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Tatulian SA, Kandel N. Membrane Pore Formation by Peptides Studied by Fluorescence Techniques. Methods Mol Biol 2019; 2003:449-464. [PMID: 31218629 DOI: 10.1007/978-1-4939-9512-7_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pore formation in cellular membranes by pathogen-derived proteins is a mechanism utilized by a set of microbes to exert their cytotoxic effect. On the other hand, the host cells have developed a defense mechanism to produce antimicrobial peptides to kill the pathogens by a similar, membrane perforation mechanism. Furthermore, certain endogenous proteins or peptides kill the parent cells through membrane permeabilization. Analysis of the molecular details of membrane pore formation is often conducted using artificial systems, such as bilayer lipid membranes and synthetic peptides. This chapter describes two fluorescence-based methods to study peptide-induced membrane leakage. One method involves preparation of lipid vesicles loaded with a fluorophore (e.g., calcein or carboxyfluorescein) at a self-quenching concentration. If the externally added peptide forms relatively large pores (≥1 nm in diameter), the fluorophore leaks out and undergoes dequenching, resulting in time-dependent increase in fluorescence. The other method is designed to monitor smaller pores (<1 nm in diameter). It involves preparation of vesicles in a Ca2+-less buffer, containing a Ca2+-dependent fluorophore, such as Quin-2. Removal of external Quin-2 by a desalting column and addition of an appropriate concentration of CaCl2 externally sequesters Quin-2 and Ca2+ ions by the vesicle membrane. Addition of the pore-forming peptide to these vesicles results in membrane permeabilization, Ca2+ influx and binding to Quin-2. In both cases, the kinetics of the increase of fluorescence and its equilibrium levels allow quantitative analysis of the pore formation mechanism.
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Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, FL, USA.
| | - Nabin Kandel
- Department of Physics, University of Central Florida, Orlando, FL, USA
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Lai YC, Li CC, Sung TC, Chang CW, Lan YJ, Chiang YW. The role of cardiolipin in promoting the membrane pore-forming activity of BAX oligomers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:268-280. [PMID: 29958826 DOI: 10.1016/j.bbamem.2018.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/17/2018] [Accepted: 06/22/2018] [Indexed: 01/31/2023]
Abstract
BCL-2-associated X (BAX) protein acts as a gatekeeper in regulating mitochondria-dependent apoptosis. Under cellular stress, BAX becomes activated and transforms into a lethal oligomer that causes mitochondrial outer membrane permeabilization (MOMP). Previous studies have identified several structural features of the membrane-associated BAX oligomer; they include the formation of the BH3-in-groove dimer, the collapse of the helical hairpin α5-α6, and the membrane insertion of α9 helix. However, it remains unclear as to the role of lipid environment in determining the conformation and the pore-forming activity of the BAX oligomers. Here we study molecular details of the membrane-associated BAX in various lipid environments using fluorescence and ESR techniques. We identify the inactive versus active forms of membrane-associated BAX, only the latter of which can induce stable and large membrane pores that are sufficient in size to pass apoptogenic factors. We reveal that the presence of CL is crucial to promoting the association between BAX dimers, hence the active oligomers. Without the presence of CL, BAX dimers assemble into an inactive oligomer that lacks the ability to form stable pores in the membrane. This study suggests an important role of CL in determining the formation of active BAX oligomers.
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Affiliation(s)
- Yei-Chen Lai
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chieh-Chin Li
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Tai-Ching Sung
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chia-Wei Chang
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yu-Jing Lan
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
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A novel family of mammalian transmembrane proteins involved in cholesterol transport. Sci Rep 2017; 7:7450. [PMID: 28785058 PMCID: PMC5547113 DOI: 10.1038/s41598-017-07077-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/22/2017] [Indexed: 11/20/2022] Open
Abstract
Cholesterol is an essential compound in mammalian cells because it is involved in a wide range of functions, including as a key component of membranes, precursor of important molecules such as hormones, bile acids and vitamin D. The cholesterol transport across the circulatory system is a well-known process in contrast to the intracellular cholesterol transport, which is poorly understood. Recently in our laboratory, we identified a novel protein in C. elegans involved in dietary cholesterol uptake, which we have named ChUP-1. Insillicoanalysis identified two putative orthologue candidate proteins in mammals. The proteins SIDT1 and SIDT2 share identity and conserved cholesterol binding (CRAC) domains with C. elegans ChUP-1. Both mammalian proteins are annotated as RNA transporters in databases. In the present study, we show evidence indicating that SIDT1 and SIDT2 not only do not transport RNA, but they are involved in cholesterol transport. Furthermore, we show that single point mutations directed to disrupt the CRAC domains of both proteins prevent FRET between SIDT1 and SIDT2 and the cholesterol analogue dehydroergosterol (DHE) and alter cholesterol transport.
