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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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Guo J, Chen S, Zhang Y, Liu J, Jiang L, Hu L, Yao K, Yu Y, Chen X. Cholesterol metabolism: physiological regulation and diseases. MedComm (Beijing) 2024; 5:e476. [PMID: 38405060 PMCID: PMC10893558 DOI: 10.1002/mco2.476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 02/27/2024] Open
Abstract
Cholesterol homeostasis is crucial for cellular and systemic function. The disorder of cholesterol metabolism not only accelerates the onset of cardiovascular disease (CVD) but is also the fundamental cause of other ailments. The regulation of cholesterol metabolism in the human is an extremely complex process. Due to the dynamic balance between cholesterol synthesis, intake, efflux and storage, cholesterol metabolism generally remains secure. Disruption of any of these links is likely to have adverse effects on the body. At present, increasing evidence suggests that abnormal cholesterol metabolism is closely related to various systemic diseases. However, the exact mechanism by which cholesterol metabolism contributes to disease pathogenesis remains unclear, and there are still unknown factors. In this review, we outline the metabolic process of cholesterol in the human body, especially reverse cholesterol transport (RCT). Then, we discuss separately the impact of abnormal cholesterol metabolism on common diseases and potential therapeutic targets for each disease, including CVD, tumors, neurological diseases, and immune system diseases. At the end of this review, we focus on the effect of cholesterol metabolism on eye diseases. In short, we hope to provide more new ideas for the pathogenesis and treatment of diseases from the perspective of cholesterol.
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Affiliation(s)
- Jiarui Guo
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Silong Chen
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Ying Zhang
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
- Institute of Translational MedicineZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Jinxia Liu
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Luyang Jiang
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Lidan Hu
- National Clinical Research Center for Child HealthThe Children's HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Ke Yao
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Yibo Yu
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
| | - Xiangjun Chen
- Eye Center of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
- Institute of Translational MedicineZhejiang University School of MedicineHangzhouZhejiang ProvinceChina
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3
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Stankov S, Vitali C, Park J, Nguyen D, Mayne L, Englander SW, Levin MG, Vujkovic M, Hand NJ, Phillips MC, Rader DJ. Comparison of the structure-function properties of wild-type human apoA-V and a C-terminal truncation associated with elevated plasma triglycerides. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.02.21.23286268. [PMID: 36865344 PMCID: PMC9980232 DOI: 10.1101/2023.02.21.23286268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Background Plasma triglycerides (TGs) are causally associated with coronary artery disease and acute pancreatitis. Apolipoprotein A-V (apoA-V, gene APOA5) is a liver-secreted protein that is carried on triglyceride-rich lipoproteins and promotes the enzymatic activity of lipoprotein lipase (LPL), thereby reducing TG levels. Little is known about apoA-V structure-function; naturally occurring human APOA5 variants can provide novel insights. Methods We used hydrogen-deuterium exchange mass spectrometry to determine the secondary structure of human apoA-V in lipid-free and lipid-associated conditions and identified a C-terminal hydrophobic face. Then, we used genomic data in the Penn Medicine Biobank to identify a rare variant, Q252X, predicted to specifically eliminate this region. We interrogated the function of apoA-V Q252X using recombinant protein in vitro and in vivo in apoa5 knockout mice. Results Human apoA-V Q252X carriers exhibited elevated plasma TG levels consistent with loss of function. Apoa5 knockout mice injected with AAV vectors expressing wildtype and variant APOA5-AAV recapitulated this phenotype. Part of the loss of function is due to reduced mRNA expression. Functionally, recombinant apoA-V Q252X was more readily soluble in aqueous solutions and more exchangeable with lipoproteins than WT apoA-V. Despite lacking the C-terminal hydrophobic region (a putative lipid binding domain) this protein also decreased plasma TG in vivo. Conclusions Deletion of apoA-V's C-terminus leads to reduced apoA-V bioavailability in vivo and higher TG levels. However, the C-terminus is not required for lipoprotein binding or enhancement of intravascular lipolytic activity. WT apoA-V is highly prone to aggregation, and this property is markedly reduced in recombinant apoA-V lacking the C-terminus.
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Affiliation(s)
- Sylvia Stankov
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cecilia Vitali
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph Park
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David Nguyen
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Leland Mayne
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - S. Walter Englander
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Michael G. Levin
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA
| | - Marijana Vujkovic
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA
| | - Nicholas J. Hand
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael C. Phillips
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel J. Rader
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Burdick JP, Basi RS, Burns KS, Weers PMM. The role of C-terminal ionic residues in self-association of apolipoprotein A-I. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184098. [PMID: 36481181 DOI: 10.1016/j.bbamem.2022.184098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/15/2022] [Accepted: 11/27/2022] [Indexed: 12/12/2022]
Abstract
Apolipoprotein A-I (apoA-I) is the main protein of high-density lipoprotein and is comprised of a helical bundle domain and a C-terminal (CT) domain encompassing the last ~65 amino acid residues of the 243-residue protein. The CT domain contains three putative helices (helix 8, 9, and 10) and is critical for initiating lipid binding and harbors sites that mediate self-association of the lipid-free protein. Three lysine residues reside in helix-8 (K195, 206, 208), and three in helix-10 (K226, 238, 239). To determine the role of each CT lysine residue in apoA-I self-association, single, double and triple lysine to glutamine mutants were engineered via site-directed mutagenesis. Circular dichroism and chemical denaturation analysis revealed all mutants retained their structural integrity. Chemical crosslinking and size-exclusion chromatography showed a small effect on self-association when helix-8 lysine residues were changed into glutamine. In contrast, mutation of the three helix-10 lysine residues resulted in a predominantly monomeric protein and K226 was identified as a critical residue. When helix-10 glutamate residues 223, 234, or 235 were substituted with glutamine, reduced self-association was observed similar to that of the helix-10 lysine variants, suggesting ionic interactions between these residues. Thus, helix-10 is a critical part of apoA-I mediating self-association, and disruption of ionic interactions changes apoA-I from an oligomeric state into a monomer. Since the helix-10 triple mutant solubilized phospholipid vesicles at higher rates compared to wild-type apoA-I, this indicates monomeric apoA-I is more potent in lipid binding, presumably because helix-10 is fully accessible to interact with lipids.
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Affiliation(s)
- John P Burdick
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Rohin S Basi
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Kaitlyn S Burns
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Paul M M Weers
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA.
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5
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Wang YP, Yang LN, Feng YY, Liu S, Zhan J. Single Amino Acid Substitution the DNA Repairing Gene Radiation-Sensitive 4 Contributes to Ultraviolet Tolerance of a Plant Pathogen. Front Microbiol 2022; 13:927139. [PMID: 35910660 PMCID: PMC9330021 DOI: 10.3389/fmicb.2022.927139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
To successfully survive and reproduce, all species constantly modify the structure and expression of their genomes to cope with changing environmental conditions including ultraviolet (UV) radiation. Thus, knowledge of species adaptation to environmental changes is a central theme of evolutionary studies which could have important implication for disease management and social-ecological sustainability in the future but is generally insufficient. Here, we investigated the evolution of UV adaptation in organisms by population genetic analysis of sequence structure, physiochemistry, transcription, and fitness variation in the radiation-sensitive 4 (RAD4) gene of the Irish potato famine pathogen Phytophthora infestans sampled from various altitudes. We found that RAD4 is a key gene determining the resistance of the pathogen to UV stress as indicated by strong phenotype-genotype-geography associations and upregulated transcription after UV exposure. We also found conserved evolution in the RAD4 gene. Only five nucleotide haplotypes corresponding to three protein isoforms generated by point mutations were detected in the 140 sequences analyzed and the mutations were constrained to the N-terminal domain of the protein. Physiochemical changes associated with non-synonymous mutations generate severe fitness penalty to mutants, which are purged out by natural selection, leading to the conserved evolution observed in the gene.
