affect conformation, aggregation propensity and fibrillogenesis of the two AApoAI amyloidogenic variants. CONCLUSIONS An intriguing picture emerged indicating that defined cell contexts selectively induce fibrillogenesis of specific AApoAI variants. GENERAL SIGNIFICANCE An innovative methodological approach, based on the use of whole intact cells to monitor the effects of cell context on AApoAI variants fibrillogenic pathway, has been set up.
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Affiliation(s)
- Rosa Gaglione
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy
| | | | - Rocco Di Girolamo
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy
| | - Renata Piccoli
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy; Istituto Nazionale di Biostrutture e Biosistemi (INBB), Italy
| | - Emilia Pedone
- Istituto di Biostrutture e Bioimmagini, CNR, Naples, Italy; Research Centre on Bioactive Peptides (CIRPeB), University of Naples Federico II, Via Mezzocannone 16, 80134 Naples, Italy.
| | - Angela Arciello
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy; Istituto Nazionale di Biostrutture e Biosistemi (INBB), Italy.
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11
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Arciello A, Piccoli R, Monti DM. Apolipoprotein A-I: the dual face of a protein. FEBS Lett 2016; 590:4171-4179. [DOI: 10.1002/1873-3468.12468] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/12/2016] [Accepted: 10/24/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Angela Arciello
- Department of Chemical Sciences; University of Naples Federico II; Italy
- Istituto Nazionale di Biostrutture e Biosistemi (INBB); Rome Italy
| | - Renata Piccoli
- Department of Chemical Sciences; University of Naples Federico II; Italy
- Istituto Nazionale di Biostrutture e Biosistemi (INBB); Rome Italy
| | - Daria Maria Monti
- Department of Chemical Sciences; University of Naples Federico II; Italy
- Istituto Nazionale di Biostrutture e Biosistemi (INBB); Rome Italy
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12
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Mikawa S, Mizuguchi C, Nishitsuji K, Baba T, Shigenaga A, Shimanouchi T, Sakashita N, Otaka A, Akaji K, Saito H. Heparin promotes fibril formation by the N-terminal fragment of amyloidogenic apolipoprotein A-I. FEBS Lett 2016; 590:3492-3500. [DOI: 10.1002/1873-3468.12426] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/05/2016] [Accepted: 09/11/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Shiho Mikawa
- Department of Biophysical Chemistry; Kyoto Pharmaceutical University; Japan
- Institute of Biomedical Sciences; Graduate School of Pharmaceutical Sciences; Tokushima University; Japan
| | - Chiharu Mizuguchi
- Department of Biophysical Chemistry; Kyoto Pharmaceutical University; Japan
- Institute of Biomedical Sciences; Graduate School of Pharmaceutical Sciences; Tokushima University; Japan
| | - Kazuchika Nishitsuji
- Department of Molecular Pathology; Institute of Biomedical Sciences; Tokushima University Graduate School; Japan
| | - Teruhiko Baba
- Biotechnology Research Institute for Drug Discovery; National Institute of Advanced Industrial Science and Technology (AIST); Tsukuba Japan
| | - Akira Shigenaga
- Institute of Biomedical Sciences; Graduate School of Pharmaceutical Sciences; Tokushima University; Japan
| | | | - Naomi Sakashita
- Department of Molecular Pathology; Institute of Biomedical Sciences; Tokushima University Graduate School; Japan
| | - Akira Otaka
- Institute of Biomedical Sciences; Graduate School of Pharmaceutical Sciences; Tokushima University; Japan
| | - Kenichi Akaji
- Department of Medicinal Chemistry; Kyoto Pharmaceutical University; Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry; Kyoto Pharmaceutical University; Japan
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13
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Protein conformational perturbations in hereditary amyloidosis: Differential impact of single point mutations in ApoAI amyloidogenic variants. Biochim Biophys Acta Gen Subj 2016; 1860:434-44. [DOI: 10.1016/j.bbagen.2015.10.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/15/2015] [Accepted: 10/23/2015] [Indexed: 12/31/2022]
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14
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Khan JM, Khan MS, Ali MS, Al-Shabib NA, Khan RH. Cetyltrimethylammonium bromide (CTAB) promote amyloid fibril formation in carbohydrate binding protein (concanavalin A) at physiological pH. RSC Adv 2016. [DOI: 10.1039/c6ra03707k] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Low concentration of CTAB provoked cross β-sheet formation whereas high concentrations of CTAB direct to alpha helix induction in Con A.
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Affiliation(s)
- Javed Masood Khan
- Department of Food Science and Nutrition
- Faculty of Food and Agricultural Sciences
- King Saud University
- 2460 Riyadh 11451
- Saudi Arabia
| | - Mohd Shahnawaz Khan
- Protein Research Chair
- Department of Biochemistry
- College of Science
- King Saud University
- Riyadh
| | - Mohd Sajid Ali
- Department of Chemistry
- King Saud University
- Riyadh 11451
- Saudi Arabia
| | - Nasser Abdulatif Al-Shabib
- Department of Food Science and Nutrition
- Faculty of Food and Agricultural Sciences
- King Saud University
- 2460 Riyadh 11451
- Saudi Arabia
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit
- Aligarh Muslim University
- Aligarh
- India
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15
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Mizuguchi C, Ogata F, Mikawa S, Tsuji K, Baba T, Shigenaga A, Shimanouchi T, Okuhira K, Otaka A, Saito H. Amyloidogenic Mutation Promotes Fibril Formation of the N-terminal Apolipoprotein A-I on Lipid Membranes. J Biol Chem 2015; 290:20947-20959. [PMID: 26175149 DOI: 10.1074/jbc.m115.664227] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Indexed: 02/01/2023] Open
Abstract
The N-terminal amino acid 1-83 fragment of apolipoprotein A-I (apoA-I) has a strong propensity to form amyloid fibrils at physiological neutral pH. Because apoA-I has an ability to bind to lipid membranes, we examined the effects of the lipid environment on fibril-forming properties of the N-terminal fragment of apoA-I variants. Thioflavin T fluorescence assay as well as fluorescence and transmission microscopies revealed that upon lipid binding, fibril formation by apoA-I 1-83 is strongly inhibited, whereas the G26R mutant still retains the ability to form fibrils. Such distinct effects of lipid binding on fibril formation were also observed for the amyloidogenic prone region-containing peptides, apoA-I 8-33 and 8-33/G26R. This amyloidogenic region shifts from random coil to α-helical structure upon lipid binding. The G26R mutation appears to prevent this helix transition because lower helical propensity and more solvent-exposed conformation of the G26R variant upon lipid binding were observed in the apoA-I 1-83 fragment and 8-33 peptide. With a partially α-helical conformation induced by the presence of 2,2,2-trifluoroethanol, fibril formation by apoA-I 1-83 was strongly inhibited, whereas the G26R variant can form amyloid fibrils. These findings suggest a new possible pathway for amyloid fibril formation by the N-terminal fragment of apoA-I variants: the amyloidogenic mutations partially destabilize the α-helical structure formed upon association with lipid membranes, resulting in physiologically relevant conformations that allow fibril formation.
