15 results on '"Alessandra Zarantonello"'
Search Results
2. Heme Interferes With Complement Factor I-Dependent Regulation by Enhancing Alternative Pathway Activation
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Alexandra Gerogianni, Jordan D. Dimitrov, Alessandra Zarantonello, Victoria Poillerat, Satheesh Chonat, Kerstin Sandholm, Karin E. McAdam, Kristina N. Ekdahl, Tom E. Mollnes, Camilla Mohlin, Lubka T. Roumenina, and Per H. Nilsson
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heme ,complement ,factor I ,co-factor activity ,hemopexin ,hemolysis ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Hemolysis, as a result of disease or exposure to biomaterials, is characterized by excess amounts of cell-free heme intravascularly and consumption of the protective heme-scavenger proteins in plasma. The liberation of heme has been linked to the activation of inflammatory systems, including the complement system, through alternative pathway activation. Here, we investigated the impact of heme on the regulatory function of the complement system. Heme dose-dependently inhibited factor I-mediated degradation of soluble and surface-bound C3b, when incubated in plasma or buffer with complement regulatory proteins. Inhibition occurred with factor H and soluble complement receptor 1 as co-factors, and the mechanism was linked to the direct heme-interaction with factor I. The heme-scavenger protein hemopexin was the main contaminant in purified factor I preparations. This led us to identify that hemopexin formed a complex with factor I in normal human plasma. These complexes were significantly reduced during acute vasoocclusive pain crisis in patients with sickle cell disease, but the complexes were normalized at their baseline outpatient clinic visit. Hemopexin exposed a protective function of factor I activity in vitro, but only when it was present before the addition of heme. In conclusion, we present a mechanistic explanation of how heme promotes uncontrolled complement alternative pathway amplification by interfering with the regulatory capacity of factor I. Reduced levels of hemopexin and hemopexin-factor I complexes during an acute hemolytic crisis is a risk factor for heme-mediated factor I inhibition.
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- 2022
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3. Functional and Structural Characterization of a Potent C1q Inhibitor Targeting the Classical Pathway of the Complement System
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Nick S. Laursen, Dennis V. Pedersen, Heidi Gytz, Alessandra Zarantonello, Jens Magnus Bernth Jensen, Annette G. Hansen, Steffen Thiel, and Gregers R. Andersen
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complement system ,nanobody ,antibody ,inhibitor ,C1q ,crystal structure ,Immunologic diseases. Allergy ,RC581-607 - Abstract
The classical pathway of complement is important for protection against pathogens and in maintaining tissue homeostasis, but excessive or aberrant activation is directly linked to numerous pathologies. We describe the development and in vitro characterization of C1qNb75, a single domain antibody (nanobody) specific for C1q, the pattern recognition molecule of the classical pathway. C1qNb75 binds to the globular head modules of human C1q with sub-nanomolar affinity and impedes classical pathway mediated hemolysis by IgG and IgM. Crystal structure analysis revealed that C1qNb75 recognizes an epitope primarily located in the C1q B-chain that overlaps with the binding sites of IgG and IgM. Thus, C1qNb75 competitively prevents C1q from binding to IgG and IgM causing blockade of complement activation by the classical pathway. Overall, C1qNb75 represents a high-affinity nanobody-based inhibitor of IgG- and IgM-mediated activation of the classical pathway and may serve as a valuable reagent in mechanistic and functional studies of complement, and as an efficient inhibitor of complement under conditions of excessive CP activation.