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Affiliation(s)
- Yan-Ping Wang
- Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, College of Chemistry and Life Sciences, Chengdu Normal University, Chengdu, China
| | - Li-Na Yang
- Institute of Oceanography, Minjiang University, Fuzhou, China
| | - Yuan-Yuan Feng
- Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, College of Chemistry and Life Sciences, Chengdu Normal University, Chengdu, China
| | - Songqing Liu
- Sichuan Provincial Key Laboratory for Development and Utilization of Characteristic Horticultural Biological Resources, College of Chemistry and Life Sciences, Chengdu Normal University, Chengdu, China
- *Correspondence: Songqing Liu,
| | - Jiasui Zhan
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Jiasui Zhan,
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Secretory granule exocytosis and its amplification by cAMP in pancreatic β-cells. Diabetol Int 2022; 13:471-479. [PMID: 35694000 PMCID: PMC9174382 DOI: 10.1007/s13340-022-00580-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
Abstract
The sequence of events for secreting insulin in response to glucose in pancreatic β-cells is termed "stimulus-secretion coupling". The core of stimulus-secretion coupling is a process which generates electrical activity in response to glucose uptake and causes Ca2+ oscillation for triggering exocytosis of insulin-containing secretory granules. Prior to exocytosis, the secretory granules are mobilized and docked to the plasma membrane and primed for fusion with the plasma membrane. Together with the final fusion with the plasma membrane, these steps are named the exocytosis process of insulin secretion. The steps involved in the exocytosis process are crucial for insulin release from β-cells and considered indispensable for glucose homeostasis. We recently confirmed a signature of defective exocytosis process in human islets and β-cells of obese donors with type 2 diabetes (T2D). Furthermore, cyclic AMP (cAMP) potentiates glucose-stimulated insulin secretion through mechanisms including accelerating the exocytosis process. In this mini-review, we aimed to organize essential knowledge of the secretory granule exocytosis and its amplification by cAMP. Then, we suggest the fatty acid translocase CD36 as a predisposition in β-cells for causing defective exocytosis, which is considered a pathogenesis of T2D in relation to obesity. Finally, we propose potential therapeutics of the defective exocytosis based on a CD36-neutralizing antibody and on Apolipoprotein A-I (ApoA-I), for improving β-cell function in T2D.
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7
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Effect of hydrophobic moment on membrane interaction and cell penetration of apolipoprotein E-derived arginine-rich amphipathic α-helical peptides. Sci Rep 2022; 12:4959. [PMID: 35322082 PMCID: PMC8943082 DOI: 10.1038/s41598-022-08876-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/14/2022] [Indexed: 12/15/2022] Open
Abstract
We previously developed an amphipathic arginine-rich peptide, A2-17, which has high ability to directly penetrate across cell membranes. To understand the mechanism of the efficient cell-penetrating ability of the A2-17 peptide, we designed three structural isomers of A2-17 having different values of the hydrophobic moment and compared their membrane interaction and direct cell penetration. Confocal fluorescence microscopy revealed that cell penetration efficiency of peptides tends to increase with their hydrophobic moment, in which A2-17 L14R/R15L, an A2-17 isomer with the highest hydrophobic moment, predominantly remains on plasma cell membranes. Consistently, Trp fluorescence analysis indicated the deepest insertion of A2-17 L14R/R15L into lipid membranes among all A2-17 isomers. Electrophysiological analysis showed that the duration and charge flux of peptide-induced pores in lipid membranes were prominent for A2-17 L14R/R15L, indicating the formation of stable membrane pores. Indeed, the A2-17 L14R/R15L peptide exhibited the strongest membrane damage to CHO-K1 cells. Atomic force microscopy quantitatively defined the peptide-induced membrane perturbation as the decrease in the stiffness of lipid vesicles, which was correlated with the hydrophobic moment of all A2-17 isomers. These results indicate that optimal membrane perturbation by amphipathic A2-17 peptide is critical for its efficient penetration into cells without inducing stabilized membrane pores.
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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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9
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Interaction of lipid-free apolipoprotein A-I with cholesterol revealed by molecular modeling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140614. [PMID: 33548491 DOI: 10.1016/j.bbapap.2021.140614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/23/2021] [Accepted: 01/28/2021] [Indexed: 11/22/2022]
Abstract
We report the modeling of the interaction of differently self-associated lipid-free apoA-I with cholesterol monomer and tail-to-tail (TT) or face-to-face (FF) cholesterol dimer. Cholesterol dimerization is exploited to reconcile the existing experimental data on cholesterol binding to apoA-I with extremely low critical micelle concentration of cholesterol. Two crystal structures of 1-43 N-truncated apolipoprotein Δ(1-43)A-I tetramer (PDB ID: 1AV1, structure B), 185-243 C-truncated apolipoprotein Δ(185-243)A-I dimer (PDB ID: 3R2P, structure M) were analyzed. Cholesterol monomers bind to multiple binding sites in apoA-I monomer, dimer and tetramer with low, moderate and high energy (-10 to -28 kJ/mol with Schrödinger package), still insufficient to overcome the thermodynamic restriction by cholesterol micellization (-52.8 kJ/mol). The binding sites partially coincide with the putative cholesterol-binding motifs. However, apoA-I monomer and dimer existing in structure B, that contain nonoverlapping and non-interacting pairs of binding sites with high affinity for TT and FF cholesterol dimers, can bind in common 14 cholesterol molecules that correspond to existing values. ApoA-I monomer and dimer in structure M can bind in common 6 cholesterol molecules. The values of respective total energy of cholesterol binding up to 64.5 and 67.0 kJ/mol for both B and M structures exceed the free energy of cholesterol micellization. We hypothesize that cholesterol dimers may simultaneously interact with extracellular monomer and dimer of lipid-free apoA-I, that accumulate at acid pH in atheroma. The thermodynamically allowed apolipoprotein-cholesterol interaction outside the macrophage may represent a new mechanism of cholesterol transport by apoA-I from atheroma, in addition to ABCA1-mediated cholesterol efflux.
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10
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Zhang X, Wang K, Zhu L, Wang Q. Reverse Cholesterol Transport Pathway and Cholesterol Efflux in Diabetic Retinopathy. J Diabetes Res 2021; 2021:8746114. [PMID: 34746320 PMCID: PMC8564209 DOI: 10.1155/2021/8746114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/16/2021] [Accepted: 10/01/2021] [Indexed: 11/21/2022] Open
Abstract
Cholesterol esters, synthesized from cholesterol with long-chain fatty acids, are essential components of plasma lipoproteins and cell membranes that participate in various metabolic processes in the body. Cholesterol can be excreted through the cholesterol reverse transport (RCT) pathway when excessive cholesterol is produced in the extrahepatic cells, which is regulated by the liver X receptor (LXR) and its downstream regulators ATP-binding cassette subfamily A member 1 (ABCA1) and ATP-binding cassette subfamily G member 1 (ABCG1) genes. Abnormal cholesterol metabolism is closely associated with the development of diabetic retinopathy (DR). However, the precise underlying mechanism of the RCT pathway in the pathogenesis of DR is still not fully understood. This review focused on cholesterol metabolism, with a particular emphasis on the RCT pathway and its correlation with the development of DR. Particular attention has been paid to the key regulators of the RCT pathway: LXR, ABCA1, and ABCG1 genes and their potential therapeutic targets in the management of DR.
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Affiliation(s)
- Xinyuan Zhang
- Beijing Institute of Ophthalmology, Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, China
- Beijing Retinal and Choroidal Vascular Study Group, China
| | - Kaiyue Wang
- Beijing Institute of Ophthalmology, Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, China
| | - Ling Zhu
- Save Sight Institute, University of Sydney, Australia
| | - Qiyun Wang
- Beijing Institute of Ophthalmology, Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, China
- Beijing Retinal and Choroidal Vascular Study Group, China
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Ohgita T, Takechi-Haraya Y, Okada K, Matsui S, Takeuchi M, Saito C, Nishitsuji K, Uchimura K, Kawano R, Hasegawa K, Sakai-Kato K, Akaji K, Izutsu KI, Saito H. Enhancement of direct membrane penetration of arginine-rich peptides by polyproline II helix structure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183403. [DOI: 10.1016/j.bbamem.2020.183403] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/29/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023]
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12
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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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13
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First eight residues of apolipoprotein A-I mediate the C-terminus control of helical bundle unfolding and its lipidation. PLoS One 2020; 15:e0221915. [PMID: 31945064 PMCID: PMC6964839 DOI: 10.1371/journal.pone.0221915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/30/2019] [Indexed: 11/23/2022] Open
Abstract
The crystal structure of a C-terminal deletion of apolipoprotein A-I (apoA1) shows a large helical bundle structure in the amino half of the protein, from residues 8 to 115. Using site directed mutagenesis, guanidine or thermal denaturation, cell free liposome clearance, and cellular ABCA1-mediated cholesterol efflux assays, we demonstrate that apoA1 lipidation can occur when the thermodynamic barrier to this bundle unfolding is lowered. The absence of the C-terminus renders the bundle harder to unfold resulting in loss of apoA1 lipidation that can be reversed by point mutations, such as Trp8Ala, and by truncations as short as 8 residues in the amino terminus, both of which facilitate helical bundle unfolding. Locking the bundle via a disulfide bond leads to loss of apoA1 lipidation. We propose a model in which the C-terminus acts on the N-terminus to destabilize this helical bundle. Upon lipid binding to the C-terminus, Trp8 is displaced from its interaction with Phe57, Arg61, Leu64, Val67, Phe71, and Trp72 to destabilize the bundle. However, when the C-terminus is deleted, Trp8 cannot be displaced, the bundle cannot unfold, and apoA1 cannot be lipidated.
