1
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Faull SV, Elliston ELK, Gooptu B, Jagger AM, Aldobiyan I, Redzej A, Badaoui M, Heyer-Chauhan N, Rashid ST, Reynolds GM, Adams DH, Miranda E, Orlova EV, Irving JA, Lomas DA. The structural basis for Z α 1-antitrypsin polymerization in the liver. SCIENCE ADVANCES 2020; 6:6/43/eabc1370. [PMID: 33087346 PMCID: PMC7577719 DOI: 10.1126/sciadv.abc1370] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 09/08/2020] [Indexed: 05/22/2023]
Abstract
The serpinopathies are among a diverse set of conformational diseases that involve the aberrant self-association of proteins into ordered aggregates. α1-Antitrypsin deficiency is the archetypal serpinopathy and results from the formation and deposition of mutant forms of α1-antitrypsin as "polymer" chains in liver tissue. No detailed structural analysis has been performed of this material. Moreover, there is little information on the relevance of well-studied artificially induced polymers to these disease-associated molecules. We have isolated polymers from the liver tissue of Z α1-antitrypsin homozygotes (E342K) who have undergone transplantation, labeled them using a Fab fragment, and performed single-particle analysis of negative-stain electron micrographs. The data show structural equivalence between heat-induced and ex vivo polymers and that the intersubunit linkage is best explained by a carboxyl-terminal domain swap between molecules of α1-antitrypsin.
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Affiliation(s)
- Sarah V Faull
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
| | - Emma L K Elliston
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
| | - Bibek Gooptu
- Leicester Institute of Structural and Chemical Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 7HB, UK
- National Institute for Health Research (NIHR) Leicester BRC-Respiratory, Leicester, UK
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, University of London, London WC1E 7HX, UK
| | - Alistair M Jagger
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
| | - Ibrahim Aldobiyan
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
| | - Adam Redzej
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, University of London, London WC1E 7HX, UK
| | - Magd Badaoui
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
| | - Nina Heyer-Chauhan
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
| | - S Tamir Rashid
- Centre for Stem Cells and Regenerative Medicine and Institute for Liver Studies, King's College London, London WC2R 2LS, UK
| | - Gary M Reynolds
- Centre for Liver Research and NIHR Birmingham Liver Biomedical Research Unit, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
| | - David H Adams
- Centre for Liver Research and NIHR Birmingham Liver Biomedical Research Unit, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
| | - Elena Miranda
- Department of Biology and Biotechnologies "Charles Darwin" and Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy
| | - Elena V Orlova
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, University of London, London WC1E 7HX, UK
| | - James A Irving
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
| | - David A Lomas
- UCL Respiratory, University College London, 5 University Street, London WC1E 6JF, UK.
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BN, UK
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2
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Abstract
Serine proteinase inhibitors (serpins), typically fold to a metastable native state and undergo a major conformational change in order to inhibit target proteases. However, conformational lability of the native serpin fold renders them susceptible to misfolding and aggregation, and underlies misfolding diseases such as α1-antitrypsin deficiency. Serpin specificity towards its protease target is dictated by its flexible and solvent exposed reactive centre loop (RCL), which forms the initial interaction with the target protease during inhibition. Previous studies have attempted to alter the specificity by mutating the RCL to that of a target serpin, but the rules governing specificity are not understood well enough yet to enable specificity to be engineered at will. In this paper, we use conserpin, a synthetic, thermostable serpin, as a model protein with which to investigate the determinants of serpin specificity by engineering its RCL. Replacing the RCL sequence with that from α1-antitrypsin fails to restore specificity against trypsin or human neutrophil elastase. Structural determination of the RCL-engineered conserpin and molecular dynamics simulations indicate that, although the RCL sequence may partially dictate specificity, local electrostatics and RCL dynamics may dictate the rate of insertion during protease inhibition, and thus whether it behaves as an inhibitor or a substrate. Engineering serpin specificity is therefore substantially more complex than solely manipulating the RCL sequence, and will require a more thorough understanding of how conformational dynamics achieves the delicate balance between stability, folding and function required by the exquisite serpin mechanism of action.
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3
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In Vitro Approaches for the Assessment of Serpin Polymerization. Methods Mol Biol 2018. [PMID: 30194595 DOI: 10.1007/978-1-4939-8645-3_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Serpin polymerization is the result of end-to-end ordered aggregation of serpin monomers into linear unbranched chains. This change in molecular state represents the basis of several conformational diseases with pathological gain-of-function and loss-of-function phenotypes, termed serpinopathies. Tools that enable quantification and characterization of polymer formation are therefore important to the study of serpin behavior in this pathophysiological context. Such methods rely on different manifestations of molecular change: polymerization-the generation of molecules with increasing molecular weight-is accompanied by concomitant structural rearrangements in the constituent subunits. Different approaches may be appropriate dependent on whether measurements are made on static samples, such as tissue or cell culture extracts, or in time-resolved experiments, often undertaken using polymers artificially induced under in vitro destabilizing conditions. In the former category, we describe the application of polyacrylamide electrophoresis, Western blot, ELISA, and negative-stain electron microscopy and in the latter category, Förster resonance energy transfer and fluorescence spectroscopy using environment-sensitive probes.