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- 2020
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4. Nanobodies Provide Insight into the Molecular Mechanisms of the Complement Cascade and Offer New Therapeutic Strategies
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Alessandra Zarantonello, Henrik Pedersen, Nick S. Laursen, and Gregers R. Andersen
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complement system ,proteolytic cascade ,convertase ,inhibitor ,structural biology ,molecular mechanism ,Microbiology ,QR1-502 - Abstract
The complement system is part of the innate immune response, where it provides immediate protection from infectious agents and plays a fundamental role in homeostasis. Complement dysregulation occurs in several diseases, where the tightly regulated proteolytic cascade turns offensive. Prominent examples are atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria and Alzheimer’s disease. Therapeutic intervention targeting complement activation may allow treatment of such debilitating diseases. In this review, we describe a panel of complement targeting nanobodies that allow modulation at different steps of the proteolytic cascade, from the activation of the C1 complex in the classical pathway to formation of the C5 convertase in the terminal pathway. Thorough structural and functional characterization has provided a deep mechanistic understanding of the mode of inhibition for each of the nanobodies. These complement specific nanobodies are novel powerful probes for basic research and offer new opportunities for in vivo complement modulation.
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- 2021
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5. Evolutionary trajectory of receptor binding specificity and promiscuity of the spike protein of SARS-CoV-2
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Cyril Planchais, Alejandra Reyes‐Ruiz, Robin Lacombe, Alessandra Zarantonello, Maxime Lecerf, Margot Revel, Lubka T. Roumenina, Boris P. Atanasov, Hugo Mouquet, Jordan D. Dimitrov, Immunologie humorale - Humoral Immunology, Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Centre de Recherche des Cordeliers (CRC (UMR_S_1138 / U1138)), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris Cité (UPCité), Bulgaria Academy of Sciences = Académie des Sciences de Bulgarie (BAS), This work was supported by Institut National de la Santé et de la Recherche Médicale (INSERM, France). Jordan D. Dimitrov is recipient of a grant from the European Research Council (Project CoBABATI ERC-StG-678905). Alejandra Reyes-Ruiz is recipient of fellowship from an Innovative Training Network (ITN) funded by the European Union's Horizon 2020 Programme under grant agreement No. 859974, project EDUC8. Alessandra Zarantonello is supported by the Danish Council for Independent Research (DFF-1025-00015B)., European Project: 678905,H2020-EU.1.1., ERC-StG-2015,CoBABATI(2016), European Project: 859974,H2020-EU.1.3. - EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions,EDUC8(2020), École pratique des hautes études (EPHE), Jordan, Dimitrov, Cofactor Binding Antibodies – Basic Aspects and Therapeutic Innovations - CoBABATI - - H2020-EU.1.1., ERC-StG-20152016-09-01 - 2021-08-31 - 678905 - VALID, and Early Stage Researchers EDUCational Program on Factor VIII Immunogenicity - EDUC8 - - H2020-EU.1.3. - EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions2020-04-01 - 2024-09-30 - 859974 - VALID
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[SDV.MP.VIR] Life Sciences [q-bio]/Microbiology and Parasitology/Virology ,[SDV.MHEP.ME] Life Sciences [q-bio]/Human health and pathology/Emerging diseases ,virus evolution ,[SDV.MHEP.ME]Life Sciences [q-bio]/Human health and pathology/Emerging diseases ,SARS-CoV-2 ,protein-protein interactions ,COVID-19 ,Peptidyl-Dipeptidase A ,binding promiscuity ,Biochemistry ,thermodynamics ,[SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases ,Spike Glycoprotein, Coronavirus ,[SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology ,[SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology ,[SDV.MHEP.MI] Life Sciences [q-bio]/Human health and pathology/Infectious diseases ,Humans ,protein electrostatics ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Angiotensin-Converting Enzyme 2 ,Molecular Biology ,Protein Binding - Abstract
SARS-CoV-2 infects cells by attachment to its receptor – the angiotensin converting enzyme 2 (ACE2). Regardless of the wealth of structural data, little is known about the physicochemical mechanism of interactions of the viral spike (S) protein with ACE2 and how this mechanism has evolved during the pandemic. Here, we applied experimental and computational approaches to characterize the molecular interaction of S proteins from SARS-CoV-2 variants of concern (VOC). Data on kinetics, activation- and equilibrium thermodynamics of binding of the receptor binding domain (RBD) from VOC with ACE2 as well as data from computational protein electrostatics revealed a profound remodeling of the physicochemical characteristics of the interaction during the evolution. Thus, as compared to RBDs from Wuhan strain and other VOC, Omicron RBD presented as a unique protein in terms of conformational dynamics and types of non-covalent forces driving the complex formation with ACE2. Viral evolution resulted in a restriction of the RBD structural dynamics, and a shift to a major role of polar forces for ACE2 binding. Further, we investigated how the reshaping of the physicochemical characteristics of interaction affect the binding specificity of S proteins. Data from various binding assays revealed that SARS-CoV-2 Wuhan and Omicron RBDs manifest capacity for promiscuous recognition of unrelated human proteins, but they harbor distinct reactivity patterns. These findings might contribute for mechanistic understanding of the viral tropism, and capacity to evade immune responses during evolution.