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Affiliation(s)
- Chiharu Mizuguchi
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Fuka Ogata
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Shiho Mikawa
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Kohei Tsuji
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Teruhiko Baba
- Research Center for Stem Cell Engineering (SCRC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Akira Shigenaga
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Toshinori Shimanouchi
- Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan
| | - Keiichiro Okuhira
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Akira Otaka
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Hiroyuki Saito
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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16
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Louros NN, Tsiolaki PL, Griffin MDW, Howlett GJ, Hamodrakas SJ, Iconomidou VA. Chameleon 'aggregation-prone' segments of apoA-I: A model of amyloid fibrils formed in apoA-I amyloidosis. Int J Biol Macromol 2015; 79:711-8. [PMID: 26049118 DOI: 10.1016/j.ijbiomac.2015.05.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/20/2015] [Accepted: 05/22/2015] [Indexed: 11/18/2022]
Abstract
Apolipoprotein A-I (apoA-I) is the major component of high density lipoproteins and plays a vital role in reverse cholesterol transport. Lipid-free apoA-I is the main constituent of amyloid deposits found in atherosclerotic plaques, an acquired type of amyloidosis, whereas its N-terminal fragments have been associated with a hereditary form, known as familial apoA-I amyloidosis. Here, we identified and verified four "aggregation-prone" segments of apoA-I with amyloidogenic properties, utilizing electron microscopy, X-ray fiber diffraction, ATR FT-IR spectroscopy and polarized light microscopy. These segments may act as conformational switches, possibly controlling the transition of the α-helical apoA-I content into the "cross-β" architecture of amyloid fibrils. A structural model illuminating the structure of amyloid fibrils formed by the N-terminal fragments of apoA-I is proposed, indicating that two of the identified chameleon segments may play a vital part in the formation of amyloid fibrils in familial apoA-I amyloidosis.
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Affiliation(s)
- Nikolaos N Louros
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens 157 01, Greece
| | - Paraskevi L Tsiolaki
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens 157 01, Greece
| | - Michael D W Griffin
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Geoffrey J Howlett
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Stavros J Hamodrakas
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens 157 01, Greece
| | - Vassiliki A Iconomidou
- Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, Athens 157 01, Greece.
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17
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Structure based aggregation studies reveal the presence of helix-rich intermediate during α-Synuclein aggregation. Sci Rep 2015; 5:9228. [PMID: 25784353 PMCID: PMC4363886 DOI: 10.1038/srep09228] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/13/2015] [Indexed: 12/12/2022] Open
Abstract
Mechanistic understanding of nucleation dependent polymerization by α-synuclein (α-Syn) into toxic oligomers and amyloids is important for the drug development against Parkinson's disease. However the structural and morphological characterization during nucleation and subsequent fibrillation process of α-Syn is not clearly understood. Using a variety of complementary biophysical techniques monitoring entire pathway of nine different synucleins, we found that transition of unstructured conformation into β-sheet rich fibril formation involves helix-rich intermediates. These intermediates are common for all aggregating synucleins, contain high solvent-exposed hydrophobic surfaces, are cytotoxic to SHSY-5Y cells and accelerate α-Syn aggregation efficiently. A multidimensional NMR study characterizing the intermediate accompanied with site-specific fluorescence study suggests that the N-terminal and central portions mainly participate in the helix-rich intermediate formation while the C-terminus remained in an extended conformation. However, significant conformational transitions occur at the middle and at the C-terminus during helix to β-sheet transition as evident from Trp fluorescence study. Since partial helix-rich intermediates were also observed for other amyloidogenic proteins such as Aβ and IAPP, we hypothesize that this class of intermediates may be one of the important intermediates for amyloid formation pathway by many natively unstructured protein/peptides and represent a potential target for drug development against amyloid diseases.
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18
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Chan GKL, Witkowski A, Gantz DL, Zhang TO, Zanni MT, Jayaraman S, Cavigiolio G. Myeloperoxidase-mediated Methionine Oxidation Promotes an Amyloidogenic Outcome for Apolipoprotein A-I. J Biol Chem 2015; 290:10958-71. [PMID: 25759391 DOI: 10.1074/jbc.m114.630442] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Indexed: 11/06/2022] Open
Abstract
High plasma levels of apolipoprotein A-I (apoA-I) correlate with cardiovascular health, whereas dysfunctional apoA-I is a cause of atherosclerosis. In the atherosclerotic plaques, amyloid deposition increases with aging. Notably, apoA-I is the main component of these amyloids. Recent studies identified high levels of oxidized lipid-free apoA-I in atherosclerotic plaques. Likely, myeloperoxidase (MPO) secreted by activated macrophages in atherosclerotic lesions is the promoter of such apoA-I oxidation. We hypothesized that apoA-I oxidation by MPO levels similar to those present in the artery walls in atherosclerosis can promote apoA-I structural changes and amyloid fibril formation. ApoA-I was exposed to exhaustive chemical (H2O2) oxidation or physiological levels of enzymatic (MPO) oxidation and incubated at 37 °C and pH 6.0 to induce fibril formation. Both chemically and enzymatically oxidized apoA-I produced fibrillar amyloids after a few hours of incubation. The amyloid fibrils were composed of full-length apoA-I with differential oxidation of the three methionines. Met to Leu apoA-I variants were used to establish the predominant role of oxidation of Met-86 and Met-148 in the fibril formation process. Importantly, a small amount of preformed apoA-I fibrils was able to seed amyloid formation in oxidized apoA-I at pH 7.0. In contrast to hereditary amyloidosis, wherein specific mutations of apoA-I cause protein destabilization and amyloid deposition, oxidative conditions similar to those promoted by local inflammation in atherosclerosis are sufficient to transform full-length wild-type apoA-I into an amyloidogenic protein. Thus, MPO-mediated oxidation may be implicated in the mechanism that leads to amyloid deposition in the atherosclerotic plaques in vivo.
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Affiliation(s)
- Gary K L Chan
- From the Children's Hospital Oakland Research Institute, Oakland, California 94609
| | - Andrzej Witkowski
- From the Children's Hospital Oakland Research Institute, Oakland, California 94609
| | - Donald L Gantz
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, and
| | - Tianqi O Zhang
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Shobini Jayaraman
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, and
| | - Giorgio Cavigiolio
- From the Children's Hospital Oakland Research Institute, Oakland, California 94609,
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19
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Petrlova J, Dalla-Riva J, Mörgelin M, Lindahl M, Krupinska E, Stenkula KG, Voss JC, Lagerstedt JO. Secondary structure changes in ApoA-I Milano (R173C) are not accompanied by a decrease in protein stability or solubility. PLoS One 2014; 9:e96150. [PMID: 24755625 PMCID: PMC3995965 DOI: 10.1371/journal.pone.0096150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 04/04/2014] [Indexed: 11/29/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) is the main protein of high-density lipoprotein (HDL) and a principal mediator of the reverse cholesterol transfer pathway. Variants of apoA-I have been shown to be associated with hereditary amyloidosis. We previously characterized the G26R and L178H variants that both possess decreased stability and increased fibril formation propensity. Here we investigate the Milano variant of apoAI (R173C; apoAI-M), which despite association with low plasma levels of HDL leads to low prevalence of cardiovascular disease in carriers of this mutation. The R173C substitution is located to a region (residues 170 to 178) that contains several fibrillogenic apoA-I variants, including the L178H variant, and therefore we investigated a potential fibrillogenic property of the apoAI-M protein. Despite the fact that apoAI-M shared several features with the L178H variant regarding increased helical content and low degree of ThT binding during prolonged incubation in physiological buffer, our electron microscopy analysis revealed no formation of fibrils. These results suggest that mutations inducing secondary structural changes may be beneficial in cases where fibril formation does not occur.
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Affiliation(s)
- Jitka Petrlova
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | | | | - Maria Lindahl
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Ewa Krupinska
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Karin G. Stenkula
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - John C. Voss
- School of Medicine, University of California Davis, Davis, California, United States of America
| | - Jens O. Lagerstedt
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail:
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20
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Adachi E, Kosaka A, Tsuji K, Mizuguchi C, Kawashima H, Shigenaga A, Nagao K, Akaji K, Otaka A, Saito H. The extreme N-terminal region of human apolipoprotein A-I has a strong propensity to form amyloid fibrils. FEBS Lett 2013; 588:389-94. [PMID: 24316228 DOI: 10.1016/j.febslet.2013.11.031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/10/2013] [Accepted: 11/25/2013] [Indexed: 02/04/2023]
Abstract
The N-terminal 1-83 residues of apolipoprotein A-I (apoA-I) have a strong propensity to form amyloid fibrils, in which the 46-59 segment was reported to aggregate to form amyloid-like fibrils. In this study, we demonstrated that a fragment peptide comprising the extreme N-terminal 1-43 residues strongly forms amyloid fibrils with a transition to β-sheet-rich structure, and that the G26R point mutation enhances the fibril formation of this segment. Our results suggest that in addition to the 46-59 segment, the extreme N-terminal region plays a crucial role in the development of amyloid fibrils by the N-terminal fragment of amyloidogenic apoA-I variants.