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4
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Nagahashi K, Takano K, Suzuki-Inoue K, Kanayama N, Umemura K, Urano T, Iwaki T. Mutation in a highly conserved glycine residue in strand 5B of plasminogen activator inhibitor 1 causes polymerisation. Thromb Haemost 2017; 117:860-869. [DOI: 10.1160/th16-07-0572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 01/27/2017] [Indexed: 11/05/2022]
Abstract
SummarySerpinopathy is characterised as abnormal accumulation of serine protease inhibitors (SERPINs) in cells and results in clinical symptoms owing to lack of SERPIN function or excessive accumulation of abnormal SERPIN. We recently identified a patient with functional deficiency of plasminogen activator inhibitor-1 (PAI-1), a member of the SERPIN superfamily. The patient exhibited life-threatening bleeding tendencies, which have also been observed in patients with a complete deficiency in PAI-1. Sequence analysis revealed a homozygous singlenucleotide substitution from guanine to cytosine at exon 9, which changed amino acid residue 397 from glycine to arginine (c.1189G>C; p.Gly397Arg). This glycine was located in strand 5B and was well conserved in other serpins. The mutant PAI-1 was polymerised in the cells, interfering with PAI-1 secretion. The corresponding mutations in SERPINC1 (anti-thrombin III) at position 456 (Gly456Arg) and SERPINI1 (neuroserpin) at position 392 (Gly392Glu) caused an anti-thrombin deficiency and severe dementia due to intracellular retention of the polymers. Glycine is the smallest amino acid, and these mutated amino acids were larger and charged. To determine which factors were important, further mutagenesis of PAI-1 was performed. Although the G397A, C, I, L, S, T, and V were secreted, the G397D, E, F, H, K, M, N, P, Q, W, and Y were not secreted. The results revealed that the size was likely triggered by the polymerisation of SEPRINs at this position. Structural analyses of this mutated PAI-1 would be useful to develop a novel PAI-1 inhibitor, which may be applicable in the context of several pathological states.
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5
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Pautus S, Alami M, Adam F, Bernadat G, Lawrence DA, De Carvalho A, Ferry G, Rupin A, Hamze A, Champy P, Bonneau N, Gloanec P, Peglion JL, Brion JD, Bianchini EP, Borgel D. Characterization of the Annonaceous acetogenin, annonacinone, a natural product inhibitor of plasminogen activator inhibitor-1. Sci Rep 2016; 6:36462. [PMID: 27876785 PMCID: PMC5120274 DOI: 10.1038/srep36462] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 10/17/2016] [Indexed: 12/26/2022] Open
Abstract
Plasminogen activator inhibitor-1 (PAI-1) is the main inhibitor of the tissue type and urokinase type plasminogen activators. High levels of PAI-1 are correlated with an increased risk of thrombotic events and several other pathologies. Despite several compounds with in vitro activity being developed, none of them are currently in clinical use. In this study, we evaluated a novel PAI-1 inhibitor, annonacinone, a natural product from the Annonaceous acetogenins group. Annonacinone was identified in a chromogenic screening assay and was more potent than tiplaxtinin. Annonacinone showed high potency ex vivo on thromboelastography and was able to potentiate the thrombolytic effect of tPA in vivo in a murine model. SDS-PAGE showed that annonacinone inhibited formation of PAI-1/tPA complex via enhancement of the substrate pathway. Mutagenesis and molecular dynamics allowed us to identify annonacinone binding site close to helix D and E and β-sheets 2A.
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Affiliation(s)
- Stéphane Pautus
- Université Paris-Sud, INSERM UMR-S1176, 94276 Le Kremlin-Bicêtre, France.,Servier Research Institute, 11 rue des Moulineaux 92150 Suresnes, France
| | - Mouad Alami
- Université Paris-Sud, BioCIS, 5 rue Jean-Baptiste Clément 92290 Châtenay-Malabry, France
| | - Fréderic Adam
- Université Paris-Sud, INSERM UMR-S1176, 94276 Le Kremlin-Bicêtre, France
| | - Guillaume Bernadat
- Université Paris-Sud, BioCIS, 5 rue Jean-Baptiste Clément 92290 Châtenay-Malabry, France
| | - Daniel A Lawrence
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Allan De Carvalho
- Université Paris-Sud, INSERM UMR-S1176, 94276 Le Kremlin-Bicêtre, France
| | - Gilles Ferry
- Servier Research Institute, 11 rue des Moulineaux 92150 Suresnes, France
| | - Alain Rupin
- Servier Research Institute, 11 rue des Moulineaux 92150 Suresnes, France
| | - Abdallah Hamze
- Université Paris-Sud, BioCIS, 5 rue Jean-Baptiste Clément 92290 Châtenay-Malabry, France
| | - Pierre Champy
- Laboratoire de Pharmacognosie, BioCIS, Univ. Paris-Sud, CNRS, Université Paris-Saclay, UFR Pharmacie, 5 rue Jean-Baptiste Clément, 92290, Châtenay-Malabry, France
| | - Natacha Bonneau
- Laboratoire de Pharmacognosie, BioCIS, Univ. Paris-Sud, CNRS, Université Paris-Saclay, UFR Pharmacie, 5 rue Jean-Baptiste Clément, 92290, Châtenay-Malabry, France
| | - Philippe Gloanec
- Servier Research Institute, 11 rue des Moulineaux 92150 Suresnes, France
| | - Jean-Louis Peglion
- Servier Research Institute, 11 rue des Moulineaux 92150 Suresnes, France
| | - Jean-Daniel Brion
- Université Paris-Sud, BioCIS, 5 rue Jean-Baptiste Clément 92290 Châtenay-Malabry, France
| | - Elsa P Bianchini
- Université Paris-Sud, INSERM UMR-S1176, 94276 Le Kremlin-Bicêtre, France
| | - Delphine Borgel
- Université Paris-Sud, INSERM UMR-S1176, 94276 Le Kremlin-Bicêtre, France.,AP-HP, Hôpital Necker, Service d'Hématologie Biologique, 75015 Paris, France