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- 2022
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6. An Ultrahigh-Affinity Complement C4b-Specific Nanobody Inhibits In Vivo Assembly of the Classical Pathway Proconvertase
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Jessy Presumey, Matthew B. Johnson, Steffen Thiel, Beth Stevens, Heidi Gytz Olesen, Esra Yalcin, Annette G. Hansen, Alessandra Zarantonello, Lea Simoni, Gregers R. Andersen, Nick S. Laursen, Michael C. Carroll, and Rachel Fox
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Induced Pluripotent Stem Cells ,Immunology ,Antibody Affinity ,chemical and pharmacologic phenomena ,Antigen-Antibody Complex ,Complement C3-C5 Convertases ,Mice ,Classical complement pathway ,Complement C4b ,Animals ,Humans ,Immunology and Allergy ,Complement Activation ,Cells, Cultured ,Mice, Knockout ,Neurons ,Chemistry ,Cell Differentiation ,Complement C3 ,Single-Domain Antibodies ,Acquired immune system ,C3-convertase ,Immune complex ,Up-Regulation ,Cell biology ,Complement system ,Complement C3-C5 Convertases, Classical Pathway ,Schizophrenia ,Alternative complement pathway ,Protein Multimerization - Abstract
The classical and lectin pathways of the complement system are important for the elimination of pathogens and apoptotic cells and stimulation of the adaptive immune system. Upon activation of these pathways, complement component C4 is proteolytically cleaved, and the major product C4b is deposited on the activator, enabling assembly of a C3 convertase and downstream alternative pathway amplification. Although excessive activation of the lectin and classical pathways contributes to multiple autoimmune and inflammatory diseases and overexpression of a C4 isoform has recently been linked to schizophrenia, a C4 inhibitor and structural characterization of the convertase formed by C4b is lacking. In this study, we present the nanobody hC4Nb8 that binds with picomolar affinity to human C4b and potently inhibits in vitro complement C3 deposition through the classical and lectin pathways in human serum and in mouse serum. The crystal structure of the C4b:hC4Nb8 complex and a three-dimensional reconstruction of the C4bC2 proconvertase obtained by electron microscopy together rationalize how hC4Nb8 prevents proconvertase assembly through recognition of a neoepitope exposed in C4b and reveals a unique C2 conformation compared with the alternative pathway proconvertase. On human induced pluripotent stem cell–derived neurons, the nanobody prevents C3 deposition through the classical pathway. Furthermore, hC4Nb8 inhibits the classical pathway-mediated immune complex delivery to follicular dendritic cells in vivo. The hC4Nb8 represents a novel ultrahigh-affinity inhibitor of the classical and lectin pathways of the complement cascade under both in vitro and in vivo conditions.