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Affiliation(s)
- Emi Adachi
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Asako Kosaka
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Kohei Tsuji
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Chiharu Mizuguchi
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Hiroyuki Kawashima
- Department of Medicinal Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan
| | - Akira Shigenaga
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Kohjiro Nagao
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Kenichi Akaji
- Department of Medicinal Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan
| | - Akira Otaka
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Hiroyuki Saito
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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21
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Lagerstedt JO, Petrlova J, Hilt S, Marek A, Chung Y, Sriram R, Budamagunta MS, Desreux JF, Thonon D, Jue T, Smirnov AI, Voss JC. EPR assessment of protein sites for incorporation of Gd(III) MRI contrast labels. CONTRAST MEDIA & MOLECULAR IMAGING 2013; 8:252-64. [PMID: 23606429 DOI: 10.1002/cmmi.1518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 10/30/2012] [Accepted: 11/03/2012] [Indexed: 11/06/2022]
Abstract
We have engineered apolipoprotein A-I (apoA-I), a major protein constituent of high-density lipoprotein (HDL), to contain DOTA-chelated Gd(III) as an MRI contrast agent for the purpose of imaging reconstituted HDL (rHDL) biodistribution, metabolism and regulation in vivo. This protein contrast agent was obtained by attaching the thiol-reactive Gd[MTS-ADO3A] label at Cys residues replaced at four distinct positions (52, 55, 76 and 80) in apoA-I. MRI of infused mice previously showed that the Gd-labeled apoA-I migrates to both the liver and the kidney, the organs responsible for HDL catabolism; however, the contrast properties of apoA-I are superior when the ADO3A moiety is located at position 55, compared with the protein labeled at positions 52, 76 or 80. It is shown here that continuous wave X-band (9 GHz) electron paramagnetic resonance (EPR) spectroscopy is capable of detecting differences in the Gd(III) signal when comparing the labeled protein in the lipid-free with the rHDL state. Furthermore, the values of NMR relaxivity obtained for labeled variants in both the lipid-free and rHDL states correlate to the product of the X-band Gd(III) spectral width and the collision frequency between a nitroxide spin label and a polar relaxation agent. Consistent with its superior relaxivity measured by NMR, the rHDL-associated apoA-I containing the Gd[MTS-ADO3A] probe attached to position 55 displays favorable dynamic and water accessibility properties as determined by X-band EPR. While room temperature EPR requires >1 m m Gd(III)-labeled and only >10 µ m nitroxide-labeled protein to resolve the spectrum, the volume requirement is exceptionally low (~5 µl). Thus, X-band EPR provides a practical assessment for the suitability of imaging candidates containing the site-directed ADO3A contrast probe.
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Affiliation(s)
- Jens O Lagerstedt
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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22
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García-González V, Mas-Oliva J. Amyloid fibril formation of peptides derived from the C-terminus of CETP modulated by lipids. Biochem Biophys Res Commun 2013; 434:54-9. [PMID: 23545259 DOI: 10.1016/j.bbrc.2013.03.067] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 03/18/2013] [Indexed: 01/31/2023]
Abstract
Cholesteryl-ester transfer protein (CETP) is a plasmatic protein involved in neutral lipid transfer between lipoproteins. Focusing on the last 12 C-terminus residues we have previously shown that mutation D470N promotes a conformational change towards a β-secondary structure. In turn, this modification leads to the formation of oligomers and fibrillar structures, which cause cytotoxic effects similar to the ones provoked by amyloid peptides. In this study, we evaluated the role of specific lipid arrangements on the structure of peptide helix-Z (D470N) through the use of thioflavin T fluorescence, peptide bond absorbance, circular dichroism and electron microscopy. The results indicate that the use of micelles formed with lysophosphatidylcholine and lysophosphatidic acid (LPA) under neutral pH induce a conformational transition of peptide helix-Z containing a β-sheet conformation to a native α-helix structure, therefore avoiding the formation of amyloid fibrils. In contrast, incubation with phosphatidic acid does not change the profile for the β-sheet conformation. When the electrostatic charge at the surface of micelles or vesicles is regulated through the use of lipids such as phospholipid and LPA, minimal changes and the presence of β-structures were recorded. Mixtures with a positive net charge diminished the percentage of β-structure and the amount of amyloid fibrils. Our results suggest that the degree of solvation determined by the presence of a free hydroxyl group on lipids such as LPA is a key condition that can modulate the secondary structure and the consequent formation of amyloid fibrils in the highly flexible C-terminus domain of CETP.
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Affiliation(s)
- Victor García-González
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, DF, Mexico
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23
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Adachi E, Nakajima H, Mizuguchi C, Dhanasekaran P, Kawashima H, Nagao K, Akaji K, Lund-Katz S, Phillips MC, Saito H. Dual role of an N-terminal amyloidogenic mutation in apolipoprotein A-I: destabilization of helix bundle and enhancement of fibril formation. J Biol Chem 2012; 288:2848-56. [PMID: 23233678 DOI: 10.1074/jbc.m112.428052] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A number of naturally occurring mutations of apolipoprotein (apo) A-I, the major protein of HDL, are known to be associated with hereditary amyloidosis and atherosclerosis. Here, we examined the effects of the G26R point mutation in apoA-I (apoA-I(Iowa)) on the structure, stability, and aggregation propensity to form amyloid fibril of full-length apoA-I and the N-terminal fragment of apoA-I. Circular dichroism and fluorescence measurements demonstrated that the G26R mutation destabilizes the N-terminal helix bundle domain of full-length protein, leading to increased hydrophobic surface exposure, whereas it has no effect on the initial structure of the N-terminal 1-83 fragment, which is predominantly a random coil structure. Upon incubation for extended periods at neutral pH, the N-terminal 1-83 variants undergo a conformational change to β-sheet-rich structure with a great increase in thioflavin T fluorescence, whereas no structural change is observed in full-length proteins. Comparison of fibril-forming propensity among substituted mutants at Gly-26 position of 1-83 fragments demonstrated that the G26R mutation enhances the nucleation step of fibril formation, whereas G26K and G26E mutations have small or inhibiting effects on the formation of fibrils. These fibrils of the 1-83 variants have long and straight morphology as revealed by atomic force microscopy and exhibited significant toxicity with HEK293 cells. Our results indicate dual critical roles of the arginine residue at position 26 in apoA-I(Iowa): destabilization of the N-terminal helix bundle structure in full-length protein and enhancement of amyloid fibril formation by the N-terminal 1-83 fragment.