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6
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Caccia S, Ricagno S, Bolognesi M. Molecular bases of neuroserpin function and pathology. Biomol Concepts 2015; 1:117-30. [PMID: 25961991 DOI: 10.1515/bmc.2010.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Serpins build a large and evolutionary widespread protein superfamily, hosting members that are mainly Ser-protease inhibitors. Typically, serpins display a conserved core domain composed of three main β-sheets and 9-10 α-helices, for a total of approximately 350 amino acids. Neuroserpin (NS) is mostly expressed in neurons and in the central and peripheral nervous systems, where it targets tissue-type plasminogen activator. NS activity is relevant for axogenesis, synaptogenesis and synaptic plasticity. Five (single amino acid) NS mutations are associated with severe neurodegenerative disease in man, leading to early onset dementia, epilepsy and neuronal death. The functional aspects of NS protease inhibition are linked to the presence of a long exposed loop (reactive center loop, RCL) that acts as bait for the incoming partner protease. Large NS conformational changes, associated with the cleavage of the RCL, trap the protease in an acyl-enzyme complex. Contrary to other serpins, this complex has a half-life of approximately 10 min. Conformational flexibility is held to be at the bases of NS polymerization leading to Collins bodies intracellular deposition and neuronal damage in the pathological NS variants. Two main general mechanisms of serpin polymerization are currently discussed. Both models require the swapping of the RCL among neighboring serpin molecules. Specific differences in the size of swapped regions, as well as differences in the folding stage at which polymerization can occur, distinguish the two models. The results provided by recent crystallographic and biophysical studies allow rationalization of the functional and pathological roles played by NS based on the analysis of four three-dimensional structures.
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7
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Behrens MA, Sendall TJ, Pedersen JS, Kjeldgaard M, Huntington JA, Jensen JK. The shapes of Z-α1-antitrypsin polymers in solution support the C-terminal domain-swap mechanism of polymerization. Biophys J 2014; 107:1905-1912. [PMID: 25418171 PMCID: PMC4213723 DOI: 10.1016/j.bpj.2014.08.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 08/22/2014] [Accepted: 08/26/2014] [Indexed: 11/20/2022] Open
Abstract
Emphysema and liver cirrhosis can be caused by the Z mutation (Glu342Lys) in the serine protease inhibitor α1-antitrypsin (α1AT), which is found in more than 4% of the Northern European population. Homozygotes experience deficiency in the lung concomitantly with a massive accumulation of polymers within hepatocytes, causing their destruction. Recently, it was proposed that Z-α1AT polymerizes by a C-terminal domain swap. In this study, small-angle x-ray scattering (SAXS) was used to characterize Z-α1AT polymers in solution. The data show that the Z-α1AT trimer, tetramer, and pentamer all form ring-like structures in strong support of a common domain-swap polymerization mechanism that can lead to self-terminating polymers.
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Affiliation(s)
- Manja A Behrens
- Department of Chemistry, Aarhus University, Aarhus, Denmark; iNANO Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark; Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden
| | - Timothy J Sendall
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Jan S Pedersen
- Department of Chemistry, Aarhus University, Aarhus, Denmark; iNANO Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Morten Kjeldgaard
- Department of Molecular Biology, and Genetics, Aarhus University, Aarhus, Denmark
| | - James A Huntington
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Jan K Jensen
- Department of Molecular Biology, and Genetics, Aarhus University, Aarhus, Denmark; Danish-Chinese Centre for Proteases and Cancer, Aarhus University, Aarhus, Denmark.
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8
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Lin Z, Jensen JK, Hong Z, Shi X, Hu L, Andreasen PA, Huang M. Structural insight into inactivation of plasminogen activator inhibitor-1 by a small-molecule antagonist. ACTA ACUST UNITED AC 2013; 20:253-61. [PMID: 23438754 DOI: 10.1016/j.chembiol.2013.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 12/24/2012] [Accepted: 12/27/2012] [Indexed: 12/19/2022]
Abstract
Plasminogen activator inhibitor-1 (PAI-1), a serpin, is the physiological inhibitor of tissue-type and urokinase-type plasminogen activators and thus also an inhibitor of fibrinolysis and tissue remodeling. It is a potential therapeutic target in many pathological conditions, including thrombosis and cancer. Several types of PAI-1 antagonist have been developed, but the structural basis for their action has remained largely unknown. Here we report X-ray crystal structure analysis of PAI-1 in complex with a small-molecule antagonist, embelin. We propose a mechanism for embelin-induced rapid conversion of PAI-1 into a substrate for its target proteases and the subsequent slow conversion of PAI-1 into an irreversibly inactivated form. Our work provides structural clues to an understanding of PAI-1 inactivation by small-molecule antagonists and an important step toward the design of drugs targeting PAI-1.