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14
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Gkolfinopoulou C, Bourtsala A, Chroni A. Structural and functional basis for increased HDL-cholesterol levels due to the naturally occurring V19L mutation in human apolipoprotein A-I. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158593. [PMID: 31863971 DOI: 10.1016/j.bbalip.2019.158593] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/09/2019] [Accepted: 12/16/2019] [Indexed: 11/26/2022]
Abstract
Several hereditary point mutations in human apolipoprotein A-I (apoA-I) have been associated with low HDL-cholesterol levels and/or increased coronary artery disease (CAD) risk. However, one apoA-I mutation, the V19L, recently identified in Icelanders, has been associated with increased HDL-cholesterol levels and decreased CAD risk. In an effort to gain mechanistic insight linking the presence of this mutation in apoA-I with the increase of HDL-cholesterol levels we evaluated the effect of V19L mutation on the conformational integrity and functional properties of apoA-I in lipid-free and lipidated form. ApoA-I[V19L] was found to be thermodynamically destabilized in lipid-free form and displays an increased capacity to associate with phospholipids compared to WT apoA-I. When associated to reconstituted HDL (rHDL), apoA-I[V19L] was more thermodynamically stabilized than WT apoA-I. ApoA-I[V19L] displayed normal capacity to promote ABCA1-mediated cholesterol efflux and to activate the enzyme LCAT, in lipid-free and rHDL-associated forms, respectively. Additionally, rHDL-associated apoA-I[V19L] showed normal capacity to promote ABCG1-mediated cholesterol efflux, but 45% increased capacity to promote SR-BI-mediated cholesterol efflux, while the SR-BI-mediated HDL-lipid uptake was normal. Overall, our findings show that the apoA-I V19L mutation does not affect the first steps of HDL biogenesis pathway. However, the increased capacity of apoA-I[V19L] to associate with phospholipids, in combination with the enhanced thermodynamic stability of lipoprotein-associated apoA-I[V19L] and increased capacity of apoA-I[V19L]-containing lipoprotein particles to accept additional cholesterol by SR-BI could account for the increased HDL-cholesterol levels observed in human carriers of the mutation.
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Affiliation(s)
- Christina Gkolfinopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos", Agia Paraskevi, Athens, Greece
| | - Angeliki Bourtsala
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos", Agia Paraskevi, Athens, Greece
| | - Angeliki Chroni
- Institute of Biosciences and Applications, National Center for Scientific Research "Demokritos", Agia Paraskevi, Athens, Greece.
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15
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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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16
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Ohgita T, Takechi-Haraya Y, Nadai R, Kotani M, Tamura Y, Nishikiori K, Nishitsuji K, Uchimura K, Hasegawa K, Sakai-Kato K, Akaji K, Saito H. A novel amphipathic cell-penetrating peptide based on the N-terminal glycosaminoglycan binding region of human apolipoprotein E. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:541-549. [DOI: 10.1016/j.bbamem.2018.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 11/17/2018] [Accepted: 12/13/2018] [Indexed: 11/15/2022]
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17
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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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18
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Melchior JT, Walker RG, Cooke AL, Morris J, Castleberry M, Thompson TB, Jones MK, Song HD, Rye KA, Oda MN, Sorci-Thomas MG, Thomas MJ, Heinecke JW, Mei X, Atkinson D, Segrest JP, Lund-Katz S, Phillips MC, Davidson WS. A consensus model of human apolipoprotein A-I in its monomeric and lipid-free state. Nat Struct Mol Biol 2017; 24:1093-1099. [PMID: 29131142 PMCID: PMC5749415 DOI: 10.1038/nsmb.3501] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/06/2017] [Indexed: 11/09/2022]
Abstract
Apolipoprotein (apo)A-I is an organizing scaffold protein that is critical to high-density lipoprotein (HDL) structure and metabolism, probably mediating many of its cardioprotective properties. However, HDL biogenesis is poorly understood, as lipid-free apoA-I has been notoriously resistant to high-resolution structural study. Published models from low-resolution techniques share certain features but vary considerably in shape and secondary structure. To tackle this central issue in lipoprotein biology, we assembled a team of structural biologists specializing in apolipoproteins and set out to build a consensus model of monomeric lipid-free human apoA-I. Combining novel and published cross-link constraints, small-angle X-ray scattering (SAXS), hydrogen-deuterium exchange (HDX) and crystallography data, we propose a time-averaged model consistent with much of the experimental data published over the last 40 years. The model provides a long-sought platform for understanding and testing details of HDL biogenesis, structure and function.
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Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Ryan G Walker
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Allison L Cooke
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Jamie Morris
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Mark Castleberry
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Thomas B Thompson
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Martin K Jones
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hyun D Song
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Kerry-Anne Rye
- School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Michael N Oda
- Children's Hospital Oakland Research Institute, Oakland, California, USA
| | - Mary G Sorci-Thomas
- Department of Medicine, Section on Endocrinology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Michael J Thomas
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Jay W Heinecke
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Xiaohu Mei
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - David Atkinson
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jere P Segrest
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Sissel Lund-Katz
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael C Phillips
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
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19
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Synchrotron radiation circular dichroism spectroscopy reveals structural divergences in HDL-bound apoA-I variants. Sci Rep 2017; 7:13540. [PMID: 29051568 PMCID: PMC5648894 DOI: 10.1038/s41598-017-13878-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/03/2017] [Indexed: 12/15/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) in high-density lipoprotein (HDL) provides cardiovascular protection. Synchrotron radiation circular dichroism (SRCD) spectroscopy was used to analyze the dynamic solution structure of the apoA-I protein in the apo- and HDL-states and the protein structure conversion in HDL formation. Wild-type apoA-I protein was compared to human variants that either are protective (R173C, Milano) or lead to increased risk for ischaemic heart disease (A164S). Comparable secondary structure distributions in the HDL particles, including significant levels of beta strand/turn, were observed. ApoA-I Milano in HDL displayed larger size heterogeneity, increased protein flexibility, and an altered lipid-binding profile, whereas the apoA-I A164S in HDL showed decrease thermal stability, potentially linking the intrinsic HDL propensities of the variants to disease risk.
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20
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Kimura H, Mikawa S, Mizuguchi C, Horie Y, Morita I, Oyama H, Ohgita T, Nishitsuji K, Takeuchi A, Lund-Katz S, Akaji K, Kobayashi N, Saito H. Immunochemical Approach for Monitoring of Structural Transition of ApoA-I upon HDL Formation Using Novel Monoclonal Antibodies. Sci Rep 2017; 7:2988. [PMID: 28592796 PMCID: PMC5462821 DOI: 10.1038/s41598-017-03208-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/24/2017] [Indexed: 11/24/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) undergoes a large conformational reorganization during remodeling of high-density lipoprotein (HDL) particles. To detect structural transition of apoA-I upon HDL formation, we developed novel monoclonal antibodies (mAbs). Splenocytes from BALB/c mice immunized with a recombinant human apoA-I, with or without conjugation with keyhole limpet hemocyanin, were fused with P3/NS1/1-Ag4-1 myeloma cells. After the HAT-selection and cloning, we established nine hybridoma clones secreting anti-apoA-I mAbs in which four mAbs recognize epitopes on the N-terminal half of apoA-I while the other five mAbs recognize the central region. ELISA and bio-layer interferometry measurements demonstrated that mAbs whose epitopes are within residues 1–43 or 44–65 obviously discriminate discoidal and spherical reconstituted HDL particles despite their great reactivities to lipid-free apoA-I and plasma HDL, suggesting the possibility of these mAbs to detect structural transition of apoA-I on HDL. Importantly, a helix-disrupting mutation of W50R into residues 44–65 restored the immunoreactivity of mAbs whose epitope being within residues 44–65 against reconstituted HDL particles, indicating that these mAbs specifically recognize the epitope region in a random coil state. These results encourage us to develop mAbs targeting epitopes in the N-terminal residues of apoA-I as useful probes for monitoring formation and remodeling of HDL particles.
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Affiliation(s)
- Hitoshi Kimura
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan.,Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Shiho Mikawa
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan.,Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Chiharu Mizuguchi
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan.,Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Yuki Horie
- Department of Bioanalytical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kitamachi, Higashinada-ku, Kobe, 658-8558, Japan
| | - Izumi Morita
- Department of Bioanalytical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kitamachi, Higashinada-ku, Kobe, 658-8558, Japan
| | - Hiroyuki Oyama
- Department of Bioanalytical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kitamachi, Higashinada-ku, Kobe, 658-8558, Japan
| | - Takashi Ohgita
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Kazuchika Nishitsuji
- Department of Molecular Pathology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Atsuko Takeuchi
- Analytical Laboratory, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kitamachi, Higashinada-ku, Kobe, 658-8558, Japan
| | - Sissel Lund-Katz
- Lipid Research Group, Gastroenterology, Hepatology and Nutrition Division, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, 19104-4318, USA
| | - Kenichi Akaji
- Department of Medicinal Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Norihiro Kobayashi
- Department of Bioanalytical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kitamachi, Higashinada-ku, Kobe, 658-8558, Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto, 607-8414, Japan.