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Affiliation(s)
- Emi Adachi
- Institute of Health Biosciences and Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan
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24
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Arciello A, De Marco N, Del Giudice R, Guglielmi F, Pucci P, Relini A, Monti DM, Piccoli R. Insights into the fate of the N-terminal amyloidogenic polypeptide of ApoA-I in cultured target cells. J Cell Mol Med 2012; 15:2652-63. [PMID: 21306558 PMCID: PMC4373434 DOI: 10.1111/j.1582-4934.2011.01271.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Apolipoprotein A-I (ApoA-I) is an extracellular lipid acceptor, whose role in cholesterol efflux and high-density lipoprotein formation is mediated by ATP-binding cassette transporter A1 (ABCA1). Nevertheless, some ApoA-I variants are associated to systemic forms of amyloidosis, characterized by extracellular fibril deposition in peripheral organs. Heart amyloid fibrils were found to be mainly constituted by the 93-residue N-terminal fragment of ApoA-I, named [1-93]ApoA-I. In this paper, rat cardiomyoblasts were used as target cells to analyse binding, internalization and intracellular fate of the fibrillogenic polypeptide in comparison to full-length ApoA-I. We provide evidence that the polypeptide: (i) binds to specific sites on cell membrane (K(d) = 5.90 ± 0.70 × 10(-7) M), where it partially co-localizes with ABCA1, as also described for ApoA-I; (ii) is internalized mostly by chlatrin-mediated endocytosis and lipid rafts, whereas ApoA-I is internalized preferentially by chlatrin-coated pits and macropinocytosis and (iii) is rapidly degraded by proteasome and lysosomes, whereas ApoA-I partially co-localizes with recycling endosomes. Vice versa, amyloid fibrils, obtained by in vitro aggregation of [1-93]ApoA-I, were found to be unable to enter the cells. We propose that internalization and intracellular degradation of [1-93]ApoA-I may divert the polypeptide from amyloid fibril formation and contribute to the slow progression and late onset that characterize this pathology.
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Affiliation(s)
- Angela Arciello
- Department of Structural and Functional Biology, University of Naples Federico II, School of Biotechnological Sciences, Naples, Italy
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25
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Ryan TM, Friedhuber A, Lind M, Howlett GJ, Masters C, Roberts BR. Small amphipathic molecules modulate secondary structure and amyloid fibril-forming kinetics of Alzheimer disease peptide Aβ(1-42). J Biol Chem 2012; 287:16947-54. [PMID: 22461629 DOI: 10.1074/jbc.m111.321778] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Amyloid fibril formation is associated with a number of debilitating systemic and neurodegenerative diseases. One of the most prominent is Alzheimer disease in which aggregation and deposition of the Aβ peptide occur. Aβ is widely considered to mediate the extensive neuronal loss observed in this disease through the formation of soluble oligomeric species, with the final fibrillar end product of the aggregation process being relatively inert. Factors that influence the aggregation of these amyloid-forming proteins are therefore very important. We have screened a library of 96 amphipathic molecules for effects on Aβ(1-42) aggregation and self-association. We find, using thioflavin T fluorescence and electron microscopy assays, that 30 of the molecules inhibit the aggregation process, whereas 36 activate fibril formation. Several activators and inhibitors were subjected to further analysis using analytical ultracentrifugation and circular dichroism. Activators typically display a 1:10 peptide:detergent stoichiometry for maximal activation, whereas the inhibitors are effective at a 1:1 stoichiometry. Analytical ultracentrifugation and circular dichroism experiments show that activators promote a mixture of unfolded and β-sheet structures and rapidly form large aggregates, whereas inhibitors induce α-helical structures that form stable dimeric/trimeric oligomers. The results suggest that Aβ(1-42) contains at least one small molecule binding site, which modulates the secondary structure and aggregation processes. Further studies of the binding of these compounds to Aβ may provide insight for developing therapeutic strategies aimed at stabilizing Aβ in a favorable conformation.
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Affiliation(s)
- Timothy M Ryan
- Mental Health Research Institute, the University of Melbourne, Parkville, Victoria 3010, Australia
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26
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Gursky O, Mei X, Atkinson D. The crystal structure of the C-terminal truncated apolipoprotein A-I sheds new light on amyloid formation by the N-terminal fragment. Biochemistry 2011; 51:10-8. [PMID: 22229410 DOI: 10.1021/bi2017014] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apolipoprotein A-I (apoA-I) is the main protein of plasma high-density lipoproteins (HDL, or good cholesterol) that remove excess cell cholesterol and protect against atherosclerosis. In hereditary amyloidosis, mutations in apoA-I promote its proteolysis and the deposition of the 9-11 kDa N-terminal fragments as fibrils in vital organs such as kidney, liver, and heart, causing organ damage. All known amyloidogenic mutations in human apoA-I are clustered in two residue segments, 26-107 and 154-178. The X-ray crystal structure of the C-terminal truncated human protein, Δ(185-243)apoA-I, determined to 2.2 Å resolution by Mei and Atkinson, provides the structural basis for understanding apoA-I destabilization in amyloidosis. The sites of amyloidogenic mutations correspond to key positions within the largely helical four-segment bundle comprised of residues 1-120 and 144-184. Mutations in these positions disrupt the bundle structure and destabilize lipid-free apoA-I, thereby promoting its proteolysis. Moreover, many mutations place a hydrophilic or Pro group in the middle of the hydrophobic lipid-binding face of the amphipathic α-helices, which will likely shift the population distribution from HDL-bound to lipid-poor/free apoA-I that is relatively unstable and labile to proteolysis. Notably, the crystal structure shows segment L44-S55 in an extended conformation consistent with the β-strand-like geometry. Exposure of this segment upon destabilization of the four-segment bundle probably initiates the α-helix to β-sheet conversion in amyloidosis. In summary, we propose that the amyloidogenic mutations promote apoA-I proteolysis by destabilizing the protein structure not only in the lipid-free but also in the HDL-bound form, with segment L44-S55 providing a likely template for the cross-β-sheet conformation.
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Affiliation(s)
- Olga Gursky
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, United States.
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27
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Petrlova J, Duong T, Cochran MC, Axelsson A, Mörgelin M, Roberts LM, Lagerstedt JO. The fibrillogenic L178H variant of apolipoprotein A-I forms helical fibrils. J Lipid Res 2011; 53:390-398. [PMID: 22184756 PMCID: PMC3276462 DOI: 10.1194/jlr.m020883] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
A number of amyloidogenic variants of apoA-I have been discovered but most have not
been analyzed. Previously, we showed that the G26R mutation of apoA-I leads to
increased β-strand structure, increased N-terminal protease susceptibility, and
increased fibril formation after several days of incubation. In vivo, this and other
variants mutated in the N-terminal domain (residues 26 to ∼90) lead to renal and
hepatic accumulation. In contrast, several mutations identified within residues 170
to 178 lead to cardiac, laryngeal, and cutaneous protein deposition. Here, we
describe the structural changes in the fibrillogenic variant L178H. Like G26R, the
initial structure of the protein exhibits altered tertiary conformation relative to
wild-type protein along with decreased stability and an altered lipid binding
profile. However, in contrast to G26R, L178H undergoes an increase in helical
structure upon incubation at 37°C with a half time (t1/2) of about 12
days. Upon prolonged incubation, the L178H mutant forms fibrils of a diameter of 10
nm that ranges in length from 30 to 120 nm. These results show that apoA-I, known for
its dynamic properties, has the ability to form multiple fibrillar conformations,
which may play a role in the tissue-specific deposition of the individual
variants.
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Affiliation(s)
- Jitka Petrlova
- Department of Experimental Medical Sciences, Lund University, S-221 84 Lund, Sweden; and
| | - Trang Duong
- Department of Chemistry, California State University Sacramento, Sacramento, CA 95819
| | - Megan C Cochran
- Department of Chemistry, California State University Sacramento, Sacramento, CA 95819
| | - Annika Axelsson
- Department of Experimental Medical Sciences, Lund University, S-221 84 Lund, Sweden; and
| | - Matthias Mörgelin
- Department of Experimental Medical Sciences, and Department of Infection Medicine, Lund University, S-221 84 Lund, Sweden; and
| | - Linda M Roberts
- Department of Chemistry, California State University Sacramento, Sacramento, CA 95819.
| | - Jens O Lagerstedt
- Department of Experimental Medical Sciences, Lund University, S-221 84 Lund, Sweden; and.