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Affiliation(s)
- Zhonghui Lin
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
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9
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Toubarro D, Avila MM, Hao Y, Balasubramanian N, Jing Y, Montiel R, Faria TQ, Brito RM, Simões N. A serpin released by an entomopathogen impairs clot formation in insect defense system. PLoS One 2013; 8:e69161. [PMID: 23874900 PMCID: PMC3712955 DOI: 10.1371/journal.pone.0069161] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 06/07/2013] [Indexed: 11/18/2022] Open
Abstract
Steinernema carpocapsae is an entomopathogenic nematode widely used for the control of insect pests due to its virulence, which is mainly attributed to the ability the parasitic stage has to overcome insect defences. To identify the mechanisms underlying such a characteristic, we studied a novel serpin-like inhibitor (sc-srp-6) that was detected in a transcriptome analysis. Recombinant Sc-SRP-6 produced in Escherichia coli had a native fold of serpins belonging to the α-1-peptidase family and exhibited inhibitory activity against trypsin and α-chymotrypsin with Ki of 0.42×10−7 M and 1.22×10−7 M, respectively. Functional analysis revealed that Sc-SRP-6 inhibits insect digestive enzymes, thus preventing the hydrolysis of ingested particles. Moreover, Sc-SRP-6 impaired the formation of hard clots at the injury site, a major insect defence mechanism against invasive pathogens. Sc-SRP-6 does not prevent the formation of clot fibres and the activation of prophenoloxidases but impairs the incorporation of the melanin into the clot. Binding assays showed a complex formation between Sc-SRP-6 and three proteins in the hemolymph of lepidopteran required for clotting, apolipophorin, hexamerin and trypsin-like, although the catalytic inhibition occurred exclusively in trypsin-like. This data allowed the conclusion that Sc-SRP-6 promotes nematode virulence by inhibiting insect gut juices and by impairing immune clot reaction.
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Affiliation(s)
- Duarte Toubarro
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
| | - Mónica M. Avila
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
| | - YouJin Hao
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
| | - Natesan Balasubramanian
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
| | - Yingjun Jing
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
| | - Rafael Montiel
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Guanajuato, Mexico
| | - Tiago Q. Faria
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Rui M. Brito
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Nelson Simões
- Centro Investigação Recursos Naturais do Centro de Biotecnologia dos Açores, Associate Laboratory of Institute for Biotechnology and Bioengineering, Department of Biology, University of Azores, Ponta Delgada, Portugal
- * E-mail:
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10
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Minkevich NI, Rakitina TV, Bogachuk AP, Radchenko VV, Surina EA, Morozova-Roche LA, Yanamandra K, Iomdina EN, Babichenko II, Kostanian IA, Lipkin VM. [Amyloid-like fibrils forming and fibroblasts destruction in Tenon's capsule in progressive myopia as a result of pigment epithelium derived factor resistance to restricted proteolysis]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2013; 38:683-90. [PMID: 23547472 DOI: 10.1134/s1068162012060118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We have shown previously the presence of full length (50 kD) and truncated proteolytic form (45 kD) of pigment epithelium derived factor (PEDF) in the eye Tenon's capsule in progressive myopia. The full length PEDF is prevalent in myopia that correlates with breach in collagen fibrils forming. Immunohistochemical analysis of Tenon's capsule with polyclonal antibodies to PEDF revealed PEDF in control group being exclusively inside fibroblasts, whereas in myopia, PEDF was distributed extracellularly as halo around blasted fibroblasts. By means of atomic force microscopy and immunodot analysis with anti amyloid fibrils antibodies the ability was studied of recombinant PEDF fragments to form fibrils. Only full length PEDF was shown to form amyloid like fibril structures, but not the truncated form. Accumulation offibrils results in fibroblasts destruction and might be the cause of changes in biochemical and morphological structure of Tenon's capsule observed in myopia.
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11
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The roles of helix I and strand 5A in the folding, function and misfolding of α1-antitrypsin. PLoS One 2013; 8:e54766. [PMID: 23382962 PMCID: PMC3558512 DOI: 10.1371/journal.pone.0054766] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 12/14/2012] [Indexed: 11/19/2022] Open
Abstract
α1-Antitrypsin, the archetypal member of the serpin superfamily, is a metastable protein prone to polymerization when exposed to stressors such as elevated temperature, low denaturant concentrations or through the presence of deleterious mutations which, in a physiological context, are often associated with disease. Experimental evidence suggests that α1-Antitrypsin can polymerize via several alternative mechanisms in vitro. In these polymerization mechanisms different parts of the molecule are proposed to undergo conformational change. Both strand 5 and helix I are proposed to adopt different conformations when forming the various polymers, and possess a number of highly conserved residues however their role in the folding and misfolding of α1-Antitrypsin has never been examined. We have therefore created a range of α1Antitypsin variants in order to explore the role of these conserved residues in serpin folding, misfolding, stability and function. Our data suggest that key residues in helix I mediate efficient folding from the folding intermediate and residues in strand 5A ensure native state stability in order to prevent misfolding. Additionally, our data indicate that helix I is involved in the inhibitory process and that both structural elements undergo differing conformational rearrangements during unfolding and misfolding. These findings suggest that the ability of α1-Antitrypsin to adopt different types of polymers under different denaturing conditions may be due to subtle conformational differences in the transiently populated structures adopted prior to the I and M* states.