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- 2020
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7. C3-dependent effector functions of complement
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Alessandra Zarantonello, Margot Revel, Anne Grunenwald, Lubka T. Roumenina, Centre de Recherche des Cordeliers (CRC (UMR_S_1138 / U1138)), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris Cité (UPCité), and Roumenina, Lubka
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opsonin ,[SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM] ,[SDV.BBM.BS] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM] ,Immunology ,autoimmunity ,[SDV.CAN]Life Sciences [q-bio]/Cancer ,complement C3 ,anaphylatoxin ,[SDV.IMM.II]Life Sciences [q-bio]/Immunology/Innate immunity ,[SDV.CAN] Life Sciences [q-bio]/Cancer ,inflammation ,Immunology and Allergy ,cancer ,[SDV.IMM.II] Life Sciences [q-bio]/Immunology/Innate immunity - Abstract
International audience; C3 is the central effector molecule of the complement system, mediating its multiple functions through different binding sites and their corresponding receptors. We will introduce the C3 forms (native C3, C3 [H2 O], and intracellular C3), the C3 fragments C3a, C3b, iC3b, and C3dg/C3d, and the C3 expression sites. To highlight the important role that C3 plays in human biological processes, we will give an overview of the diseases linked to C3 deficiency and to uncontrolled C3 activation. Next, we will present a structural description of C3 activation and of the C3 fragments generated by complement regulation. We will proceed by describing the C3a interaction with the anaphylatoxin receptor, followed by the interactions of opsonins (C3b, iC3b, and C3dg/C3d) with complement receptors, divided into two groups: receptors bearing complement regulatory functions and the effector receptors without complement regulatory activity. We outline the molecular architecture of the receptors, their binding sites on the C3 activation fragments, the cells expressing them, the diversity of their functions, and recent advances. With this review, we aim to give an up-to-date analysis of the processes triggered by C3 activation fragments on different cell types in health and disease contexts.
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- 2022
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8. Purification of Human Complement Component C4 and Sample Preparation for Structural Biology Applications
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Alessandra, Zarantonello, Sofia, Mortensen, Nick S, Laursen, and Gregers R, Andersen
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Ion Exchange ,Proteomics ,Microscopy, Electron ,X-Ray Diffraction ,Protein Conformation ,Scattering, Small Angle ,Chromatography, Gel ,Humans ,Complement C4 ,Crystallography, X-Ray ,Biology ,Negative Staining - Abstract
Activated complement component C4 (C4b) is the nonenzymatic component of the classical pathway (CP) convertases of the complement system. Preparation of C4 and C4b samples suitable for structural biology studies is challenging due to low yields and complexity of recombinant C4 production protocols reported so far and heterogeneity of C4 in native sources. Here we present a purification protocol for human C4 and describe sample preparation methods for structural investigation of C4 and its complexes by crystallography, small angle X-ray scattering, and electron microscopy.
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- 2021
9. Nanobodies Provide Insight into the Molecular Mechanisms of the Complement Cascade and Offer New Therapeutic Strategies
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Gregers R. Andersen, Henrik Pedersen, Nick S. Laursen, and Alessandra Zarantonello
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0301 basic medicine ,Hemoglobinuria, Paroxysmal ,Molecular Conformation ,lcsh:QR1-502 ,Complement C3-C5 Convertases ,Review ,Biochemistry ,lcsh:Microbiology ,Epitopes ,0302 clinical medicine ,proteolytic cascade ,Complement C1 ,structural biology ,Complement Activation ,Convertase ,Atypical Hemolytic Uremic Syndrome ,Complement (complexity) ,inhibitor ,Nanomedicine ,030220 oncology & carcinogenesis ,molecular mechanism ,Structural biology ,Protein Binding ,Complement system ,Inhibitor ,Proteolytic cascade ,Biology ,Antibodies, Monoclonal, Humanized ,Molecular mechanism ,C5-convertase ,03 medical and health sciences ,Classical complement pathway ,Atypical hemolytic uremic syndrome ,medicine ,biochemistry ,Animals ,Humans ,Molecular Biology ,complement system ,Inflammation ,Innate immune system ,Complement System Proteins ,Single-Domain Antibodies ,medicine.disease ,convertase ,Immunity, Innate ,030104 developmental biology ,Immunoglobulin G ,Proteolysis ,Paroxysmal nocturnal hemoglobinuria ,Neuroscience - Abstract
The complement system is part of the innate immune response, where it provides immediate protection from infectious agents and plays a fundamental role in homeostasis. Complement dysregulation occurs in several diseases, where the tightly regulated proteolytic cascade turns offensive. Prominent examples are atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria and Alzheimer’s disease. Therapeutic intervention targeting complement activation may allow treatment of such debilitating diseases. In this review, we describe a panel of complement targeting nanobodies that allow modulation at different steps of the proteolytic cascade, from the activation of the C1 complex in the classical pathway to formation of the C5 convertase in the terminal pathway. Thorough structural and functional characterization has provided a deep mechanistic understanding of the mode of inhibition for each of the nanobodies. These complement specific nanobodies are novel powerful probes for basic research and offer new opportunities for in vivo complement modulation.