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28
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Ryan TM, Griffin MDW, Bailey MF, Schuck P, Howlett GJ. NBD-labeled phospholipid accelerates apolipoprotein C-II amyloid fibril formation but is not incorporated into mature fibrils. Biochemistry 2011; 50:9579-86. [PMID: 21985034 DOI: 10.1021/bi201192r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human apolipoprotein (apo) C-II is one of several lipid-binding proteins that self-assemble into fibrils and accumulate in disease-related amyloid deposits. A general characteristic of these amyloid deposits is the presence of lipids, known to modulate individual steps in amyloid fibril formation. ApoC-II fibril formation is activated by submicellar phospholipids but inhibited by micellar lipids. We examined the mechanism for the activation by submicellar lipids using the fluorescently labeled, short-chain phospholipid 1-dodecyl-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]-2-hydroxyglycero-3-phosphocholine (NBD-lyso-12-PC). Addition of submicellar NBD-lyso-12-PC increased the rate of fibril formation by apoC-II approximately 2-fold. Stopped flow kinetic analysis using fluorescence detection and low, non-fibril-forming concentrations of apoC-II indicated NBD-lyso-12-PC binds rapidly, on the millisecond time scale, followed by the slower formation of discrete apoC-II tetramers. Sedimentation velocity analysis showed NBD-lyso-12-PC binds to both apoC-II monomers and tetramers at approximately five sites per monomer with an average dissociation constant of approximately 10 μM. Mature apoC-II fibrils formed in the presence of NBD-lyso-12-PC were devoid of lipid, indicating a purely catalytic role for submicellar lipids in the activation of apoC-II fibril formation. These studies demonstrate the catalytic potential of small amphiphilic molecules in controlling protein folding and fibril assembly pathways.
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Affiliation(s)
- Timothy M Ryan
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria 3010, Australia
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29
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Abstract
Amyloidosis is caused by extracellular deposition of proteins in an insoluble manner within tissues. In hereditary forms of amyloidosis, transthyretin, fibrinogen A-α, lysozyme, gelsolin, apolipoprotein A-I, and A-II accumulate in the tissue plaques. Here we describe a 52-year-old man with no family history of renal disease who presented with increased urinary frequency, gradual loss of renal function but no significant proteinuria. Renal biopsy found large amounts of amyloid restricted to the medulla with no involvement of glomeruli or vessels. Immunohistochemical analysis for transthyretin or serum amyloid A and tests for an underlying monoclonal gammopathy were negative. Although initially suspected to be amyloid light chain amyloidosis, laser microdissection and mass spectrometry showed that the amyloid was composed of large amounts of apolipoprotein A-IV. This was based on mass spectrometry studies that showed 100, 96, and 73 spectra in three microdissected samples that matched to apolipoprotein A-IV with 100% probability. DNA analyses detected three sequence variants representing common polymorphisms of the apolipoprotein A-IV gene. Thus, in this case, apolipoprotein A-IV deposition and renal involvement appear to be restricted to the medulla. A high degree of suspicion is required for the diagnosis of apolipoprotein A-IV amyloidosis as it may be missed if a renal biopsy consists only of cortex.
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30
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Ramella NA, Rimoldi OJ, Prieto ED, Schinella GR, Sanchez SA, Jaureguiberry MS, Vela ME, Ferreira ST, Tricerri MA. Human apolipoprotein A-I-derived amyloid: its association with atherosclerosis. PLoS One 2011; 6:e22532. [PMID: 21811627 PMCID: PMC3139661 DOI: 10.1371/journal.pone.0022532] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 06/23/2011] [Indexed: 01/08/2023] Open
Abstract
Amyloidoses constitute a group of diseases in which soluble proteins aggregate and deposit extracellularly in tissues. Nonhereditary apolipoprotein A-I (apoA-I) amyloid is characterized by deposits of nonvariant protein in atherosclerotic arteries. Despite being common, little is known about the pathogenesis and significance of apoA-I deposition. In this work we investigated by fluorescence and biochemical approaches the impact of a cellular microenvironment associated with chronic inflammation on the folding and pro-amyloidogenic processing of apoA-I. Results showed that mildly acidic pH promotes misfolding, aggregation, and increased binding of apoA-I to extracellular matrix elements, thus favoring protein deposition as amyloid like-complexes. In addition, activated neutrophils and oxidative/proteolytic cleavage of the protein give rise to pro amyloidogenic products. We conclude that, even though apoA-I is not inherently amyloidogenic, it may produce non hereditary amyloidosis as a consequence of the pro-inflammatory microenvironment associated to atherogenesis.
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Affiliation(s)
- Nahuel A. Ramella
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT-CONICET, La Plata, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Omar J. Rimoldi
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT-CONICET, La Plata, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Eduardo D. Prieto
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT-CONICET, La Plata, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Guillermo R. Schinella
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Susana A. Sanchez
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, California, United States of America
- Microscopy Unit, Fundación CNIC-Carlos III, Centro Nacional de Investigaciones Cardiovasculares, Madrid, España
| | - María S. Jaureguiberry
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT-CONICET, La Plata, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - María E. Vela
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CCT-CONICET, La Plata, Argentina
| | - Sergio T. Ferreira
- Program in Biochemistry and Cellular Biophysics, Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - M. Alejandra Tricerri
- Instituto de Investigaciones Bioquímicas La Plata (INIBIOLP), CCT-CONICET, La Plata, Argentina
- Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
- * E-mail:
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31
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Raimondi S, Guglielmi F, Giorgetti S, Gaetano SD, Arciello A, Monti DM, Relini A, Nichino D, Doglia SM, Natalello A, Pucci P, Mangione P, Obici L, Merlini G, Stoppini M, Robustelli P, Tartaglia GG, Vendruscolo M, Dobson CM, Piccoli R, Bellotti V. Effects of the Known Pathogenic Mutations on the Aggregation Pathway of the Amyloidogenic Peptide of Apolipoprotein A-I. J Mol Biol 2011; 407:465-76. [DOI: 10.1016/j.jmb.2011.01.044] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 12/22/2010] [Accepted: 01/23/2011] [Indexed: 11/30/2022]
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32
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Teoh CL, Griffin MDW, Howlett GJ. Apolipoproteins and amyloid fibril formation in atherosclerosis. Protein Cell 2011; 2:116-27. [PMID: 21400045 DOI: 10.1007/s13238-011-1013-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 01/29/2011] [Indexed: 10/18/2022] Open
Abstract
Amyloid fibrils arise from the aggregation of misfolded proteins into highly-ordered structures. The accumulation of these fibrils along with some non-fibrillar constituents within amyloid plaques is associated with the pathogenesis of several human degenerative diseases. A number of plasma apolipoproteins, including apolipoprotein (apo) A-I, apoA-II, apoC-II and apoE are implicated in amyloid formation or influence amyloid formation by other proteins. We review present knowledge of amyloid formation by apolipoproteins in disease, with particular focus on atherosclerosis. Further insights into the molecular mechanisms underlying their amyloidogenic propensity are obtained from in vitro studies which describe factors affecting apolipoprotein amyloid fibril formation and interactions. Additionally, we outline the evidence that amyloid fibril formation by apolipoproteins might play a role in the development and progression of atherosclerosis, and highlight possible molecular mechanisms that could contribute to the pathogenesis of this disease.