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12
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Blanchet X, Péré-Brissaud A, Duprat N, Pinault E, Delourme D, Ouali A, Combet C, Maftah A, Pélissier P, Brémaud L. Mutagenesis of the bovSERPINA3-3 demonstrates the requirement of aspartate-371 for intermolecular interaction and formation of dimers. Protein Sci 2012; 21:977-86. [PMID: 22505318 DOI: 10.1002/pro.2078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/30/2012] [Accepted: 04/02/2012] [Indexed: 11/10/2022]
Abstract
The family of serpins is known to fold into a metastable state that is required for the proteinase inhibition mechanism. One of the consequences of this conformational flexibility is the tendency of some mutated serpins to form polymers, which occur through the insertion of the reactive center loop of one serpin molecule into the A-sheet of another. This "A-sheet polymerization" has remained an attractive explanation for the molecular mechanism of serpinopathies. Polymerization of serpins can also take place in vitro under certain conditions (e.g., pH or temperature). Surprisingly, on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, bovSERPINA3-3 extracted from skeletal muscle or expressed in Escherichia coli was mainly observed as a homodimer. Here, in this report, by site-directed mutagenesis of recombinant bovSERPINA3-3, with substitution D371A, we demonstrate the importance of D371 for the intermolecular linkage observed in denaturing and reducing conditions. This residue influences the electrophoretic and conformational properties of bovSERPINA3-3. By structural modeling of mature bovSERPINA3-3, we propose a new "non-A-sheet swap" model of serpin homodimer in which D371 is involved at the molecular interface.
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Affiliation(s)
- X Blanchet
- Faculté des Sciences et Techniques, INRA, UMR1061 Unité de génétique Moléculaire Animale, Université de Limoges, FR 3503 GEIST, 87060 Limoges, France
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13
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Roussel BD, Irving JA, Ekeowa UI, Belorgey D, Haq I, Ordóñez A, Kruppa AJ, Duvoix A, Rashid ST, Crowther DC, Marciniak SJ, Lomas DA. Unravelling the twists and turns of the serpinopathies. FEBS J 2011; 278:3859-67. [DOI: 10.1111/j.1742-4658.2011.08201.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Lin Z, Jiang L, Yuan C, Jensen JK, Zhang X, Luo Z, Furie BC, Furie B, Andreasen PA, Huang M. Structural basis for recognition of urokinase-type plasminogen activator by plasminogen activator inhibitor-1. J Biol Chem 2011; 286:7027-32. [PMID: 21199867 PMCID: PMC3044959 DOI: 10.1074/jbc.m110.204537] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/15/2010] [Indexed: 11/06/2022] Open
Abstract
Plasminogen activator inhibitor-1 (PAI-1), together with its physiological target urokinase-type plasminogen activator (uPA), plays a pivotal role in fibrinolysis, cell migration, and tissue remodeling and is currently recognized as being among the most extensively validated biological prognostic factors in several cancer types. PAI-1 specifically and rapidly inhibits uPA and tissue-type PA (tPA). Despite extensive structural/functional studies on these two reactions, the underlying structural mechanism has remained unknown due to the technical difficulties of obtaining the relevant structures. Here, we report a strategy to generate a PAI-1·uPA(S195A) Michaelis complex and present its crystal structure at 2.3-Å resolution. In this structure, the PAI-1 reactive center loop serves as a bait to attract uPA onto the top of the PAI-1 molecule. The P4-P3' residues of the reactive center loop interact extensively with the uPA catalytic site, accounting for about two-thirds of the total contact area. Besides the active site, almost all uPA exosite loops, including the 37-, 60-, 97-, 147-, and 217-loops, are involved in the interaction with PAI-1. The uPA 37-loop makes an extensive interaction with PAI-1 β-sheet B, and the 147-loop directly contacts PAI-1 β-sheet C. Both loops are important for initial Michaelis complex formation. This study lays down a foundation for understanding the specificity of PAI-1 for uPA and tPA and provides a structural basis for further functional studies.