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21
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Tanaka M, Nishimura A, Takeshita H, Takase H, Yamada T, Mukai T. Effect of lipid environment on amyloid fibril formation of human serum amyloid A. Chem Phys Lipids 2017; 202:6-12. [DOI: 10.1016/j.chemphyslip.2016.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/14/2016] [Accepted: 11/14/2016] [Indexed: 10/20/2022]
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22
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Thermal protein unfolding by differential scanning calorimetry and circular dichroism spectroscopy Two-state model versus sequential unfolding. Q Rev Biophys 2016; 49:e9. [PMID: 27658613 DOI: 10.1017/s0033583516000044] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Thermally-induced protein unfolding is commonly described with the two-state model. This model assumes only two types of protein molecules in solution, the native (N) and the denatured, unfolded (U) protein. In reality, protein unfolding is a multistep process, even if intermediate states are only sparsely populated. As an alternative approach we explore the Zimm-Bragg theory, originally developed for the α-helix-to-random coil transition of synthetic polypeptides. The theory includes intermediate structures with concentrations determined by the cooperativity of the unfolding reaction. We illustrate the differences between the two-state model and the Zimm-Bragg theory with measurements of apolipoprotein A-1 and lysozyme by differential scanning calorimetry (DSC) and CD spectroscopy. Nine further protein examples are taken from the literature. The Zimm-Bragg theory provides a perfect fit of the calorimetric unfolding transitions for all proteins investigated. In contrast, the transition curves and enthalpies predicted by the two-state model differ considerably from the experimental results. Apolipoprotein A-1 is ~50% α-helical at ambient temperature and its unfolding follows the classical α-helix-to-random coil equilibrium. The unfolding of proteins with little α-helix content, such as lysozyme, can also be analyzed with the Zimm-Bragg theory by introducing the concept of 'folded' and 'unfolded' peptide units assuming an average unfolding enthalpy per peptide unit. DSC is the method of choice to measure the unfolding enthalpy, , but CD spectroscopy in combination with the two-state model is often used to deduce the unfolding enthalpy. This can lead to erroneous result. Not only are different enthalpies required to describe the CD and DSC transition curves but these values deviate distinctly from the experimental result. In contrast, the Zimm-Bragg theory predicts the DSC and CD unfolding transitions with the same set of parameters.
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23
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Petrlova J, Hilt S, Budamagunta M, Domingo-Espín J, Voss JC, Lagerstedt JO. Molecular crowding impacts the structure of apolipoprotein A-I with potential implications on in vivo metabolism and function. Biopolymers 2016; 105:683-92. [PMID: 27122373 DOI: 10.1002/bip.22865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/14/2016] [Accepted: 04/25/2016] [Indexed: 11/08/2022]
Abstract
The effect molecular crowding, defined as the volume exclusion exerted by one soluble inert molecule upon another soluble molecule, has on the structure and self-interaction of lipid-free apoA-I were explored. The influence of molecular crowding on lipid-free apoA-I oligomerization and internal dynamics has been analyzed using electron paramagnetic resonance (EPR) spectroscopy measurements of nitroxide spin label at selected positions throughout the protein sequence and at varying concentrations of the crowding agent Ficoll-70. The targeted positions include sites previously shown to be sensitive for detecting intermolecular interaction via spin-spin coupling. Circular dichroism was used to study secondary structural changes in lipid-free apoA-I imposed by increasing concentrations of the crowding agent. Crosslinking and SDS-PAGE gel analysis was employed to further characterize the role molecular crowding plays in inducing apoA-I oligomerization. It was concluded that the dynamic apoA-I structure and oligomeric state was altered in the presence of the crowding agent. It was also found that the C-terminal was slightly more sensitive to molecular crowding. Finally, the data described the region around residue 217 in the C-terminal domain of apoA-I as the most sensitive reporter of the crowding-induced self-association of apoA-I. The implications of this behavior to in vivo functionality are discussed. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 683-692, 2016.
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Affiliation(s)
- Jitka Petrlova
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
| | - Silvia Hilt
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Madhu Budamagunta
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Joan Domingo-Espín
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
| | - John C Voss
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.,Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Jens O Lagerstedt
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
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24
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Update on the molecular biology of dyslipidemias. Clin Chim Acta 2016; 454:143-85. [DOI: 10.1016/j.cca.2015.10.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/24/2015] [Accepted: 10/30/2015] [Indexed: 12/20/2022]
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25
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Kariyazono H, Nadai R, Miyajima R, Takechi-Haraya Y, Baba T, Shigenaga A, Okuhira K, Otaka A, Saito H. Formation of stable nanodiscs by bihelical apolipoprotein A-I mimetic peptide. J Pept Sci 2016; 22:116-22. [PMID: 26780967 DOI: 10.1002/psc.2847] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/14/2015] [Accepted: 12/02/2015] [Indexed: 01/09/2023]
Abstract
Nanodiscs are composed of scaffold protein or peptide such as apolipoprotein A-I (apoA-I) and phospholipids. Although peptide-based nanodiscs have an advantage to modulate the size of nanodiscs by changing phospholipid/peptide ratios, they are usually less stable than apoA-I-based nanodiscs. In this study, we designed a novel nanodisc scaffold peptide (NSP) that has proline-punctuated bihelical amphipathic structure based on apoA-I mimetic peptides. NSP formed α-helical structure on 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) nanodiscs prepared by cholate dialysis method. Dynamic light scattering measurements demonstrated that diameters of NSP nanodiscs vary depending upon POPC/NSP ratios. Comparison of thermal unfolding of nanodiscs monitored by circular dichroism measurements demonstrated that NSP forms much more stable nanodiscs with POPC than monohelical peptide, 4F, exhibiting comparable stability to apoA-I-POPC nanodiscs. Intrinsic Trp fluorescence measurements showed that Trp residues of NSP exhibit more hydrophobic environment than that of 4 F on nanodiscs, suggesting the stronger interaction of NSP with phospholipids. Thus, the bihelical structure of NSP appears to increase the stability of nanodiscs because of the enhanced interaction of peptides with phospholipids. In addition, NSP as well as 4F spontaneously solubilized POPC vesicles into nanodiscs without using detergent. These results indicate that bihelical NSP forms nanodiscs with comparable stability to apoA-I and has an ability to control the size of nanodiscs simply by changing phospholipid/peptide ratios.
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Affiliation(s)
- Hirokazu Kariyazono
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Ryo Nadai
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Rin Miyajima
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan
| | - Yuki Takechi-Haraya
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, Japan.,Division of Drugs, National Institute of Health Sciences, Tokyo, 158-8501, Japan
| | - Teruhiko Baba
- Research Center for Stem Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8565, Japan
| | - Akira Shigenaga
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima, 770-8505, 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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26
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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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ZHOU LINGYAN, LI CONGCONG, GAO LING, WANG AIHONG. High-density lipoprotein synthesis and metabolism (Review). Mol Med Rep 2015; 12:4015-4021. [DOI: 10.3892/mmr.2015.3930] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 03/26/2015] [Indexed: 11/06/2022] Open
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Smaller Nanodiscs are Suitable for Studying Protein Lipid Interactions by Solution NMR. Protein J 2015; 34:205-11. [DOI: 10.1007/s10930-015-9613-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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29
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30
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Mizuguchi C, Hata M, Dhanasekaran P, Nickel M, Okuhira K, Phillips MC, Lund-Katz S, Saito H. Fluorescence study of domain structure and lipid interaction of human apolipoproteins E3 and E4. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1841:1716-24. [PMID: 25281910 DOI: 10.1016/j.bbalip.2014.09.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/06/2014] [Accepted: 09/24/2014] [Indexed: 12/19/2022]
Abstract
Human apolipoprotein E (apoE) isoforms exhibit different conformational stabilities and lipid-binding properties that give rise to altered cholesterol metabolism among the isoforms. Using Trp-substituted mutations and site- directed fluorescence labeling, we made a comprehensive comparison of the conformational organization of the N- and C-terminal domains and lipid interactions between the apoE3 and apoE4 isoforms. Trp fluorescence measurements for selectively Trp-substituted variants of apoE isoforms demonstrated that apoE4 adopts less stable conformations in both the N- and C-terminal domains compared to apoE3. Consistent with this, the conformational reorganization of the N-terminal helix bundle occurs at lower guanidine hydrochloride concentration in apoE4 than in apoE3 as monitored by fluorescence resonance energy transfer (FRET) from Trp residues to acrylodan attached at the N-terminal helix. Upon binding of apoE3 and apoE4 variants to egg phosphatidylcholine small unilamellar vesicles, similar changes in Trp fluorescence or FRET efficiency were observed for the isoforms, indi- cating that the opening of the N-terminal helix bundle occurs similarly in apoE3 and apoE4. Introduction of mutations into the C-terminal domain of the apoE isoforms to prevent self-association and maintain the monomeric state resulted in great increase in the rate of binding of the C-terminal helices to a lipid surface. Overall, our results demonstrate that the different conformational organizations of the N- and C-terminal domains have a minor effect on the steady-state lipid-binding behavior of apoE3 and apoE4: rather, self-association property is a critical determinant in the kinetics of lipid binding through the C-terminal helices of apoE isoforms.