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Affiliation(s)
- Chai Lean Teoh
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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33
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High-affinity amphipathic modulators of amyloid fibril nucleation and elongation. J Mol Biol 2010; 406:416-29. [PMID: 21185302 DOI: 10.1016/j.jmb.2010.12.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/15/2010] [Accepted: 12/15/2010] [Indexed: 11/21/2022]
Abstract
The misfolding and aggregation of proteins to form amyloid fibrils are associated with a number of debilitating, age-related diseases. Many of the proteins that form amyloid in vivo are lipid-binding proteins, accounting for the significant impact of lipids on the rate of formation and morphology of amyloid fibrils. To systematically investigate the effect of lipid-like compounds, we screened a range of amphipathic lipids and detergents for their effect on amyloid fibril formation by human apolipoprotein (apo) C-II. The initial screen, conducted using a set of amphiphiles at half critical micelle concentration, identified several activators and inhibitors that were selected for further analysis. Sedimentation analysis and circular dichroism studies of apoC-II at low, non-fibril-forming concentrations (0.05 mg/ml) revealed that all of the inhibitors induced the formation of apoC-II dimers enriched in α-helical content while the activators promoted the formation of stable apoC-II tetramers with increased β-structure. Kinetic analysis identified modulators of apoC-II fibril formation that were effective at concentrations as low as 10 μM, corresponding to a modulator-to-apoC-II ratio of approximately 1:10. Delayed addition of the test compounds after fibril formation had commenced allowed the effects of selected amphiphiles on fibril elongation to be determined separately from their effects on fibril nucleation. The results indicated that specific amphiphiles induce structural changes in apoC-II that cause separate and independent effects on fibril nucleation and elongation. Low-molecular-weight amphipathic lipids and detergents may serve as useful, stage-specific modulators of protein self-assembly and fibril formation in disease-prevention strategies.
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34
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Singh Y, Sharpe PC, Hoang HN, Lucke AJ, McDowall AW, Bottomley SP, Fairlie DP. Amyloid Formation from an α-Helix Peptide Bundle Is Seeded by 310-Helix Aggregates. Chemistry 2010; 17:151-60. [DOI: 10.1002/chem.201002500] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Indexed: 11/08/2022]
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35
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Weers PMM, Patel AB, Wan LCP, Guigard E, Kay CM, Hafiane A, McPherson R, Marcel YL, Kiss RS. Novel N-terminal mutation of human apolipoprotein A-I reduces self-association and impairs LCAT activation. J Lipid Res 2010; 52:35-44. [PMID: 20884842 PMCID: PMC2999918 DOI: 10.1194/jlr.m007500] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We have identified a novel mutation in apoA-I (serine 36 to alanine; S36A) in a human subject with severe hypoalphalipoproteinemia. The mutation is located in the N-terminal region of the protein, which has been implicated in several functions, including lipid binding and lecithin:cholesterol acyltransferase (LCAT) activity. In the present study, the S36A protein was produced recombinantly and characterized both structurally and functionally. While the helical content of the mutant protein was lower compared with wild-type (WT) apoA-I, it retained its helical character. The protein stability, measured as the resistance to guanidine-induced denaturation, decreased significantly. Interestingly, native gel electrophoresis, cross-linking, and sedimentation equilibrium analysis showed that the S36A mutant was primarily present as a monomer, notably different from the WT protein, which showed considerable oligomeric forms. Although the ability of S36A apoA-I to solubilize phosphatidylcholine vesicles and bind to lipoprotein surfaces was not altered, a significantly impaired LCAT activation compared with the WT protein was observed. These results implicate a region around S36 in apoA-I self-association, independent of the intact C terminus. Furthermore, the region around S36 in the N-terminus of human apoA-I is necessary for LCAT activation.
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Affiliation(s)
- Paul M M Weers
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA, USA
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36
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Vijayan R, Biggin PC. Conformational preferences of a 14-residue fibrillogenic peptide from acetylcholinesterase. Biochemistry 2010; 49:3678-84. [PMID: 20356043 PMCID: PMC2860372 DOI: 10.1021/bi1001807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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A 14-residue fragment from near the C-terminus of the enzyme acetylcholinesterase (AChE) is believed to have a neurotoxic/neurotrophic effect acting via an unknown pathway. While the peptide is α-helical in the full-length enzyme, the structure and association mechanism of the fragment are unknown. Using multiple molecular dynamics simulations, starting from a tetrameric complex of the association domain of AChE and systematically disassembled subsets that include the peptide fragment, we show that the fragment is incapable of retaining its helicity in solution. Extensive replica exchange Monte Carlo folding and unfolding simulations in implicit solvent with capped and uncapped termini failed to converge to any consistent cluster of structures, suggesting that the fragment remains largely unstructured in solution under the conditions considered. Furthermore, extended molecular dynamics simulations of two steric zipper models show that the peptide is likely to form a zipper with antiparallel sheets and that peptides with mutations known to prevent fibril formation likely do so by interfering with this packing. The results demonstrate how the local environment of a peptide can stabilize a particular conformation.
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Affiliation(s)
- Ranjit Vijayan
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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37
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Monti DM, Guglielmi F, Monti M, Cozzolino F, Torrassa S, Relini A, Pucci P, Arciello A, Piccoli R. Effects of a lipid environment on the fibrillogenic pathway of the N-terminal polypeptide of human apolipoprotein A-I, responsible for in vivo amyloid fibril formation. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 39:1289-99. [PMID: 20182709 DOI: 10.1007/s00249-010-0582-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/14/2009] [Accepted: 02/04/2010] [Indexed: 11/25/2022]
Abstract
In amyloidosis associated with apolipoprotein A-I (ApoA-I), heart amyloid deposits are mainly constituted by the 93-residue ApoA-I N-terminal region. A recombinant form of the amyloidogenic polypeptide, named [1-93]ApoA-I, shares conformational properties and aggregation propensity with its natural counterpart. The polypeptide, predominantly in a random coil state at pH 8.0, following acidification to pH 4.0 adopts a helical/molten globule transient state, which leads to formation of aggregates. Here we provide evidence that fibrillogenesis occurs also in physiologic-like conditions. At pH 6.4, [1-93]ApoA-I was found to assume predominantly an alpha-helical state, which undergoes aggregation at 37 degrees C over time at a lower rate than at pH 4.0. After 7 days at pH 6.4, protofibrils were observed by atomic force microscopy (AFM). Using a multidisciplinary approach, including circular dichroism (CD), fluorescence, electrophoretic, and AFM analyses, we investigated the effects of a lipid environment on the conformational state and aggregation propensity of [1-93]ApoA-I. Following addition of the lipid-mimicking detergent Triton X-100, the polypeptide was found to be in a helical state at both pH 8.0 and 6.4, with no conformational transition occurring upon acidification. These helical conformers are stable and do not generate aggregated species, as observed by AFM after 21 days. Similarly, analyses of the effects of cholesterol demonstrated that this natural ApoA-I ligand induces formation of alpha-helix at physiological concentrations at both pH 8.0 and 6.4. Zwitterionic, positively charged, and negatively charged liposomes were found to affect [1-93]ApoA-I conformation, inducing helical species. Our data support the idea that lipids play a key role in [1-93]ApoA-I aggregation in vivo.
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Affiliation(s)
- Daria Maria Monti
- Department of Structural and Functional Biology, University of Naples Federico II, Italy
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38
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Methionine oxidation induces amyloid fibril formation by full-length apolipoprotein A-I. Proc Natl Acad Sci U S A 2010; 107:1977-82. [PMID: 20133843 DOI: 10.1073/pnas.0910136107] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Apolipoprotein A-I (apoA-I) is the major protein component of HDL, where it plays an important role in cholesterol transport. The deposition of apoA-I derived amyloid is associated with various hereditary systemic amyloidoses and atherosclerosis; however, very little is known about the mechanism of apoA-I amyloid formation. Methionine residues in apoA-I are oxidized via several mechanisms in vivo to form methionine sulfoxide (MetO), and significant levels of methionine oxidized apoA-I (MetO-apoA-I) are present in normal human serum. We investigated the effect of methionine oxidation on the structure, stability, and aggregation of full-length, lipid-free apoA-I. Circular dichrosim spectroscopy showed that oxidation of all three methionine residues in apoA-I caused partial unfolding of the protein and decreased its thermal stability, reducing the melting temperature (T(m)) from 58.7 degrees C for native apoA-I to 48.2 degrees C for MetO-apoA-I. Analytical ultracentrifugation revealed that methionine oxidation inhibited the native self association of apoA-I to form dimers and tetramers. Incubation of MetO-apoA-I for extended periods resulted in aggregation of the protein, and these aggregates bound Thioflavin T and Congo Red. Inspection of the aggregates by electron microscopy revealed fibrillar structures with a ribbon-like morphology, widths of approximately 11 nm, and lengths of up to several microns. X-ray fibre diffraction studies of the fibrils revealed a diffraction pattern with orthogonal peaks at spacings of 4.64 A and 9.92 A, indicating a cross-beta amyloid structure. This systematic study of fibril formation by full-length apoA-I represents the first demonstration that methionine oxidation can induce amyloid fibril formation.