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Karageorgis A, Claron M, Jugé R, Aspord C, Thoreau F, Leloup C, Kucharczak J, Plumas J, Henry M, Hurbin A, Verdié P, Martinez J, Subra G, Dumy P, Boturyn D, Aouacheria A, Coll JL. Systemic Delivery of Tumor-Targeted Bax-Derived Membrane-Active Peptides for the Treatment of Melanoma Tumors in a Humanized SCID Mouse Model. Mol Ther 2017; 25:534-546. [PMID: 28153100 DOI: 10.1016/j.ymthe.2016.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 01/03/2023] Open
Abstract
Melanoma is a highly metastatic and deadly form of cancer. Invasive melanoma cells overexpress integrin αvβ3, which is a well-known target for Arg-Gly-Asp-based (RGD) peptides. We developed a sophisticated method to synthetize milligram amounts of a targeted vector that allows the RGD-mediated targeting, internalization, and release of a mitochondria-disruptive peptide derived from the pro-apoptotic Bax protein. We found that 2.5 μM Bax[109-127] was sufficient to destabilize the mitochondria in ten different tumor cell lines, even in the presence of the anti-apoptotic Bcl2 protein, which is often involved in tumor resistance. This pore-forming peptide displayed antitumor activity when it was covalently linked by a disulfide bridge to the tetrameric RAFT-c[RGD]4-platform and after intravenous injection in a human melanoma tumor model established in humanized immuno-competent mice. In addition to its direct toxic effect, treatment with this combination induced the release of the immuno-stimulating factor monocyte chimoattractant protein 1 (MCP1) in the blood and a decrease in the level of the pro-angiogenic factor FGF2. Our novel multifunctional, apoptosis-inducing agent could be further customized and assayed for potential use in tumor-targeted therapy.
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Affiliation(s)
- Anastassia Karageorgis
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Michaël Claron
- Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Romain Jugé
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - Caroline Aspord
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Fabien Thoreau
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Claire Leloup
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Jérôme Kucharczak
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - Joël Plumas
- Université Grenoble Alpes, 38000 Grenoble, France; EMR EFS-UGA-INSERM U1209- CNRS, Immunobiology and Immunotherapy of Chronic Diseases, 38706 La Tronche, France; EFS Rhone-Alpes, R&D Laboratory, 38701 La Tronche, France
| | - Maxime Henry
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Amandine Hurbin
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France
| | - Pascal Verdié
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Jean Martinez
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Gilles Subra
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Pascal Dumy
- CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France; CNRS UMR 5247, Institut des Biomolécules Max Mousseron IBMM, 34095 Montpellier, France
| | - Didier Boturyn
- Université Grenoble Alpes, 38000 Grenoble, France; CNRS UMR 5250, ICMG FR2607, 38000 Grenoble, France
| | - Abdel Aouacheria
- Molecular Biology of the Cell Laboratory (LBMC), Ecole Normale Supérieure de Lyon, UMR 5239 CNRS - UCBL - ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Institut des Sciences de l'Evolution de Montpellier (ISEM), UMR 5554, Université de Montpellier, CNRS, IRD, EPHE, Place Eugène Bataillon, 34095 Montpellier, France.
| | - Jean-Luc Coll
- INSERM U1209, Institut Albert Bonniot, 38706 La Tronche, France; Université Grenoble Alpes, 38000 Grenoble, France.