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31
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Zhang X, Lei D, Zhang L, Rames M, Zhang S. A model of lipid-free apolipoprotein A-I revealed by iterative molecular dynamics simulation. PLoS One 2015; 10:e0120233. [PMID: 25793886 PMCID: PMC4368682 DOI: 10.1371/journal.pone.0120233] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 01/29/2015] [Indexed: 01/06/2023] Open
Abstract
Apolipoprotein A-I (apo A-I), the major protein component of high-density lipoprotein, has been proven inversely correlated to cardiovascular risk in past decades. The lipid-free state of apo A-I is the initial stage which binds to lipids forming high-density lipoprotein. Molecular models of lipid-free apo A-I have been reported by methods like X-ray crystallography and chemical cross-linking/mass spectrometry (CCL/MS). Through structural analysis we found that those current models had limited consistency with other experimental results, such as those from hydrogen exchange with mass spectrometry. Through molecular dynamics simulations, we also found those models could not reach a stable equilibrium state. Therefore, by integrating various experimental results, we proposed a new structural model for lipid-free apo A-I, which contains a bundled four-helix N-terminal domain (1–192) that forms a variable hydrophobic groove and a mobile short hairpin C-terminal domain (193–243). This model exhibits an equilibrium state through molecular dynamics simulation and is consistent with most of the experimental results known from CCL/MS on lysine pairs, fluorescence resonance energy transfer and hydrogen exchange. This solution-state lipid-free apo A-I model may elucidate the possible conformational transitions of apo A-I binding with lipids in high-density lipoprotein formation.
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Affiliation(s)
- Xing Zhang
- Department of Applied Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Dongsheng Lei
- Department of Applied Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Lei Zhang
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Matthew Rames
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Shengli Zhang
- Department of Applied Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China
- * E-mail:
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32
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Handa D, Kimura H, Oka T, Takechi Y, Okuhira K, Phillips MC, Saito H. Kinetic and thermodynamic analyses of spontaneous exchange between high-density lipoprotein-bound and lipid-free apolipoprotein A-I. Biochemistry 2015; 54:1123-31. [PMID: 25564321 DOI: 10.1021/bi501345j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
It is thought that apolipoprotein A-I (apoA-I) spontaneously exchanges between high-density lipoprotein (HDL)-bound and lipid-free states, which is relevant to the occurrence of preβ-HDL particles in plasma. To improve our understanding of the mechanistic basis for this phenomenon, we performed kinetic and thermodynamic analyses for apoA-I exchange between discoidal HDL-bound and lipid-free forms using fluorescence-labeled apoA-I variants. Gel filtration experiments demonstrated that addition of excess lipid-free apoA-I to discoidal HDL particles promotes exchange of apoA-I between HDL-associated and lipid-free pools without alteration of the steady-state HDL particle size. Kinetic analysis of time-dependent changes in NBD fluorescence upon the transition of NBD-labeled apoA-I from HDL-bound to lipid-free state indicates that the exchange kinetics are independent of the collision frequency between HDL-bound and lipid-free apoA-I, in which the lipid binding ability of apoA-I affects the rate of association of lipid-free apoA-I with the HDL particles and not the rate of dissociation of HDL-bound apoA-I. Thus, C-terminal truncations or mutations that reduce the lipid binding affinity of apoA-I strongly impair the transition of lipid-free apoA-I to the HDL-bound state. Thermodynamic analysis of the exchange kinetics demonstrated that the apoA-I exchange process is enthalpically unfavorable but entropically favorable. These results explain the thermodynamic basis of the spontaneous exchange reaction of apoA-I associated with HDL particles. The altered exchangeability of dysfunctional apoA-I would affect HDL particle rearrangement, leading to perturbed HDL metabolism.
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Affiliation(s)
- Daisuke Handa
- Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, Tokushima University , 1-78-1 Shomachi, Tokushima 770-8505, Japan
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33
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Castelletto V, Hamley IW, Reza M, Ruokolainen J. Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif. NANOSCALE 2015; 7:171-178. [PMID: 25406726 DOI: 10.1039/c4nr05072j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interaction of a designed bioactive lipopeptide C16-GGGRGDS, comprising a hexadecyl lipid chain attached to a functional heptapeptide, with the lipid-free apoliprotein, Apo-AI, is examined. This apolipoprotein is a major component of high density lipoprotein and it is involved in lipid metabolism and may serve as a biomarker for cardiovascular disease and Alzheimers' disease. We find via isothermal titration calorimetry that binding between the lipopeptide and Apo-AI occurs up to a saturation condition, just above equimolar for a 10.7 μM concentration of Apo-AI. A similar value is obtained from circular dichroism spectroscopy, which probes the reduction in α-helical secondary structure of Apo-AI upon addition of C16-GGGRGDS. Electron microscopy images show a persistence of fibrillar structures due to self-assembly of C16-GGGRGDS in mixtures with Apo-AI above the saturation binding condition. A small fraction of spheroidal or possibly "nanodisc" structures was observed. Small-angle X-ray scattering (SAXS) data for Apo-AI can be fitted using a published crystal structure of the Apo-AI dimer. The SAXS data for the lipopeptide/Apo-AI mixtures above the saturation binding conditions can be fitted to the contribution from fibrillar structures coexisting with flat discs corresponding to Apo-AI/lipopeptide aggregates.
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Affiliation(s)
- V Castelletto
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
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34
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Zeno WF, Hilt S, Aravagiri K, Risbud SH, Voss JC, Parikh AN, Longo ML. Analysis of lipid phase behavior and protein conformational changes in nanolipoprotein particles upon entrapment in sol-gel-derived silica. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9780-9788. [PMID: 25062385 PMCID: PMC4140539 DOI: 10.1021/la5025058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 07/24/2014] [Indexed: 06/02/2023]
Abstract
The entrapment of nanolipoprotein particles (NLPs) and liposomes in transparent, nanoporous silica gel derived from the precursor tetramethylorthosilicate was investigated. NLPs are discoidal patches of lipid bilayer that are belted by amphiphilic scaffold proteins and have an average thickness of 5 nm. The NLPs in this work had a diameter of roughly 15 nm and utilized membrane scaffold protein (MSP), a genetically altered variant of apolipoprotein A-I. Liposomes have previously been examined inside of silica sol-gels and have been shown to exhibit instability. This is attributed to their size (∼150 nm) and altered structure and constrained lipid dynamics upon entrapment within the nanometer-scale pores (5-50 nm) of the silica gel. By contrast, the dimensional match of NLPs with the intrinsic pore sizes of silica gel opens the possibility for their entrapment without disruption. Here we demonstrate that NLPs are more compatible with the nanometer-scale size of the porous environment by analysis of lipid phase behavior via fluorescence anisotropy and analysis of scaffold protein secondary structure via circular dichroism spectroscopy. Our results showed that the lipid phase behavior of NLPs entrapped inside of silica gel display closer resemblance to its solution behavior, more so than liposomes, and that the MSP in the NLPs maintain the high degree of α-helix secondary structure associated with functional protein-lipid interactions after entrapment. We also examined the effects of residual methanol on lipid phase behavior and the size of NLPs and found that it exerts different influences in solution and in silica gel; unlike in free solution, silica entrapment may be inhibiting NLP size increase and/or aggregation. These findings set precedence for a bioinorganic hybrid nanomaterial that could incorporate functional integral membrane proteins.
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Affiliation(s)
- Wade F. Zeno
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - Silvia Hilt
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - Kannan
K. Aravagiri
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - Subhash H. Risbud
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - John C. Voss
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - Atul N. Parikh
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
| | - Marjorie L. Longo
- Department
of Chemical Engineering and Materials Science and Department of
Biochemistry and Molecular Medicine, University
of California Davis, Davis, California 95616, United States
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35
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Takase H, Furuchi H, Tanaka M, Yamada T, Matoba K, Iwasaki K, Kawakami T, Mukai T. Characterization of reconstituted high-density lipoprotein particles formed by lipid interactions with human serum amyloid A. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1842:1467-74. [PMID: 25063355 DOI: 10.1016/j.bbalip.2014.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 12/21/2022]
Abstract
The acute-phase human protein serum amyloid A (SAA) is enriched in high-density lipoprotein (HDL) in patients with inflammatory diseases. Compared with normal HDL containing apolipoprotein A-I, which is the principal protein component, characteristics of acute-phase HDL containing SAA remain largely undefined. In the present study, we examined the physicochemical properties of reconstituted HDL (rHDL) particles formed by lipid interactions with SAA. Fluorescence and circular dichroism measurements revealed that although SAA was unstructured at physiological temperature, α-helix formation was induced upon binding to phospholipid vesicles. SAA also formed rHDL particles by solubilizing phospholipid vesicles through mechanisms that are common to other exchangeable apolipoproteins. Dynamic light scattering and nondenaturing gradient gel electrophoresis analyses of rHDL after gel filtration revealed particle sizes of approximately 10nm, and a discoidal shape was verified by transmission electron microscopy. Thermal denaturation experiments indicated that SAA molecules in rHDL retained α-helical conformations at 37°C, but were almost completely denatured around 60°C. Furthermore, trypsin digestion experiments showed that lipid binding rendered SAA molecules resistant to protein degradation. In humans, three major SAA1 isoforms (SAA1.1, 1.3, and 1.5) are known. Although these isoforms have different amino acids at residues 52 and 57, no major differences in physicochemical properties between rHDL particles resulting from lipid interactions with SAA isoforms have been found. The present data provide useful insights into the effects of SAA enrichment on the physicochemical properties of HDL.