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39
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Amyloid fibrils formed by selective N-, C-terminal sequences of mouse apolipoprotein A-II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1517-29. [DOI: 10.1016/j.bbapap.2009.06.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 06/02/2009] [Accepted: 06/26/2009] [Indexed: 11/19/2022]
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40
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Disorder-to-order conformational transitions in protein structure and its relationship to disease. Mol Cell Biochem 2009; 330:105-20. [PMID: 19357935 DOI: 10.1007/s11010-009-0105-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 03/30/2009] [Indexed: 01/22/2023]
Abstract
Function in proteins largely depends on the acquisition of specific structures through folding at physiological time scales. Under both equilibrium and non-equilibrium states, proteins develop partially structured molecules that being intermediates in the process, usually resemble the structure of the fully folded protein. These intermediates, known as molten globules, present the faculty of adopting a large variety of conformations mainly supported by changes in their side chains. Taking into account that the mechanism to obtain a fully packed structure is considered more difficult energetically than forming partially "disordered" folding intermediates, evolution might have conferred upon an important number of proteins the capability to first partially fold and-depending on the presence of specific partner ligands-switch on disorder-to-order transitions to adopt a highly ordered well-folded state and reach the lowest energy conformation possible. Disorder in this context can represent segments of proteins or complete proteins that might exist in the native state. Moreover, because this type of disorder-to-order transition in proteins has been found to be reversible, it has been frequently associated with important signaling events in the cell. Due to the central role of this phenomenon in cell biology, protein misfolding and aberrant disorder-to-order transitions have been at present associated with an important number of diseases.
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41
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42
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Ookoshi T, Hasegawa K, Ohhashi Y, Kimura H, Takahashi N, Yoshida H, Miyazaki R, Goto Y, Naiki H. Lysophospholipids induce the nucleation and extension of 2-microglobulin-related amyloid fibrils at a neutral pH. Nephrol Dial Transplant 2008; 23:3247-55. [DOI: 10.1093/ndt/gfn231] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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43
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Mok H, Kim HJ, Park TG. Dissolution of biomacromolecules in organic solvents by nano-complexing with poly(ethylene glycol). Int J Pharm 2008; 356:306-13. [DOI: 10.1016/j.ijpharm.2008.01.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 01/03/2008] [Accepted: 01/04/2008] [Indexed: 01/03/2023]
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44
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Jahn TR, Tennent GA, Radford SE. A common beta-sheet architecture underlies in vitro and in vivo beta2-microglobulin amyloid fibrils. J Biol Chem 2008; 283:17279-86. [PMID: 18424782 PMCID: PMC2427364 DOI: 10.1074/jbc.m710351200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Misfolding and aggregation of normally soluble proteins into amyloid fibrils and their deposition and accumulation underlies a variety of clinically significant diseases. Fibrillar aggregates with amyloid-like properties can also be generated in vitro from pure proteins and peptides, including those not known to be associated with amyloidosis. Whereas biophysical studies of amyloid-like fibrils formed in vitro have provided important insights into the molecular mechanisms of amyloid generation and the structural properties of the fibrils formed, amyloidogenic proteins are typically exposed to mild or more extreme denaturing conditions to induce rapid fibril formation in vitro. Whether the structure of the resulting assemblies is representative of their natural in vivo counterparts, thus, remains a fundamental unresolved issue. Here we show using Fourier transform infrared spectroscopy that amyloid-like fibrils formed in vitro from natively folded or unfolded β2-microglobulin (the protein associated with dialysis-related amyloidosis) adopt an identical β-sheet architecture. The same β-strand signature is observed whether fibril formation in vitro occurs spontaneously or from seeded reactions. Comparison of these spectra with those of amyloid fibrils extracted from patients with dialysis-related amyloidosis revealed an identical amide I′ absorbance maximum, suggestive of a characteristic and conserved amyloid fold. Our results endorse the relevance of biophysical studies for the investigation of the molecular mechanisms of β2-microglobulin fibrillogenesis, knowledge about which may inform understanding of the pathobiology of this protein.
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Affiliation(s)
- Thomas R Jahn
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
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45
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Harrison RS, Sharpe PC, Singh Y, Fairlie DP. Amyloid peptides and proteins in review. Rev Physiol Biochem Pharmacol 2007; 159:1-77. [PMID: 17846922 DOI: 10.1007/112_2007_0701] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Amyloids are filamentous protein deposits ranging in size from nanometres to microns and composed of aggregated peptide beta-sheets formed from parallel or anti-parallel alignments of peptide beta-strands. Amyloid-forming proteins have attracted a great deal of recent attention because of their association with over 30 diseases, notably neurodegenerative conditions like Alzheimer's, Huntington's, Parkinson's, Creutzfeldt-Jacob and prion disorders, but also systemic diseases such as amyotrophic lateral sclerosis (Lou Gehrig's disease) and type II diabetes. These diseases are all thought to involve important conformational changes in proteins, sometimes termed misfolding, that usually produce beta-sheet structures with a strong tendency to aggregate into water-insoluble fibrous polymers. Reasons for such conformational changes in vivo are still unclear. Intermediate aggregated state(s), rather than precipitated insoluble polymeric aggregates, have recently been implicated in cellular toxicity and may be the source of aberrant pathology in amyloid diseases. Numerous in vitro studies of short and medium length peptides that form amyloids have provided some clues to amyloid formation, with an alpha-helix to beta-sheet folding transition sometimes implicated as an intermediary step leading to amyloid formation. More recently, quite a few non-pathological amyloidogenic proteins have also been identified and physiological properties have been ascribed, challenging previous implications that amyloids were always disease causing. This article summarises a great deal of current knowledge on the occurrence, structure, folding pathways, chemistry and biology associated with amyloidogenic peptides and proteins and highlights some key factors that have been found to influence amyloidogenesis.
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Affiliation(s)
- R S Harrison
- Centre for Drug Design and Development, Institute for Molecular Bioscience, University of Queensland, QLD 4072, Brisbane, Australia
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Munishkina LA, Fink AL. Fluorescence as a method to reveal structures and membrane-interactions of amyloidogenic proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1862-85. [PMID: 17493579 DOI: 10.1016/j.bbamem.2007.03.015] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Revised: 03/11/2007] [Accepted: 03/13/2007] [Indexed: 10/23/2022]
Abstract
Amyloidogenesis is a characteristic feature of the 40 or so known protein deposition diseases, and accumulating evidence strongly suggests that self-association of misfolded proteins into either fibrils, protofibrils, or soluble oligomeric species is cytotoxic. The most likely mechanism for toxicity is through perturbation of membrane structure, leading to increased membrane permeability and eventual cell death. There have been a rather limited number of investigations of the interactions of amyloidogenic polypeptides and their aggregated states with membranes; these are briefly reviewed here. Amyloidogenic proteins discussed include A-beta from Alzheimer's disease, the prion protein, alpha-synuclein from Parkinson's disease, transthyretin (FAP, SSA amyloidosis), immunoglobulin light chains (primary (AL) amyloidosis), serum amyloid A (secondary (AA) amyloidosis), amylin or IAPP (Type 2 diabetes) and apolipoproteins. This review highlights the significant role played by fluorescence techniques in unraveling the nature of amyloid fibrils and their interactions and effects on membranes. Fluorescence spectroscopy is a valuable and versatile method for studying the complex mechanisms of protein aggregation, amyloid fibril formation and the interactions of amyloidogenic proteins with membranes. Commonly used fluorescent techniques include intrinsic and extrinsic fluorophores, fluorescent probes incorporated in the membrane, steady-state and lifetime measurements of fluorescence emission, fluorescence correlation spectroscopy, fluorescence anisotropy and polarization, fluorescence resonance energy transfer (FRET), fluorescence quenching, and fluorescence microscopy.
