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Arai H, Kono N. α-Tocopherol transfer protein (α-TTP). Free Radic Biol Med 2021; 176:162-175. [PMID: 34563650 DOI: 10.1016/j.freeradbiomed.2021.09.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/01/2021] [Accepted: 09/03/2021] [Indexed: 10/20/2022]
Abstract
α-Tocopherol transfer protein (α-TTP) is so far the only known protein that specifically recognizes α-tocopherol (α-Toc), the most abundant and most biologically active form of vitamin E, in higher animals. α-TTP is highly expressed in the liver where α-TTP selects α-Toc among vitamin E forms taken up via plasma lipoproteins and promotes its secretion to circulating lipoproteins. Thus, α-TTP is a major determinant of plasma α-Toc concentrations. Familial vitamin E deficiency, also called Ataxia with vitamin E deficiency, is caused by mutations in the α-TTP gene. More than 20 different mutations have been found in the α-TTP gene worldwide, among which some missense mutations provided valuable clues to elucidate the molecular mechanisms underlying intracellular α-Toc transport. In hepatocytes, α-TTP catalyzes the vectorial transport of α-Toc from the endocytotic compartment to the plasma membrane (PM) by targeting phosphatidylinositol phosphates (PIPs) such as PI(4,5)P2. By binding PIPs at the PM, α-TTP opens the lid covering the hydrophobic pocket, thus facilitating the release of bound α-Toc to the PM.
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Affiliation(s)
- Hiroyuki Arai
- Laboratory of Microenvironmental and Metabolic Health Science, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Nozomu Kono
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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2
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Aeschimann W, Kammer S, Staats S, Schneider P, Schneider G, Rimbach G, Cascella M, Stocker A. Engineering of a functional γ-tocopherol transfer protein. Redox Biol 2020; 38:101773. [PMID: 33197771 PMCID: PMC7677715 DOI: 10.1016/j.redox.2020.101773] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 11/28/2022] Open
Abstract
α-tocopherol transfer protein (TTP) was previously reported to self-aggregate into 24-meric spheres (α-TTPS) and to possess transcytotic potency across mono-layers of human umbilical vein endothelial cells (HUVECs). In this work, we describe the characterisation of a functional TTP variant with its vitamer selectivity shifted towards γ-tocopherol. The shift was obtained by introducing an alanine to leucine substitution into the substrate-binding pocket at position 156 through site directed mutagenesis. We report here the X-ray crystal structure of the γ-tocopherol specific particle (γ-TTPS) at 2.24 Å resolution. γ-TTPS features full functionality compared to its α-tocopherol specific parent including self-aggregation potency and transcytotic activity in trans-well experiments using primary HUVEC cells. The impact of the A156L mutation on TTP function is quantified in vitro by measuring the affinity towards γ-tocopherol through micro-differential scanning calorimetry and by determining its ligand-transfer activity. Finally, cell culture experiments using adherently grown HUVEC cells indicate that the protomers of γ-TTP, in contrast to α-TTP, do not counteract cytokine-mediated inflammation at a transcriptional level. Our results suggest that the A156L substitution in TTP is fully functional and has the potential to pave the way for further experiments towards the understanding of α-tocopherol homeostasis in humans.
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Affiliation(s)
- Walter Aeschimann
- University of Bern, Department of Chemistry and Biochemistry, Bern, 3012, Switzerland
| | - Stephan Kammer
- University of Bern, Department of Chemistry and Biochemistry, Bern, 3012, Switzerland
| | - Stefanie Staats
- University of Kiel, Institute of Human Nutrition and Food Science, Kiel, 24118, Germany
| | - Petra Schneider
- Institute of Pharmaceutical Sciences, ETH Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Gisbert Schneider
- Institute of Pharmaceutical Sciences, ETH Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Gerald Rimbach
- University of Kiel, Institute of Human Nutrition and Food Science, Kiel, 24118, Germany
| | - Michele Cascella
- University of Oslo, Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, PO Box 1033 Blindern, 0315, Oslo, Norway
| | - Achim Stocker
- University of Bern, Department of Chemistry and Biochemistry, Bern, 3012, Switzerland.
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Tamura T, Otulakowski G, Kavanagh BP. Could nanotechnology make vitamin E therapeutically effective? Am J Physiol Lung Cell Mol Physiol 2018; 316:L1-L5. [PMID: 30407864 DOI: 10.1152/ajplung.00430.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Vitamin E (VitE) has important antioxidant and anti-inflammatory effects and is necessary for normal physiological function. α-Tocopherol (α-T), the predominant form of VitE in human tissues, has been extensively studied. Other VitE forms, particularly γ-tocopherol (γ-T), are also potent bioactive molecules. The effects are complex, involving both reactive oxygen and nitrogen species, but trials of VitE have been generally negative. We propose that a nanoparticle approach to delivery of VitE might provide effective delivery and therapeutic effect.