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Affiliation(s)
- Hiroka Takase
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan
| | - Hiroki Furuchi
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan
| | - Masafumi Tanaka
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan.
| | - Toshiyuki Yamada
- Department of Clinical and Laboratory Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Kyoko Matoba
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita 565-0871, Japan
| | - Kenji Iwasaki
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Suita 565-0871, Japan
| | - Toru Kawakami
- Laboratory of Protein Organic Chemistry, Institute for Protein Research, Osaka University, Suita 565-0871, Japan
| | - Takahiro Mukai
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan
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36
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Pollard RD, Fulp B, Samuel MP, Sorci-Thomas MG, Thomas MJ. The conformation of lipid-free human apolipoprotein A-I in solution. Biochemistry 2013; 52:9470-81. [PMID: 24308268 DOI: 10.1021/bi401080k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Apolipoprotein AI (apoA-I) is the principal acceptor of lipids from ATP-binding cassette transporter A1, a process that yields nascent high density lipoproteins. Analysis of lipidated apoA-I conformation yields a belt or twisted belt in which two strands of apoA-I lie antiparallel to one another. In contrast, biophysical studies have suggested that a part of lipid-free apoA-I was arranged in a four-helix bundle. To understand how lipid-free apoA-I opens from a bundle to a belt while accepting lipid it was necessary to have a more refined model for the conformation of lipid-free apoA-I. This study reports the conformation of lipid-free human apoA-I using lysine-to-lysine chemical cross-linking in conjunction with disulfide cross-linking achieved using selective cysteine mutations. After proteolysis, cross-linked peptides were verified by sequencing using tandem mass spectrometry. The resulting structure is compact with roughly four helical regions, amino acids 44-186, bundled together. C- and N-terminal ends, amino acids 1-43 and 187-243, respectively, are folded such that they lie close to one another. An unusual feature of the molecule is the high degree of connectivity of lysine40 with six other lysines, lysines that are close, for example, lysine59, to distant lysines, for example, lysine239, that are at the opposite end of the primary sequence. These results are compared and contrasted with other reported conformations for lipid-free human apoA-I and an NMR study of mouse apoA-I.
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Affiliation(s)
- Ricquita D Pollard
- Department of Biochemistry and ‡Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine , Medical Center Blvd, Winston-Salem, North Carolina 27157-1016, United States
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37
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Wang L, Mei X, Atkinson D, Small DM. Surface behavior of apolipoprotein A-I and its deletion mutants at model lipoprotein interfaces. J Lipid Res 2013; 55:478-92. [PMID: 24308948 DOI: 10.1194/jlr.m044743] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Apolipoprotein A-I (apoA-I) has a great conformational flexibility to exist in lipid-free, lipid-poor, and lipid-bound states during lipid metabolism. To address the lipid binding and the dynamic desorption behavior of apoA-I at lipoprotein surfaces, apoA-I, Δ(185-243)apoA-I, and Δ(1-59)(185-243)apoA-I were studied at triolein/water and phosphatidylcholine/triolein/water interfaces with special attention to surface pressure. All three proteins are surface active to both interfaces lowering the interfacial tension and thus increasing the surface pressure to modify the interfaces. Δ(185-243)apoA-I adsorbs much more slowly and lowers the interfacial tension less than full-length apoA-I, confirming that the C-terminal domain (residues 185-243) initiates the lipid binding. Δ(1-59)(185-243)apoA-I binds more rapidly and lowers the interfacial tension more than Δ(185-243)apoA-I, suggesting that destabilizing the N-terminal α-helical bundle (residues 1-185) restores lipid binding. The three proteins desorb from both interfaces at different surface pressures revealing that different domains of apoA-I possess different lipid affinity. Δ(1-59)(185-243)apoA-I desorbs at lower pressures compared with apoA-I and Δ(185-243)apoA-I indicating that it is missing a strong lipid association motif. We propose that during lipoprotein remodeling, surface pressure mediates the adsorption and partial or full desorption of apoA-I allowing it to exchange among different lipoproteins and adopt various conformations to facilitate its multiple functions.
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Affiliation(s)
- Libo Wang
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
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38
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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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39
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Nagao K, Hata M, Tanaka K, Takechi Y, Nguyen D, Dhanasekaran P, Lund-Katz S, Phillips MC, Saito H. The roles of C-terminal helices of human apolipoprotein A-I in formation of high-density lipoprotein particles. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:80-7. [PMID: 24120703 DOI: 10.1016/j.bbalip.2013.10.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/07/2013] [Accepted: 10/01/2013] [Indexed: 12/20/2022]
Abstract
Apolipoprotein A-I (apoA-I) accepts cholesterol and phospholipids from ATP-binding cassette transporter A1 (ABCA1)-expressing cells to form high-density lipoprotein (HDL). Human apoA-I has two tertiary structural domains and the C-terminal domain (approximately amino acids 190-243) plays a key role in lipid binding. Although the high lipid affinity region of the C-terminal domain of apoA-I (residues 223-243) is essential for the HDL formation, the function of low lipid affinity region (residues 191-220) remains unclear. To evaluate the role of residues 191-220, we analyzed the structure, lipid binding properties, and HDL formation activity of Δ191-220 apoA-I, in comparison to wild-type and Δ223-243 apoA-I. Although deletion of residues 191-220 has a slight effect on the tertiary structure of apoA-I, the Δ191-220 variant showed intermediate behavior between wild-type and Δ223-243 regarding the formation of hydrophobic sites and lipid interaction through the C-terminal domain. Physicochemical analysis demonstrated that defective lipid binding of Δ191-220 apoA-I is due to the decreased ability to form α-helix structure which provides the energetic source for lipid binding. In addition, the ability to form HDL particles in vitro and induce cholesterol efflux from ABCA1-expressing cells of Δ191-220 apoA-I was also intermediate between wild-type and Δ223-243 apoA-I. These results suggest that despite possessing low lipid affinity, residues 191-220 play a role in enhancing the ability of apoA-I to bind to and solubilize lipids by forming α-helix upon lipid interaction. Our results demonstrate that the combination of low lipid affinity region and high lipid affinity region of apoA-I is required for efficient ABCA1-dependent HDL formation.
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Affiliation(s)
- Kohjiro Nagao
- Institute of Health Biosciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan; Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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40
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Daniil G, Zannis VI, Chroni A. Effect of apoA-I Mutations in the Capacity of Reconstituted HDL to Promote ABCG1-Mediated Cholesterol Efflux. PLoS One 2013; 8:e67993. [PMID: 23826352 PMCID: PMC3694867 DOI: 10.1371/journal.pone.0067993] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/23/2013] [Indexed: 12/29/2022] Open
Abstract
ATP binding cassette transporter G1 (ABCG1) mediates the cholesterol transport from cells to high-density lipoprotein (HDL), but the role of apolipoprotein A-I (apoA-I), the main protein constituent of HDL, in this process is not clear. To address this, we measured cholesterol efflux from HEK293 cells or J774 mouse macrophages overexpressing ABCG1 using as acceptors reconstituted HDL (rHDL) containing wild-type or various mutant apoA-I forms. It was found that ABCG1-mediated cholesterol efflux was severely reduced (by 89%) when using rHDL containing the carboxyl-terminal deletion mutant apoA-I[Δ(185–243)]. ABCG1-mediated cholesterol efflux was not affected or moderately decreased by rHDL containing amino-terminal deletion mutants and several mid-region deletion or point apoA-I mutants, and was restored to 69–99% of control by double deletion mutants apoA-I[Δ(1–41)Δ(185–243)] and apoA-I[Δ(1–59)Δ(185–243)]. These findings suggest that the central helices alone of apoA-I associated to rHDL can promote ABCG1-mediated cholesterol efflux. Further analysis showed that rHDL containing the carboxyl-terminal deletion mutant apoA-I[Δ(185–243)] only slightly reduced (by 22%) the ABCG1-mediated efflux of 7-ketocholesterol, indicating that depending on the sterol type, structural changes in rHDL-associated apoA-I affect differently the ABCG1-mediated efflux of cholesterol and 7-ketocholesterol. Overall, our findings demonstrate that rHDL-associated apoA-I structural changes affect the capacity of rHDL to accept cellular cholesterol by an ABCG1-mediated process. The structure-function relationship seen here between rHDL-associated apoA-I mutants and ABCG1-mediated cholesterol efflux closely resembles that seen before in lipid-free apoA-I mutants and ABCA1-dependent cholesterol efflux, suggesting that both processes depend on the same structural determinants of apoA-I.