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Affiliation(s)
- Larissa A Munishkina
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
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Lagerstedt JO, Cavigiolio G, Roberts LM, Hong HS, Jin LW, Fitzgerald P, Oda MN, Voss JC. Mapping the structural transition in an amyloidogenic apolipoprotein A-I. Biochemistry 2007; 46:9693-9. [PMID: 17665932 PMCID: PMC3650831 DOI: 10.1021/bi7005493] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The single amino acid mutation G26R in human apolipoprotein A-I (apoA-IIOWA) leads to the formation of beta-secondary structure rich amyloid fibrils in vivo. Here we show that full-length apoA-IIOWA has a decreased lipid-binding capability, an increased amino-terminal sensitivity to protease, and a propensity to form annular protofibrils visible by electron microscopy. The molecular basis for the conversion of apolipoprotein A-I to a proamyloidogenic form was examined by electron paramagnetic resonance spectroscopy. Our recent findings [Lagerstedt, J. O., Budamagunta, M. S., Oda, M. N., and Voss, J. C. (2007) J. Biol. Chem. 282, 9143-9149] indicate that Gly26 in the native apoprotein separates a preceding beta-strand structure (residues 20-25) from a downstream largely alpha-helical region. The current study demonstrates that the G26R variant promotes a structural transition of positions 27-56 to a mixture of coil and beta-strand secondary structure. Microscopy and staining by amyloidophilic dyes suggest that this alteration extends throughout the protein within 1 week of incubation in vitro, leading to insoluble aggregates of distinct morphology. The severe consequences of the Iowa mutation likely arise from the combination of losing the contribution of the native Gly residue in terminating beta-strand propagation and the promotion of beta-structure when an Arg is introduced adjacent to the succeeding residue of identical charge and size, Arg27.
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Affiliation(s)
- Jens O. Lagerstedt
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA 95616
- Department of Internal Medicine, University of California, Davis, CA 95616
| | - Giorgio Cavigiolio
- Department of Cell Biology and Human Anatomy, University of California, Davis, CA 95616
| | - Linda M. Roberts
- Department of Chemistry California State University, Sacramento, CA 95819
| | - Hyun-Seok Hong
- Department of Pathology, University of California, Davis, CA 95616
| | - Lee-Way Jin
- Department of Pathology, University of California, Davis, CA 95616
| | - Paul Fitzgerald
- Department of Cell Biology and Human Anatomy, University of California, Davis, CA 95616
| | - Michael N. Oda
- Children’s Hospital Oakland Research Institute, Oakland, CA 94609
| | - John C. Voss
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA 95616
- Corresponding author: Tel: +1 530 754 7583; Fax: +1 530 752 3516;
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48
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Lagerstedt JO, Budamagunta MS, Oda MN, Voss JC. Electron paramagnetic resonance spectroscopy of site-directed spin labels reveals the structural heterogeneity in the N-terminal domain of apoA-I in solution. J Biol Chem 2007; 282:9143-9. [PMID: 17204472 DOI: 10.1074/jbc.m608717200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) is the major protein constituent of high density lipoprotein (HDL) and plays a central role in phospholipid and cholesterol metabolism. This 243-residue long protein is remarkably flexible and assumes numerous lipid-dependent conformations. Consequently, definitive structural determination of lipid-free apoA-I in solution has been difficult. Using electron paramagnetic spectroscopy of site-directed spin labels in the N-terminal domain of apoA-I (residues 1-98) we have mapped a mixture of secondary structural elements, the composition of which is consistent with findings from other in-solution methods. Based on side chain mobility and their accessibility to polar and non-polar spin relaxers, the precise location of secondary elements for amino acids 14-98 was determined for both lipid-free and lipid-bound apoA-I. Based on intermolecular dipolar coupling at positions 26, 44, and 64, these secondary structural elements were arranged into a tertiary fold to generate a structural model for lipid-free apoA-I in solution.
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Affiliation(s)
- Jens O Lagerstedt
- Department of Biochemistry, University of California, Davis, California 95616, USA
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49
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Wilson LM, Mok YF, Binger KJ, Griffin MDW, Mertens HDT, Lin F, Wade JD, Gooley PR, Howlett GJ. A structural core within apolipoprotein C-II amyloid fibrils identified using hydrogen exchange and proteolysis. J Mol Biol 2006; 366:1639-51. [PMID: 17217959 DOI: 10.1016/j.jmb.2006.12.040] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 12/04/2006] [Accepted: 12/15/2006] [Indexed: 11/21/2022]
Abstract
Plasma apolipoproteins show alpha-helical structure in the lipid-bound state and limited conformational stability in the absence of lipid. This structural instability of lipid-free apolipoproteins may account for the high propensity of apolipoproteins to aggregate and accumulate in disease-related amyloid deposits. Here, we explore the properties of amyloid fibrils formed by apolipoproteins using human apolipoprotein (apo) C-II as a model system. Hydrogen-deuterium exchange and NMR spectroscopy of apoC-II fibrils revealed core regions between residues 19-37 and 57-74 with reduced amide proton exchange rates compared to monomeric apoC-II. The C-terminal core region was also identified by partial proteolysis of apoC-II amyloid fibrils using endoproteinase GluC and proteinase K. Complete tryptic hydrolysis of apoC-II fibrils followed by centrifugation yielded a single peptide in the pellet fraction identified using mass spectrometry as apoC-II(56-76). Synthetic apoC-II(56-76) readily formed fibrils, albeit with a different morphology and thioflavinT fluorescence yield compared to full-length apoC-II. Studies with smaller peptides narrowed this fibril-forming core to a region within residues 60-70. We postulate that the ability of apoC-II(60-70) to independently form amyloid fibrils drives fibril formation by apoC-II. These specific amyloid-forming regions within apolipoproteins may underlie the propensity of apolipoproteins and their peptide derivatives to accumulate in amyloid deposits in vivo.
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Affiliation(s)
- Leanne M Wilson
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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50
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Di Gaetano S, Guglielmi F, Arciello A, Mangione P, Monti M, Pagnozzi D, Raimondi S, Giorgetti S, Orrù S, Canale C, Pucci P, Dobson CM, Bellotti V, Piccoli R. Recombinant amyloidogenic domain of ApoA-I: analysis of its fibrillogenic potential. Biochem Biophys Res Commun 2006; 351:223-8. [PMID: 17056013 DOI: 10.1016/j.bbrc.2006.10.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Accepted: 10/06/2006] [Indexed: 05/12/2023]
Abstract
A variety of amyloid diseases are associated with fibrillar aggregates from N-terminal fragments of ApoA-I generated through a largely unexplored multi-step process. The understanding of the molecular mechanism is impaired by the lack of suitable amounts of the fibrillogenic polypeptides that could not be produced by recombinant methods so far. We report the production and the conformational analysis of recombinant ApoA-I 1-93 fragment. Similarly to the polypeptide isolated ex vivo, a pH switch from 7 to 4 induces a fast and reversible conformational transition to a helical state and leads to the identification of a key intermediate in the fibrillogenesis process. Limited proteolysis experiments suggested that the C-terminal region is involved in helix formation. The recombinant polypeptide generates fibrils at pH 4 on a time scale comparable with that of the native fragment. These findings open the way to studies on structural, thermodynamic, and kinetic aspects of ApoA-I fibrillogenesis.
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Affiliation(s)
- Sonia Di Gaetano
- Istituto di Biostrutture e Bioimmagini, CNR, Napoli 80134, Italy
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