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Affiliation(s)
- Zhonghui Lin
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
| | - Longguang Jiang
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
| | - Cai Yuan
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
- the Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Jan K. Jensen
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
- the Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark, and
| | - Xu Zhang
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
| | - Zhipu Luo
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
| | - Barbara C. Furie
- the Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Bruce Furie
- the Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
| | - Peter A. Andreasen
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
- the Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark, and
| | - Mingdong Huang
- From the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences and
- the Danish-Chinese Centre for Proteases and Cancer, Fuzhou 350002, China
- the Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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15
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Abstract
A balance between proteolytic activity and protease inhibition is required to maintain the appropriate function of biological systems in which proteases play a role. The Myeloid and Erythroid Nuclear Termination protein, MENT, is a nonhistone heterochromatin-associated serpin that is an effective inhibitor of the papain-like cysteine proteases. Our laboratories have extensively investigated the dual functions of this protein, namely, chromatin condensation and protease inhibition. Unlike other serpins to date, MENT contains a unique insertion between the C- and D-helices known as the "M-loop." This loop contains two critical functional motifs that allow the nuclear function of MENT, namely, nuclear localization and DNA binding. However, the nuclear function of MENT is not restricted to the activities of the M-loop alone. In vitro, MENT brings about the dramatic remodeling of chromatin into higher-order structures by forming protein bridges via its reactive center loop. Further, we have determined that in a protease-mediated effect, DNA can act as a cofactor to accelerate the rate at which MENT can inhibit its target proteases. In this chapter, we discuss the isolation of MENT from native chicken blood as well as recombinant protein produced in Escherichia coli. Various techniques including in vitro functional assays and biophysical characterization are explained that can be used to elucidate the ability of the protein to interact with DNA and other deoxynucleoprotein complexes. In situ chromatin precipitation using natively purified MENT is also detailed.
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Affiliation(s)
- Sergei Grigoryev
- Department of Biochemistry & Molecular Biology, Penn State University College of Medicine, Milton S. Hershey Medical Center, University Drive, Hershey, Pennsylvania, USA
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16
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17
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Belorgey D, Hägglöf P, Onda M, Lomas DA. pH-dependent stability of neuroserpin is mediated by histidines 119 and 138; implications for the control of beta-sheet A and polymerization. Protein Sci 2010; 19:220-8. [PMID: 19953505 PMCID: PMC2865726 DOI: 10.1002/pro.299] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 09/24/2009] [Accepted: 11/16/2009] [Indexed: 11/09/2022]
Abstract
Neuroserpin is a member of the serpin superfamily. Point mutations in the neuroserpin gene underlie the autosomal dominant dementia, familial encephalopathy with neuroserpin inclusion bodies. This is characterized by the retention of ordered polymers of neuroserpin within the endoplasmic reticulum of neurons. pH has been shown to affect the propensity of several serpins to form polymers. In particular, low pH favors the formation of polymers of both alpha(1)-antitrypsin and antithrombin. We report here opposite effects in neuroserpin, with a striking resistance to polymer formation at acidic pH. Mutation of specific histidine residues showed that this effect is not attributable to the shutter domain histidine as would be predicted by analogy with other serpins. Indeed, mutation of the shutter domain His338 decreased neuroserpin stability but had no effect on the pH dependence of polymerization when compared with the wild-type protein. In contrast, mutation of His119 or His138 reduced the polymerization of neuroserpin at both acidic and neutral pH. These residues are at the lower pole of neuroserpin and provide a novel mechanism to control the opening of beta-sheet A and hence polymerization. This mechanism is likely to have evolved to protect neuroserpin from the acidic environment of the secretory granules.
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Affiliation(s)
- Didier Belorgey
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom.
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18
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Knaupp AS, Levina V, Robertson AL, Pearce MC, Bottomley SP. Kinetic Instability of the Serpin Z α1-Antitrypsin Promotes Aggregation. J Mol Biol 2010; 396:375-83. [PMID: 19944704 DOI: 10.1016/j.jmb.2009.11.048] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 11/28/2022]
Affiliation(s)
- Anja S Knaupp
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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19
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Gooptu B, Lomas DA. Conformational pathology of the serpins: themes, variations, and therapeutic strategies. Annu Rev Biochem 2009; 78:147-76. [PMID: 19245336 DOI: 10.1146/annurev.biochem.78.082107.133320] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Point mutations cause members of the serine protease inhibitor (serpin) superfamily to undergo a novel conformational transition, forming ordered polymers. These polymers characterize a group of diseases termed the serpinopathies. The formation of polymers underlies the retention of alpha(1)-antitrypsin within hepatocytes and of neuroserpin within neurons to cause cirrhosis and dementia, respectively. Point mutations of antithrombin, C1 inhibitor, alpha(1)-antichymotrypsin, and heparin cofactor II cause a similar conformational transition, resulting in a plasma deficiency that is associated with thrombosis, angioedema, and emphysema. Polymers of serpins can also form in extracellular tissues where they activate inflammatory cascades. This is best described for the Z variant of alpha(1)-antitrypsin in which the proinflammatory properties of polymers provide an explanation for both progressive emphysema and the selective advantage of this mutant allele. Therapeutic strategies are now being developed to block the aberrant conformational transitions and so treat the serpinopathies.
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Affiliation(s)
- Bibek Gooptu
- School of Crystallography, Birkbeck College, University of London, London, UK.