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Affiliation(s)
- Georgios Daniil
- Institute of Biosciences and Applications, National Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens, Greece
| | - Vassilis I. Zannis
- Molecular Genetics, Departments of Medicine and Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Angeliki Chroni
- Institute of Biosciences and Applications, National Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens, Greece
- * E-mail:
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41
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Oda MN, Budamagunta MS, Borja MS, Petrlova J, Voss JC, Lagerstedt JO. The secondary structure of apolipoprotein A-I on 9.6-nm reconstituted high-density lipoprotein determined by EPR spectroscopy. FEBS J 2013; 280:3416-24. [PMID: 23668303 PMCID: PMC3906832 DOI: 10.1111/febs.12334] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 05/09/2013] [Accepted: 05/09/2013] [Indexed: 01/09/2023]
Abstract
Apolipoprotein A-I (ApoA-I) is the major protein component of high-density lipoprotein (HDL), and is critical for maintenance of cholesterol homeostasis. During reverse cholesterol transport, HDL transitions between an array of subclasses, differing in size and composition. This process requires ApoA-I to adapt to changes in the shape of the HDL particle, transiting from an apolipoprotein to a myriad of HDL subclass-specific conformations. Changes in ApoA-I structure cause alterations in HDL-specific enzyme and receptor-binding properties, and thereby direct the HDL particle through the reverse cholesterol transport pathway. In this study, we used site-directed spin label spectroscopy to examine the conformational details of the ApoA-I central domain on HDL. The motional dynamics and accessibility to hydrophobic/hydrophilic relaxation agents of ApoA-I residues 99–163 on 9.6-nm reconstituted HDL was analyzed by EPR. In previous analyses, we examined residues 6–98 and 164–238 (of ApoA-I's 243 residues), and combining these findings with the current results, we have generated a full-length map of the backbone structure of reconstituted HDL-associated ApoA-I. Remarkably, given that the majority of ApoA-I's length is composed of amphipathic helices, we have identified nonhelical residues, specifically the presence of a β-strand (residues 149–157). The significance of these nonhelical residues is discussed, along with the other features, in the context of ApoA-I function in contrast to recent models derived by other methods.
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Affiliation(s)
- Michael N Oda
- Children's Hospital Oakland Research Institute, CA, USA
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42
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Murugesan S, Goldberg EB, Dou E, Brown WJ. Identification of diverse lipid droplet targeting motifs in the PNPLA family of triglyceride lipases. PLoS One 2013; 8:e64950. [PMID: 23741432 PMCID: PMC3669214 DOI: 10.1371/journal.pone.0064950] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Accepted: 04/19/2013] [Indexed: 12/13/2022] Open
Abstract
Members of the Patatin-like Phospholipase Domain containing Protein A (PNPLA) family play key roles in triglyceride hydrolysis, energy metabolism, and lipid droplet (LD) homoeostasis. Here we report the identification of two distinct LD targeting motifs (LTM) for PNPLA family members. Transient transfection of truncated versions of human adipose triglyceride lipase (ATGL, also known as PNPLA2), PNPLA3/adiponutrin, or PNPLA5 (GS2-like) fused to GFP revealed that the C-terminal third of these proteins contains sequences that are sufficient for targeting to LDs. Furthermore, fusing the C-termini of PNPLA3 or PNPLA5 confers LD localization to PNPLA4, which is otherwise cytoplasmic. Analyses of additional mutants in ATGL, PNPLA5, and Brummer Lipase, the Drosophila homolog of mammalian ATGL, identified two different types of LTMs. The first type, in PNPLA5 and Brummer lipase, is a set of loosely conserved basic residues, while the second type, in ATGL, is contained within a stretch of hydrophobic residues. These results show that even closely related members of the PNPLA family employ different molecular motifs to associate with LDs.
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Affiliation(s)
- Sricharan Murugesan
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Elysa B. Goldberg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Eda Dou
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - William J. Brown
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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43
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Meyers NL, Wang L, Gursky O, Small DM. Changes in helical content or net charge of apolipoprotein C-I alter its affinity for lipid/water interfaces. J Lipid Res 2013; 54:1927-38. [PMID: 23670531 DOI: 10.1194/jlr.m037531] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Amphipathic α-helices mediate binding of exchangeable apolipoproteins to lipoproteins. To probe the role of α-helical structure in protein-lipid interactions, we used oil-drop tensiometry to characterize the interfacial behavior of apolipoprotein C-I (apoC-I) variants at triolein/water (TO/W) and 1-palmitoyl-2-oleoylphosphatidylcholine/triolein/water (POPC/TO/W) interfaces. ApoC-I, the smallest apolipoprotein, has two amphipathic α-helices. Mutants had single Pro or Ala substitutions that resulted in large differences in helical content in solution and on phospholipids. The ability of apoC-I to bind TO/W and POPC/TO/W interfaces correlated strongly with α-helical propensity. On binding these interfaces, peptides with higher helical propensity increased surface pressure to a greater extent. Likewise, peptide exclusion pressure at POPC/TO/W interfaces increased with greater helical propensity. ApoC-I retention on TO/W and POPC/TO/W interfaces correlated strongly with phospholipid-bound helical content. On compression of these interfaces, peptides with higher helical content were ejected at higher pressures. Substitution of Arg for Pro in the N-terminal α-helix altered net charge and reduced apoC-I affinity for POPC/TO/W interfaces. Our results suggest that peptide-lipid interactions drive α-helix binding to and retention on lipoproteins. Point mutations in small apolipoproteins could significantly change α-helical propensity or charge, thereby disrupting protein-lipid interactions and preventing the proteins from regulating lipoprotein catabolism at high surface pressures.
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Affiliation(s)
- Nathan L Meyers
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, USA
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44
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Smith LE, Segrest JP, Davidson WS. Helical domains that mediate lipid solubilization and ABCA1-specific cholesterol efflux in apolipoproteins C-I and A-II. J Lipid Res 2013; 54:1939-48. [PMID: 23620136 DOI: 10.1194/jlr.m037903] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Many of the apolipoproteins in HDL can elicit cholesterol efflux via ABCA1, a critical initial step in HDL formation. Recent work has indicated that omnipresent amphipathic helices play a critical role, and these have been studied intensively in the most common HDL protein, apolipoprotein (apo)A-I. However, little information exists about helical domain arrangement in other apolipoproteins. We studied two of the smallest apolipoproteins known to interact with ABCA1, human apoA-II and apoC-I, in terms of ability to reorganize phospholipid (PL) bilayers and to promote ABCA1-mediated cholesterol. We found that both proteins contained helical domains that were fast and slow with respect to solubilizing PL. ABCA1-medated efflux required a minimum of a bihelical polypeptide comprised of at least one each of a slow and fast lipid reorganizing domain. In both proteins, the fast helix was located at the C terminus preceded by a slow helix. Helical placement in apoC-I was not critical for ABCA1 activity, but helix swaps in apoA-II dramatically disrupted cholesterol efflux, indicating that the tertiary structure of the longer apolipoprotein is important for the pathway. This work has implications for a more complete molecular understanding of apolipoprotein-mediated cholesterol efflux.
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Affiliation(s)
- Loren E Smith
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH, USA
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Zhang T, Xie N, He W, Liu R, Lei Y, Chen Y, Tang H, Liu B, Huang C, Wei Y. An integrated proteomics and bioinformatics analyses of hepatitis B virus X interacting proteins and identification of a novel interactor apoA-I. J Proteomics 2013; 84:92-105. [PMID: 23568022 DOI: 10.1016/j.jprot.2013.03.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 03/01/2013] [Accepted: 03/12/2013] [Indexed: 02/05/2023]
Abstract
UNLABELLED HBx is well-known to be a multifunctional protein encoded by HBV and its biological functions are mainly dependent on pleiotropic protein-protein interactions (PPIs); however, the global mapping of HBx-interactome has not been established so far. Thus, in this study, we have identified 127 HBx-interacting proteins by a profound GST pull-down assay coupled with mass spectrometry, and constructed an HBx-interactome network and core apoA-I pathways with a series of bioinformatics approaches. One of the identified HBx-binding partners is apolipoprotein A-I (apoA-I), which has a specific role in lipid and cholesterol metabolism. The HBx-apoA-I protein interaction was confirmed by both GST pull-down and co-immunoprecipitation. The ectopic overexpression of apoA-I can lead to a significant inhibition on HBV secretion concomitant with the reduction of cellular cholesterol level. In addition, HBV can modulate the function of apoA-I through HBx which might interact with the 44-189 residues of apoA-I and result in dysfunction of apoA-I such as decreased self-association ability, increased carbonyl level and impaired lipid-binding ability. Our results demonstrate an integrated physical association of HBx and host proteins, especially a novel interactor apoA-I that may influence the HBV secretion, which would shed new light on exploring the complicated mechanisms of HBV manipulation on host cellular functions. BIOLOGICAL SIGNIFICANCE HBx is well-known to be a multifunctional protein encoded by HBV and its biological functions are mainly dependent on pleiotropic protein-protein interactions. Although a series of HBx-interacting proteins have been identified, a global characterization of HBx interactome has not been reported. In this study, we have identified a total of 127 HBx-interacting proteins by a profound GST pull-down assay coupled with mass spectrometry, and constructed an HBx-interactome network with a series of bioinformatics approaches. Our results demonstrate an integrated physical association of HBx and host proteins which may help us explore the complicated mechanisms of HBV manipulation on host cellular functions. In addition, we validated one of the identified HBx-binding partners, apolipoprotein A-I (apoA-I), which played a significant inhibitory effect on HBV secretion, indicating a crucial role of the HBx-apoA-I axis in HBV life cycle.