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Affiliation(s)
- Tetsuya Tamura
- Program in Translational Medicine, The Research Institute, and the Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto , Toronto , Canada
| | - Gail Otulakowski
- Program in Translational Medicine, The Research Institute, and the Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto , Toronto , Canada
| | - Brian P Kavanagh
- Program in Translational Medicine, The Research Institute, and the Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto , Toronto , Canada
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Aeschimann W, Staats S, Kammer S, Olieric N, Jeckelmann JM, Fotiadis D, Netscher T, Rimbach G, Cascella M, Stocker A. Self-assembled α-Tocopherol Transfer Protein Nanoparticles Promote Vitamin E Delivery Across an Endothelial Barrier. Sci Rep 2017; 7:4970. [PMID: 28694484 PMCID: PMC5504013 DOI: 10.1038/s41598-017-05148-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/24/2017] [Indexed: 01/16/2023] Open
Abstract
Vitamin E is one of the most important natural antioxidants, protecting polyunsaturated fatty acids in the membranes of cells. Among different chemical isoforms assimilated from dietary regimes, RRR-α-tocopherol is the only one retained in higher animals. This is possible thanks to α-Tocopherol Transfer Protein (α-TTP), which extracts α-tocopherol from endosomal compartments in liver cells, facilitating its distribution into the body. Here we show that, upon binding to its substrate, α-TTP acquires tendency to aggregation into thermodynamically stable high molecular weight oligomers. Determination of the structure of such aggregates by X-ray crystallography revealed a spheroidal particle formed by 24 protein monomers. Oligomerization is triggered by refolding of the N-terminus. Experiments with cultured cell monolayers demonstrate that the same oligomers are efficiently transported through an endothelial barrier (HUVEC) and not through an epithelial one (Caco-2). Discovery of a human endogenous transport protein with intrinsic capability of crossing endothelial tissues opens to new ways of drug delivery into the brain or other tissues protected by endothelial barriers.
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Affiliation(s)
- Walter Aeschimann
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
| | - Stefanie Staats
- University of Kiel, Institute of Human Nutrition and Food Science, Kiel, Germany
| | - Stephan Kammer
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
| | | | - Jean-Marc Jeckelmann
- University of Bern, Institute of Biochemistry and Molecular Medicine, Bern, Switzerland
| | - Dimitrios Fotiadis
- University of Bern, Institute of Biochemistry and Molecular Medicine, Bern, Switzerland
| | | | - Gerald Rimbach
- University of Kiel, Institute of Human Nutrition and Food Science, Kiel, Germany
| | - Michele Cascella
- University of Oslo, Department of Chemistry and Centre for Theoretical and Computational Chemistry (CTCC), Oslo, Norway.
| | - Achim Stocker
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland.
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Cortopassi WA, Kumar K, Paton RS. Cation–π interactions in CREBBP bromodomain inhibition: an electrostatic model for small-molecule binding affinity and selectivity. Org Biomol Chem 2016; 14:10926-10938. [DOI: 10.1039/c6ob02234k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A new model is presented to explain and predict binding affinity of aromatic and heteroaromatic ligands for the CREBBP bromodomain based on cation–π interaction strength.
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Affiliation(s)
| | - Kiran Kumar
- Chemistry Research Laboratory
- University of Oxford
- Oxford OX1 3TA
- UK
| | - Robert S. Paton
- Chemistry Research Laboratory
- University of Oxford
- Oxford OX1 3TA
- UK
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Bergsdorf C, Fiez-Vandal C, Sykes DA, Bernet P, Aussenac S, Charlton SJ, Schopfer U, Ottl J, Duckely M. An Alternative Thiol-Reactive Dye to Analyze Ligand Interactions with the Chemokine Receptor CXCR2 Using a New Thermal Shift Assay Format. ACTA ACUST UNITED AC 2015; 21:243-51. [DOI: 10.1177/1087057115619597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 10/29/2015] [Indexed: 11/16/2022]
Abstract
Integral membrane proteins (IMPs) play an important role in many cellular events and are involved in numerous pathological processes. Therefore, understanding the structure and function of IMPs is a crucial prerequisite to enable successful targeting of these proteins with low molecular weight (LMW) ligands early on in the discovery process. To optimize IMP purification/crystallization and to identify/characterize LMW ligand-target interactions, robust, reliable, high-throughput, and sensitive biophysical methods are needed. Here, we describe a differential scanning fluorimetry (DSF) screening method using the thiol-reactive BODIPY FL-cystine dye to monitor thermal unfolding of the G-protein-coupled receptor (GPCR), CXCR2. To validate this method, the seven-transmembrane protein CXCR2 was analyzed with a set of well-characterized antagonists. This study showed that the new DSF assay assessed reliably the stability of CXCR2 in a 384-well format. The analysis of 14 ligands with a potency range over 4 log units demonstrated the detection/characterization of LMW ligands binding to the membrane protein target. Furthermore, DSF results cross-validated with the label-free differential static light scattering (DSLS) thermal denaturation method. These results underline the potential of the BODIPY assay format as a general tool to investigate membrane proteins and their interaction partners.