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20
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Ko CW, Wei Z, Marsh RJ, Armoogum DA, Nicolaou N, Bain AJ, Zhou A, Ying L. Probing nanosecond motions of plasminogen activator inhibitor-1 by time-resolved fluorescence anisotropy. MOLECULAR BIOSYSTEMS 2009; 5:1025-31. [DOI: 10.1039/b901691k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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21
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Zhang Q, Law RHP, Bottomley SP, Whisstock JC, Buckle AM. A structural basis for loop C-sheet polymerization in serpins. J Mol Biol 2008; 376:1348-59. [PMID: 18234218 DOI: 10.1016/j.jmb.2007.12.050] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 12/17/2007] [Accepted: 12/20/2007] [Indexed: 10/22/2022]
Abstract
In this study, we report the X-ray crystal structure of an N-terminally truncated variant of the bacterial serpin, tengpin (tengpinDelta42). Our data reveal that tengpinDelta42 adopts a variation of the latent conformation in which the reactive center loop is hyperinserted into the A beta-sheet and removed from the vicinity of the C-sheet. This conformational change leaves the C beta-sheet completely exposed and permits antiparallel edge-strand interactions between the exposed portion of the reactive center loop of one molecule and strand s2C of the C beta-sheet of the neighboring molecule in the crystal lattice. Our structural data thus reveal that tengpinDelta42 forms a loop C-sheet polymer in the crystal lattice. In vivo serpins have a propensity to misfold and form long-chain polymers, a process that underlies serpinopathies such as emphysema, thrombosis and dementia. Native serpins are thought to polymerize via a loop A-sheet mechanism. However, studies on plasminogen activator inhibitor 1 and the S49P variant of human neuroserpin reveal that the latent form of these molecules can also polymerize. Polymerization of latent neuroserpin may be important for the development of familial encephalopathy with neuroserpin inclusion bodies. Our structural data provide a possible mechanism for polymerization by latent serpins.
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Affiliation(s)
- Qingwei Zhang
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, VIC 3800, Australia
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22
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pH Induces Thermal Unfolding of UTI: An Implication of Reversible and Irreversible Mechanism Based on the Analysis of Thermal Stability, Thermodynamic, Conformational Characterization. J Fluoresc 2007; 18:305-17. [DOI: 10.1007/s10895-007-0270-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Accepted: 10/08/2007] [Indexed: 11/26/2022]
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23
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Paterson M, Horvath A, Pike R, Coughlin P. Molecular characterization of centerin, a germinal centre cell serpin. Biochem J 2007; 405:489-94. [PMID: 17447896 PMCID: PMC2267310 DOI: 10.1042/bj20070174] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Centerin [SERPINA9/GCET1 (germinal centre B-cell-expressed transcript 1)] is a serpin (serine protease inhibitor) whose expression is restricted to germinal centre B-cells and lymphoid malignancies with germinal centre B-cell maturation. Expression of centerin, together with bcl-6 and GCET2, constitutes a germinal centre B-cell signature, which is associated with a good prognosis in diffuse large B-cell lymphomas, but the molecular basis for this remains to be elucidated. We report here the cloning, expression and molecular characterization of bacterial recombinant centerin. Biophysical studies demonstrated that centerin was able to undergo the 'stressed to relaxed' conformational change which is an absolute requirement for protease inhibitory activity. Kinetic analysis showed that centerin rapidly inhibited the serine protease trypsin (k(a)=1.9x10(5) M(-1) x s(-1)) and also demonstrated measurable inhibition of thrombin (k(a)=1.17x10(3) M(-1) x s(-1)) and plasmin (k(a)=1.92x10(3) M(-1) x s(-1)). Centerin also bound DNA and unfractionated heparin, although there was no functionally significant impact on the rate of inhibition. These results suggest that centerin is likely to function in vivo in the germinal centre as an efficient inhibitor of a trypsin-like protease.
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Affiliation(s)
- Melinda A. Paterson
- *Australian Centre for Blood Diseases, Monash University, Level 6 Burnet Tower, 89 Commercial Road, Melbourne 3004, VIC, Australia
| | - Anita J. Horvath
- *Australian Centre for Blood Diseases, Monash University, Level 6 Burnet Tower, 89 Commercial Road, Melbourne 3004, VIC, Australia
| | - Robert N. Pike
- †Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton 3800, VIC, Australia
| | - Paul B. Coughlin
- *Australian Centre for Blood Diseases, Monash University, Level 6 Burnet Tower, 89 Commercial Road, Melbourne 3004, VIC, Australia
- To whom correspondence should be addressed (email )
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24
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Stanley P, Serpell L, Stein P. Polymerization of human angiotensinogen: insights into its structural mechanism and functional significance. Biochem J 2006; 400:169-78. [PMID: 16872275 PMCID: PMC1635450 DOI: 10.1042/bj20060444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study, we have investigated the in vitro polymerization of human plasma AGT (angiotensinogen), a non-inhibitory member of the serpin (SERine Protease INhibitor) family. Polymerization of AGT is thought to contribute to a high molecular mass form of the protein in plasma that is increased in pregnancy and pregnancy-associated hypertension. The results of the present study demonstrate that the polymerization of AGT occurs through a novel mechanism which is primarily dependent on non-covalent linkages, while additional disulfide linkages formed after prolonged incubation are not essential for either formation or stability of polymers. We present the first analyses of AGT polymers by electron microscopy, CD spectroscopy, stability assays and sensitivity to proteinases and we conclude that their structure differs from the 'loop-sheet' polymers typical of inhibitory serpins. Histidine residues within the unique N-terminal extension of AGT appear to influence polymer formation, although polymer formation can still take place after their removal by renin. At a functional level, we show that AGT polymers are not substrates for renin, so polymerization of AGT in plasma would predictably lead to decreased formation of AngI (angiotensin I) with blood pressure lowering. Polymerization may therefore be an appropriate response to hypertension. The ability of AGT to protect its renin cleavage site through polymerization may explain why the AngI decapeptide has remained linked to the large and apparently inactive serpin body throughout evolution.