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Effect of the CRAC Peptide, VLNYYVW, on mPTP Opening in Rat Brain and Liver Mitochondria. Int J Mol Sci 2016; 17:ijms17122096. [PMID: 27983605 PMCID: PMC5187896 DOI: 10.3390/ijms17122096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 12/01/2016] [Accepted: 12/07/2016] [Indexed: 01/08/2023] Open
Abstract
The translocator protein (TSPO; 18 kDa) is a high-affinity cholesterol-binding protein located in the outer membrane of mitochondria. A domain in the C-terminus of TSPO was characterized as the cholesterol recognition/interaction amino acid consensus (CRAC). The ability of the CRAC domain to bind to cholesterol led us to hypothesize that this peptide may participate in the regulation of mitochondrial membrane permeability. Herein, we report the effect of the synthetic CRAC peptide, VLNYYVW, on mitochondrial permeability transition pore (mPTP) opening. It was found that the CRAC peptide alone prevents the mPTP from opening, as well as the release of apoptotic factors (cytochrome c, AIF, and EndoG) in rat brain mitochondria (RBM). Co-incubation of CRAC, together with the TSPO drug ligand, PK 11195, resulted in the acceleration of mPTP opening and in the increase of apoptotic factor release. VLNYYVW did not induce swelling in rat liver mitochondria (RLM). 3,17,19-androsten-5-triol (19-Atriol; an inhibitor of the cholesterol-binding activity of the CRAC peptide) alone and in combination with the peptide was able to stimulate RLM swelling, which was Ca2+- and CsA-sensitive. Additionally, a combination of 19-Atriol with 100 nM PK 11195 or with 100 µM PK 11195 displayed the opposite effect: namely, the addition of 19-Atriol with 100 µM PK 11195 in a suspension of RLM suppressed the Ca2+-induced swelling of RLM by 40%, while the presence of 100 nM PK 11195 with 19-Atriol enhanced the swelling of RLM by 60%. Taken together, these data suggest the participation of the TSPO’s CRAC domain in the regulation of permeability transition.
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Luna-Vargas MPA, Chipuk JE. Physiological and Pharmacological Control of BAK, BAX, and Beyond. Trends Cell Biol 2016; 26:906-917. [PMID: 27498846 DOI: 10.1016/j.tcb.2016.07.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 01/01/2023]
Abstract
Cellular commitment to the mitochondrial pathway of apoptosis is accomplished when proapoptotic B cell chronic lymphocytic leukemia/lymphoma (BCL)-2 proteins compromise mitochondrial integrity through the process of mitochondrial outer membrane permeabilization (MOMP). For nearly three decades, intensive efforts focused on the identification and interactions of two key proapoptotic BCL-2 proteins: BCL-2 antagonist killer (BAK) and BCL-2-associated X (BAX). Indeed, we now have critical insights into which BCL-2 proteins interact with BAK/BAX to either preserve survival or initiate MOMP. In contrast, while mitochondria are targeted by BAK/BAX, a molecular understanding of how these organelles govern BAK/BAX function remains less clear. Here, we integrate recent mechanistic insights of proapoptotic BCL-2 protein function in the context of mitochondrial environment, and discuss current and potential pharmacological opportunities to control MOMP in disease.
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Affiliation(s)
- Mark P A Luna-Vargas
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Jerry Edward Chipuk
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA; The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA; The Diabetes, Obesity, and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA; Department of Dermatology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA; The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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Mignard V, Lalier L, Paris F, Vallette FM. Bioactive lipids and the control of Bax pro-apoptotic activity. Cell Death Dis 2014; 5:e1266. [PMID: 24874738 PMCID: PMC4047880 DOI: 10.1038/cddis.2014.226] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 12/19/2022]
Abstract
Lipids are key regulators of cell physiology through the control of many aspects of cellular life and survival. In particular, lipids have been implicated at different levels and through many different mechanisms in the cell death program called apoptosis. Here, we discuss the action of lipids in the regulation of the activation and the integration of Bax into the mitochondrial outer membrane, a key pro-apoptotic member of the BCL-2 family. We describe how, during apoptosis, lipids can act simultaneously or in parallel as receptors or ligands for Bax to stimulate or inhibit its pro-death activity.