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Affiliation(s)
- Christian Bergsdorf
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
| | - Cédric Fiez-Vandal
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
- Current affiliation: Heptares Therapeutics Ltd, BioPark, Welwyn Garden City, Hertfordshire, UK
| | - David A. Sykes
- Novartis Institutes for BioMedical Research (NIBR), Respiratory Diseases, Horsham, UK
- Current affiliation: School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
| | - Pascal Bernet
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
| | - Sonia Aussenac
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
- Current affiliation: Novartis Pharma, Basel, Switzerland
| | - Steven J. Charlton
- Novartis Institutes for BioMedical Research (NIBR), Respiratory Diseases, Horsham, UK
- Current affiliation: School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, UK
| | - Ulrich Schopfer
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
| | - Johannes Ottl
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
| | - Myriam Duckely
- Novartis Institutes for BioMedical Research (NIBR), Center for Proteomic Chemistry, Switzerland
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Lamprakis C, Stocker A, Cascella M. Mechanisms of recognition and binding of α-TTP to the plasma membrane by multi-scale molecular dynamics simulations. Front Mol Biosci 2015; 2:36. [PMID: 26191529 PMCID: PMC4487086 DOI: 10.3389/fmolb.2015.00036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/15/2015] [Indexed: 12/12/2022] Open
Abstract
We used multiple sets of simulations both at the atomistic and coarse-grained level of resolution to investigate interaction and binding of α-tochoperol transfer protein (α-TTP) to phosphatidylinositol phosphate lipids (PIPs). Our calculations indicate that enrichment of membranes with such lipids facilitate membrane anchoring. Atomistic models suggest that PIP can be incorporated into the binding cavity of α-TTP and therefore confirm that such protein can work as lipid exchanger between the endosome and the plasma membrane. Comparison of the atomistic models of the α-TTP-PIPs complex with membrane-bound α-TTP revealed different roles for the various basic residues composing the basic patch that is key for the protein/ligand interaction. Such residues are of critical importance as several point mutations at their position lead to severe forms of ataxia with vitamin E deficiency (AVED) phenotypes. Specifically, R221 is main residue responsible for the stabilization of the complex. R68 and R192 exchange strong interactions in the protein or in the membrane complex only, suggesting that the two residues alternate contact formation, thus facilitating lipid flipping from the membrane into the protein cavity during the lipid exchange process. Finally, R59 shows weaker interactions with PIPs anyway with a clear preference for specific phosphorylation positions, hinting a role in early membrane selectivity for the protein. Altogether, our simulations reveal significant aspects at the atomistic scale of interactions of α-TTP with the plasma membrane and with PIP, providing clarifications on the mechanism of intracellular vitamin E trafficking and helping establishing the role of key residue for the functionality of α-TTP.
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Affiliation(s)
- Christos Lamprakis
- Department of Chemistry and Biochemistry, University of Bern Bern, Switzerland
| | - Achim Stocker
- Department of Chemistry and Biochemistry, University of Bern Bern, Switzerland
| | - Michele Cascella
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Oslo Oslo, Norway
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Structural insights on cholesterol endosynthesis: Binding of squalene and 2,3-oxidosqualene to supernatant protein factor. J Struct Biol 2015; 190:261-70. [DOI: 10.1016/j.jsb.2015.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 05/08/2015] [Accepted: 05/11/2015] [Indexed: 11/24/2022]
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9
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Liu K, Luo HL, Zuo ZY, Jia HN, Zhang YW, Chang YF, Jiao LJ. Regulation of sheep α-TTP by dietary vitamin E and preparation of monoclonal antibody for sheep α-TTP. Gene 2014; 540:110-6. [DOI: 10.1016/j.gene.2014.02.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 01/31/2014] [Accepted: 02/25/2014] [Indexed: 01/05/2023]
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Helbling RE, Bolze CS, Golczak M, Palczewski K, Stocker A, Cascella M. Cellular retinaldehyde binding protein-different binding modes and micro-solvation patterns for high-affinity 9-cis- and 11-cis-retinal substrates. J Phys Chem B 2013; 117:10719-29. [PMID: 23964907 DOI: 10.1021/jp405410t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We use molecular dynamics (MD) simulations to determine the binding properties of different retinoid species to cellular retinaldehyde binding protein (CRALBP). The complexes formed by 9-cis-retinal or 11-cis-retinal bound to both the native protein and the R234W mutant, associated to Bothnia-retina dystrophy, are investigated. The presented studies are also complemented by analysis of the binding structures of the CRALBP/9-cis-retinol and CRALBP/9,13-dicis-retinal complexes. We find that the poor X-ray scattering properties of the polyene tail of the ligand in all wild-type complexes can be attributed to a high mobility of this region, which does not localize in a single binding conformation even at very low temperatures. Our simulations report a clear difference in the residual solvation pattern in CRALBP complexes with either 9-cis- or 9,13-dicis-retinal. The reported structures indicate that the microsolvation properties of the ligand are the key structural element triggering the very recently discovered isomerase activity of this protein. The binding geometries obtained by MD simulations are validated by calculation of the respective optical spectra by the ZINDO/S semiempirical method, which can reproduce with good qualitative agreement the different red-shifts of the first absorption band of the different complexes.
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Affiliation(s)
- Rachel E Helbling
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, 3012 Bern, Switzerland
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