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- 2021
- Full Text
- View/download PDF
10. Structural Investigations of Human A2M Identify a Hollow Native Conformation That Underlies Its Distinctive Protease-Trapping Mechanism
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Jan Skov Pedersen, Alessandra Zarantonello, Jeppe Lyngsø, Peter Kresten Nielsen, Seandean Lykke Harwood, Gregers R. Andersen, Katarzyna Kjøge, and Jan J. Enghild
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PMSF, phenylmethanesulfonyl fluoride ,Conformational change ,Protein Conformation ,Dimer ,IFT, indirect Fourier transform ,A2M-MA, A2M treated with methylamine ,PROTEINASE BINDING ,COMPONENT C4 ,Biochemistry ,Mass Spectrometry ,COMPLEMENT ,Analytical Chemistry ,αM, alpha-macroglobulin superfamily ,chemistry.chemical_compound ,Protein structure ,Native state ,HUMAN ALPHA(2)-MACROGLOBULIN ,A2M-T, A2M which has been cleaved by trypsin ,LNK, linker region ,alpha 2 macroglobulin ,0303 health sciences ,CRYSTAL ,TE, thiol ester domain ,Chemistry ,030302 biochemistry & molecular biology ,SAXS, small-angle X-ray scattering ,SMALL-ANGLE SCATTERING ,Recombinant Proteins ,MA, methylamine ,A2MLNK/LNK, recombinant A2M with the Thr654Cys and Thr661Cys mutations ,CUB, the complement subcomponent C1r/C1s, urchin embryonic growth factor and bone morphogenetic protein 1 domain ,HUMAN ALPHA-2-MACROGLOBULIN ,medicine.drug ,HBS, HEPES-buffered saline, here defined as 20 mm HEPES-NaOH, 150 mM NaCl, pH 7.4 ,SEC, size-exclusion chromatography ,ECAM, E. coli α2-macroglobulin ,DSSO, disuccinimidyl sulfoxide ,FAST FORMS ,Cleavage (embryo) ,protease inhibitor ,03 medical and health sciences ,XL-MS, cross-linking-mass spectrometry ,conformational change ,Tetramer ,protein cross-linking ,Scattering, Small Angle ,medicine ,Humans ,A2M3K, recombinant A2M with the Arg704Lys, Arg715Lys, and Arg719Lys mutations ,alpha-Macroglobulins ,A2M, α2-macroglobulin (human, if not otherwise specified) ,BAIT REGION ,Molecular Biology ,030304 developmental biology ,structural model ,EM, electron microscopy ,electron microscopy ,Research ,LRP1, low-density lipoprotein receptor-related protein 1 ,MG, macroglobulin domain ,X-RAY-SCATTERING ,Protease inhibitor (biology) ,Microscopy, Electron ,HEK293 Cells ,RB, receptor-binding domain ,corresponds to MG8 in complement factors ,Mutation ,small-angle X-ray scattering ,Biophysics ,α1-i3, alpha-1 inhibitor 3, a monomeric rat protease inhibitor ,Linker ,macroglobulins ,Peptide Hydrolases - Abstract
Human α2-macroglobulin (A2M) is the most characterized protease inhibitor in the alpha-macroglobulin (αM) superfamily, but the structure of its native conformation has not been determined. Here, we combined negative stain electron microscopy (EM), small-angle X-ray scattering (SAXS), and cross-linking–mass spectrometry (XL-MS) to investigate native A2M and its collapsed conformations that are obtained through aminolysis of its thiol ester by methylamine or cleavage of its bait region by trypsin. The combined interpretation of these data resulted in a model of the native A2M tetramer and its conformational changes. Native A2M consists of two crescent-shaped disulfide-bridged subunit dimers, which face toward each other and surround a central hollow