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Affiliation(s)
- V Mignard
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
| | - L Lalier
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
| | - F Paris
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
| | - F M Vallette
- Centre de Recherche en Cancérologie Nantes Angers, Nantes, France
- Université de Nantes, Nantes, France
- Institut de Cancérologie de l'Ouest, Nantes, France
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Xu XP, Zhai D, Kim E, Swift M, Reed JC, Volkmann N, Hanein D. Three-dimensional structure of Bax-mediated pores in membrane bilayers. Cell Death Dis 2013; 4:e683. [PMID: 23788040 PMCID: PMC3702287 DOI: 10.1038/cddis.2013.210] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) is a member of the Bcl-2 protein family having a pivotal role in triggering cell commitment to apoptosis. Bax is latent and monomeric in the cytosol but transforms into its lethal, mitochondria-embedded oligomeric form in response to cell stress, leading to the release of apoptogenic factors such as cytochrome C. Here, we dissected the structural correlates of Bax membrane insertion while oligomerization is halted. This strategy was enabled through the use of nanometer-scale phospholipid bilayer islands (nanodiscs) the size of which restricts the reconstituted system to single Bax-molecule activity. Using this minimal reconstituted system, we captured structural correlates that precede Bax homo-oligomerization elucidating previously inaccessible steps of the core molecular mechanism by which Bcl-2 family proteins regulate membrane permeabilization. We observe that, in the presence of BH3 interacting domain death agonist (Bid) BH3 peptide, Bax monomers induce the formation of ~3.5-nm diameter pores and significantly distort the phospholipid bilayer. These pores are compatible with promoting release of ions as well as proteinaceous components, suggesting that membrane-integrated Bax monomers in the presence of Bid BH3 peptides are key functional units for the activation of the cell demolition machinery.
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Affiliation(s)
- X-P Xu
- Bioinformatics and Systems Biology Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
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Zhukovsky MA, Lee PH, Ott A, Helms V. Putative cholesterol-binding sites in human immunodeficiency virus (HIV) coreceptors CXCR4 and CCR5. Proteins 2012; 81:555-67. [DOI: 10.1002/prot.24211] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/31/2012] [Accepted: 10/11/2012] [Indexed: 11/08/2022]
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D'Souza K, Epand RM. Catalytic activity and acyl-chain selectivity of diacylglycerol kinase ɛ are modulated by residues in and near the lipoxygenase-like motif. J Mol Biol 2012; 416:619-28. [PMID: 22266092 DOI: 10.1016/j.jmb.2012.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 11/17/2022]
Abstract
Diacylglycerol kinase (DGK) ɛ plays an important role in the resynthesis of phosphatidylinositol by mediating the phosphorylation of diacylglycerol to phosphatidic acid. DGKɛ is unique among mammalian DGK isoforms in that it is the only one that shows acyl-chain selectivity, preferring diacylglycerols with an sn-2 arachidonoyl group. The region responsible for this arachidonoyl specificity is the lipoxygenase (LOX)-like motif found in the accessory domain, adjacent to DGKɛ's catalytic site. Many mutations within the LOX-like motif result in a loss of enzyme activity. However, the few mutants that retain significant activity exhibit some decrease in selectivity for the arachidonoyl chain. In the present work, we have explored mutations in a region adjacent to the LOX-like motif, which is also contained within the same hydrophobic segment of the protein. This adjacent region also contains a cholesterol recognition/interaction amino acid consensus motif. Being outside of the LOX-like motif, this region likely has less direct contact with the substrate, and more activity is retained with mutations. This has allowed us to probe in more detail the relationship between this region of the protein and substrate specificity. We demonstrate that this cholesterol recognition/interaction amino acid consensus domain also plays a role in acyl-chain selectivity. Despite the high degree of conservation of the amino acid sequence in this region of the protein, certain mutations result in proteins with higher activity than the wild-type protein. These mutations also result in a selective gain of acyl-chain preferences for diacylglycerols with different acyl-chain profiles. In addition to the LOX-like motif, adjacent residues also contribute to selectivity for diacylglycerols with specific acyl-chain compositions, such as those found in the phosphatidylinositol cycle.
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Affiliation(s)
- Kenneth D'Souza
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada
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