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Affiliation(s)
- Tao Zhang
- The State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PR China
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46
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Dalla-Riva J, Stenkula KG, Petrlova J, Lagerstedt JO. Discoidal HDL and apoA-I-derived peptides improve glucose uptake in skeletal muscle. J Lipid Res 2013; 54:1275-82. [PMID: 23471027 PMCID: PMC3653404 DOI: 10.1194/jlr.m032904] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Lipid-free apoA-I and mature spherical HDL have been shown to induce glucose uptake in skeletal muscle. To exploit apoA-I and HDL states for diabetes therapy, further understanding of interaction between muscle and apoA-I is required. This study has examined whether nascent discoidal HDL, in which apoA-I attains a different conformation from mature HDL and lipid-free states, could induce muscle glucose uptake and whether a specific domain of apoA-I can mediate this effect. Using L6 myotubes stimulated with synthetic reconstituted discoidal HDL (rHDL), we show a glucose uptake effect comparable to insulin. Increased plasma membrane GLUT4 levels in ex vivo rHDL-stimulated myofibers from HA-GLUT4-GFP transgenic mice support this observation. rHDL increased phosphorylation of AMP kinase (AMPK) and acetyl-coA carboxylase (ACC) but not Akt. A survey of domain-specific peptides of apoA-I showed that the lipid-free C-terminal 190-243 fragment increases plasma membrane GLUT4, promotes glucose uptake, and activates AMPK signaling but not Akt. This may be explained by changes in α-helical content of 190-243 fragment versus full-length lipid-free apoA-I as assessed by circular dichroism spectroscopy. Discoidal HDL and the 190-243 peptide of apoA-I are potent agonists of glucose uptake in skeletal muscle, and the C-terminal α-helical content of apoA-I may be an important determinant of this effect.
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Affiliation(s)
- Jonathan Dalla-Riva
- Department of Experimental Medical Science, Lund University, S-221 84 Lund, Sweden
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47
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Phillips MC. New insights into the determination of HDL structure by apolipoproteins: Thematic review series: high density lipoprotein structure, function, and metabolism. J Lipid Res 2012; 54:2034-2048. [PMID: 23230082 DOI: 10.1194/jlr.r034025] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Apolipoprotein (apo)A-I is the principal protein component of HDL, and because of its conformational adaptability, it can stabilize all HDL subclasses. The amphipathic α-helix is the structural motif that enables apoA-I to achieve this functionality. In the lipid-free state, the helical segments unfold and refold in seconds and are located in the N-terminal two thirds of the molecule where they are loosely packed as a dynamic, four-helix bundle. The C-terminal third of the protein forms an intrinsically disordered domain that mediates initial binding to phospholipid surfaces, which occurs with coupled α-helix formation. The lipid affinity of apoA-I confers detergent-like properties; it can solubilize vesicular phospholipids to create discoidal HDL particles with diameters of approximately 10 nm. Such particles contain a segment of phospholipid bilayer and are stabilized by two apoA-I molecules that are arranged in an anti-parallel, double-belt conformation around the edge of the disc, shielding the hydrophobic phospholipid acyl chains from exposure to water. The apoA-I molecules are in a highly dynamic state, and they stabilize discoidal particles of different sizes by certain segments forming loops that detach reversibly from the particle surface. The flexible apoA-I molecule adapts to the surface of spherical HDL particles by bending and forming a stabilizing trefoil scaffold structure. The above characteristics of apoA-I enable it to partner with ABCA1 in mediating efflux of cellular phospholipid and cholesterol and formation of a heterogeneous population of nascent HDL particles. Novel insights into the structure-function relationships of apoA-I should help reveal mechanisms by which HDL subclass distribution can be manipulated.
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Affiliation(s)
- Michael C Phillips
- Lipid Research Group, Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
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48
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Mizuguchi C, Hata M, Dhanasekaran P, Nickel M, Phillips MC, Lund-Katz S, Saito H. Fluorescence analysis of the lipid binding-induced conformational change of apolipoprotein E4. Biochemistry 2012; 51:5580-8. [PMID: 22730894 DOI: 10.1021/bi300672s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apolipoprotein (apo) E is thought to undergo conformational changes in the N-terminal helix bundle domain upon lipid binding, modulating its receptor binding activity. In this study, site-specific fluorescence labeling of the N-terminal (S94) and C-terminal (W264 or S290) helices in apoE4 by pyrene maleimide or acrylodan was employed to probe the conformational organization and lipid binding behavior of the N- and C-terminal domains. Guanidine denaturation experiments monitored by acrylodan fluorescence demonstrated the less organized, more solvent-exposed structure of the C-terminal helices compared to the N-terminal helix bundle. Pyrene excimer fluorescence together with gel filtration chromatography indicated that there are extensive intermolecular helix-helix contacts through the C-terminal helices of apoE4. Comparison of increases in pyrene fluorescence upon binding of pyrene-labeled apoE4 to egg phosphatidylcholine small unilamellar vesicles suggests a two-step lipid-binding process; apoE4 initially binds to a lipid surface through the C-terminal helices followed by the slower conformational reorganization of the N-terminal helix bundle domain. Consistent with this, fluorescence resonance energy transfer measurements from Trp residues to acrylodan attached at position 94 demonstrated that upon binding to the lipid surface, opening of the N-terminal helix bundle occurs at the same rate as the increase in pyrene fluorescence of the N-terminal domain. Such a two-step mechanism of lipid binding of apoE4 is likely to apply to mostly phospholipid-covered lipoproteins such as VLDL. However, monitoring pyrene fluorescence upon binding to HDL(3) suggests that not only apoE-lipid interactions but also protein-protein interactions are important for apoE4 binding to HDL(3).
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Affiliation(s)
- Chiharu Mizuguchi
- 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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49
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Biocompatibility of mannan nanogel—safe interaction with plasma proteins. Biochim Biophys Acta Gen Subj 2012; 1820:1043-51. [DOI: 10.1016/j.bbagen.2012.04.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 04/12/2012] [Accepted: 04/16/2012] [Indexed: 11/19/2022]
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50
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Rahaman H, Zhou S, Dodia C, Feinstein SI, Huang S, Speicher D, Fisher AB. Increased phospholipase A2 activity with phosphorylation of peroxiredoxin 6 requires a conformational change in the protein. Biochemistry 2012; 51:5521-30. [PMID: 22663767 DOI: 10.1021/bi300380h] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We have shown previously and confirmed in this study that the phospholipase A(2) (PLA(2)) activity of peroxiredoxin 6 (Prdx6) is markedly increased by phosphorylation. This report evaluates the conformation and thermodynamic stability of Prdx6 protein after phosphorylation to understand the physical basis for increased activity. Phosphorylation resulted in decreased negative far-UV CD, strengthened ANS binding, and a lack of rigid tertiary structure, compatible with a change in conformation to that of a molten globule. The ΔG°(D) was 3.3 ± 0.3 kcal mol(-1) for Prdx6 and 1.7 ± 0.7 kcal mol(-1) for pPrdx6, suggesting that phosphorylation destabilizes the protein. Phosphorylation of Prdx6 changed the conformation of the N-terminal domain exposing Trp 33, as determined by tryptophan fluorescence and NaI fluorescence quenching. The kinetics of interaction of proteins with unilamellar liposomes (50:25:15:10 DPPC:egg PC:cholesterol:PG molar ratio) were evaluated with tryptophan fluorescence. pPrdx6 bound to liposomes with a higher affinity (K(d) = 5.6 ± 1.2 μM) than Prdx6 (K(d) = 24.9 ± 4.5 μM). By isothermal titration calorimetry, pPrdx6 bound to liposomes with a large exothermic heat loss (ΔH = -31.49 ± 0.22 kcal mol(-1)). Correlating our conformational studies with the published crystal structure of oxidized Prdx6 suggests that phosphorylation results in exposure of hydrophobic residues, thereby providing accessibility to the sites for liposome binding. Because binding of the enzyme to the phospholipid substrate interface is a requirement for PLA(2) activity, these results indicate that a change in the conformation of Prdx6 upon its phosphorylation is the basis for enhancement of PLA(2) enzymatic activity.
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Affiliation(s)
- Hamidur Rahaman
- Institute for Environmental Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6068, United States
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