space. In native A2M, interactions across the disulfide-bridged dimers are minimal, with a single major interface between the linker (LNK) regions of oppositely positioned subunits. Bait region cleavage induces both intrasubunit domain repositioning and an altered configuration of the disulfide-bridged dimer. These changes collapse the tetramer into a more compact conformation, which encloses an interior protease-trapping cavity. A recombinant A2M with a modified bait region was used to map the bait region’s position in native A2M by XL-MS. A second recombinant A2M introduced an intersubunit disulfide into the LNK region, demonstrating the predicted interactions between these regions in native A2M. Altogether, our native A2M model provides a structural foundation for understanding A2M’s protease-trapping mechanism, its conformation-dependent receptor interactions, and the dissociation of native A2M into dimers due to inflammatory oxidative stress., Graphical Abstract, Highlights • Native A2M is hollow and tube-like. • A2M’s bait regions are oriented inward and are accessed from inside A2M. • A2M tetramerizes through symmetrical interactions between its LNK regions. • The receptor-binding site is in an inaccessible position inside native A2M., In Brief The native conformation of the protease inhibitor A2M was investigated using negative stain electron microscopy, small-angle X-ray scattering, and cross-linking mass spectrometry. The low-resolution model built from these data describes a hollow tubular configuration that explains several aspects of A2M’s unique trapping mechanism. This model was further validated by two recombinantly expressed A2M mutants, which probed the location of the bait region and demonstrated the existence of a critical interface between A2M’s disulfide-bridged dimers.
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- 2021
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11. Purification of Human Complement Component C4 and Sample Preparation for Structural Biology Applications
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Gregers R. Andersen, Nick S. Laursen, Alessandra Zarantonello, and Sofia Mortensen
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0301 basic medicine ,Gel filtration ,Small-angle X-ray scattering ,Chemistry ,Complement C4 ,Small angle X-ray scattering ,Combinatorial chemistry ,Complement system ,Complement (complexity) ,03 medical and health sciences ,Classical complement pathway ,030104 developmental biology ,0302 clinical medicine ,Structural biology ,Component (UML) ,Sample preparation ,Ion exchange ,030215 immunology ,Negative stain electron microscopy ,X-ray crystallography - Abstract
Activated complement component C4 (C4b) is the nonenzymatic component of the classical pathway (CP) convertases of the complement system. Preparation of C4 and C4b samples suitable for structural biology studies is challenging due to low yields and complexity of recombinant C4 production protocols reported so far and heterogeneity of C4 in native sources. Here we present a purification protocol for human C4 and describe sample preparation methods for structural investigation of C4 and its complexes by crystallography, small angle X-ray scattering, and electron microscopy.
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- 2021
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12. A Complement C3-Specific Nanobody for Modulation of the Alternative Cascade Identifies the C-Terminal Domain of C3b as Functional in C5 Convertase Activity
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Steffen Thiel, Dorte Christiansen, Beth Stevens, Gregers R. Andersen, Tom Eirik Mollnes, Neal Lojek, Nick S. Laursen, Pernille Libach Hansen, Annette G. Hansen, Trine A.F. Gadeberg, Rasmus K. Jensen, Sofia Mm Mazarakis, Matthew B. Johnson, Alessandra Zarantonello, Dennis Pedersen, Henrik Pedersen, Heidi Gytz Olesen, Rachel Fox, and Jens Magnus Bernth Jensen
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Innate immune system ,medicine.diagnostic_test ,Chemistry ,C-terminus ,Immunology ,Complement Pathway, Alternative ,Inflammation ,Single-Domain Antibodies ,Cleavage (embryo) ,C5-convertase ,Cell biology ,Flow cytometry ,Complement system ,Mice ,HEK293 Cells ,Complement C5 Convertase, Alternative Pathway ,Protein Domains ,Complement C3b ,medicine ,Alternative complement pathway ,Immunology and Allergy ,Animals ,Humans ,medicine.symptom - Abstract
The complement system is an intricate cascade of the innate immune system and plays a key role in microbial defense, inflammation, organ development, and tissue regeneration. There is increasing interest in developing complement regulatory and inhibitory agents to treat complement dysfunction. In this study, we describe the nanobody hC3Nb3, which is specific for the C-terminal C345c domain of human and mouse complement component C3/C3b/C3c and potently inhibits C3 cleavage by the alternative pathway. A high-resolution structure of the hC3Nb3–C345c complex explains how the nanobody blocks proconvertase assembly. Surprisingly, although the nanobody does not affect classical pathway–mediated C3 cleavage, hC3Nb3 inhibits classical pathway–driven hemolysis, suggesting that the C-terminal domain of C3b has an important function in classical pathway C5 convertase activity. The hC3Nb3 nanobody binds C3 with low nanomolar affinity in an SDS-resistant complex, and the nanobody is demonstrated to be a powerful reagent for C3 detection in immunohistochemistry and flow cytometry. Overall, the hC3Nb3 nanobody represents a potent inhibitor of both the alternative pathway and the terminal pathway, with possible applications in complement research, diagnostics, and therapeutics.
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- 2020
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13. Strong 1D localization and highly anisotropic electron-hole masses in heavy-halogen functionalized graphenes
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Beate Paulus, Lukas Eugen Marsoner Steinkasserer, and Alessandra Zarantonello
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Materials science ,General Physics and Astronomy ,FOS: Physical sciences ,02 engineering and technology ,Electron hole ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Adsorption ,Photovoltaics ,law ,0103 physical sciences ,Graphane ,Physical and Theoretical Chemistry ,010306 general physics ,Electronic band structure ,Fluorographene ,Condensed Matter - Materials Science ,business.industry ,Graphene ,Materials Science (cond-mat.mtrl-sci) ,021001 nanoscience & nanotechnology ,chemistry ,Chemical physics ,Charge carrier ,0210 nano-technology ,business - Abstract
While halogenation of graphene presents a fascinating avenue to the construction of a chemically and physically diverse class of systems, their application in photovoltaics has been hindered by often prohibitively large optical gaps. Herein we study the effects of partial bromination and chlorination on the structure and optoelectronic properties of both graphane and fluorographene. We find brominated and chlorinated fluorographene derivatives to be as stable as graphane making them likely to be durable even at elevated temperatures. A detailed investigation of the systems band structure reveals significant 1D localization of the charge carriers as well as strongly electron-hole asymmetric effective masses. Lastly using $G_0W_0$ and BSE, we investigate the optical adsorption spectra of the aforementioned materials whose first adsorption peak is shown to lie close to the optimal peak position for photovoltaic applications ($\approx 1.5$ eV).
- Published
- 2016
14. Activation of C1, the complex initiating the classical pathway of the complement cascade, through cross-complex activation of proteases
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Simon A. Mortensen, Steffen Thiel, Annette G. Hansen, Gregers R. Andersen, and Alessandra Zarantonello
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Classical complement pathway ,Proteases ,Complement component 2 ,Chemistry ,Lectin pathway ,Immunology ,Complement membrane attack complex ,Molecular Biology ,Cell biology ,Complement system - Published
- 2017
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15. Two potent C4 and C4b nanobodies inhibiting the classical pathway of the complement system
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Steffen Thiel, Gregers R. Andersen, Christine Schar, Nick S. Laursen, Trine Amalie Fogh Gadeberg, Dennis Pedersen, Alessandra Zarantonello, and Annette G. Hansen
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Classical complement pathway ,Chemistry ,Immunology ,Molecular Biology ,Complement system ,Cell biology - Published
- 2018
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