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Affiliation(s)
- Peter Stanley
- *Division of Structural Medicine, Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge, CB2 2XY, U.K
| | - Louise C. Serpell
- †Department of Biochemistry, School of Life Sciences, University of Sussex, Falmer, E. Sussex. U.K
| | - Penelope E. Stein
- *Division of Structural Medicine, Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Cambridge, CB2 2XY, U.K
- To whom correspondence should be addressed (email )
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25
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Whisstock JC, Bottomley SP. Molecular gymnastics: serpin structure, folding and misfolding. Curr Opin Struct Biol 2006; 16:761-8. [PMID: 17079131 DOI: 10.1016/j.sbi.2006.10.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 09/10/2006] [Accepted: 10/19/2006] [Indexed: 11/25/2022]
Abstract
The native state of serpins represents a long-lived intermediate or metastable structure on the serpin folding pathway. Upon interaction with a protease, the serpin trap is sprung and the molecule continues to fold into a more stable conformation. However, thermodynamic stability can also be achieved through alternative, unproductive folding pathways that result in the formation of inactive conformations. Our increasing understanding of the mechanism of protease inhibition and the dynamics of native serpin structures has begun to reveal how evolution has harnessed the actual process of protein folding (rather than the final folded outcome) to elegantly achieve function. The cost of using metastability for function, however, is an increased propensity for misfolding.
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Affiliation(s)
- James C Whisstock
- Protein Crystallography Unit, Department of Biochemistry and Molecular Biology, Clayton Campus, Melbourne 3800, Australia.
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26
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Marszal E, Shrake A. Serpin crystal structure and serpin polymer structure. Arch Biochem Biophys 2006; 453:123-9. [PMID: 16631102 DOI: 10.1016/j.abb.2006.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Accepted: 03/05/2006] [Indexed: 11/25/2022]
Abstract
Serpins are a family of structurally homologous proteins having metastable native structures. As a result, a serpin variant destabilized by mutation(s) has a tendency to undergo conformational changes leading to inactive forms, e.g., the latent form and polymer. Serpin polymers are involved in a number of conformational diseases. Although several models for polymer structure have been proposed, the actual structure remains unknown. Here, we provide a comprehensive list of serpins, both free and in complexes, deposited in the Protein Data Bank. Our discussion focuses on structures that potentially can contribute to a better understanding of polymer structure.
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Affiliation(s)
- Ewa Marszal
- Division of Hematology, Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
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27
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McGowan S, Buckle AM, Irving JA, Ong PC, Bashtannyk-Puhalovich TA, Kan WT, Henderson KN, Bulynko YA, Popova EY, Smith AI, Bottomley SP, Rossjohn J, Grigoryev SA, Pike RN, Whisstock JC. X-ray crystal structure of MENT: evidence for functional loop-sheet polymers in chromatin condensation. EMBO J 2006; 25:3144-55. [PMID: 16810322 PMCID: PMC1500978 DOI: 10.1038/sj.emboj.7601201] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 05/22/2006] [Indexed: 11/09/2022] Open
Abstract
Most serpins are associated with protease inhibition, and their ability to form loop-sheet polymers is linked to conformational disease and the human serpinopathies. Here we describe the structural and functional dissection of how a unique serpin, the non-histone architectural protein, MENT (Myeloid and Erythroid Nuclear Termination stage-specific protein), participates in DNA and chromatin condensation. Our data suggest that MENT contains at least two distinct DNA-binding sites, consistent with its simultaneous binding to the two closely juxtaposed linker DNA segments on a nucleosome. Remarkably, our studies suggest that the reactive centre loop, a region of the MENT molecule essential for chromatin bridging in vivo and in vitro, is able to mediate formation of a loop-sheet oligomer. These data provide mechanistic insight into chromatin compaction by a non-histone architectural protein and suggest how the structural plasticity of serpins has adapted to mediate physiological, rather than pathogenic, loop-sheet linkages.
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Affiliation(s)
- Sheena McGowan
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Ashley M Buckle
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - James A Irving
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Poh Chee Ong
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | | | - Wan-Ting Kan
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Kate N Henderson
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Yaroslava A Bulynko
- Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, Milton S Hershey Medical Center, Hershey, PA, USA
| | - Evgenya Y Popova
- Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, Milton S Hershey Medical Center, Hershey, PA, USA
| | - A Ian Smith
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Stephen P Bottomley
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Jamie Rossjohn
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Sergei A Grigoryev
- Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, Milton S Hershey Medical Center, Hershey, PA, USA
- Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, H171, Milton S Hershey Medical Center, PO Box 850, 500 University Drive, Hershey, PA 17033, USA. Tel.: +1 717 531 8588; Fax: +1 717 531 7072; E-mail:
| | - Robert N Pike
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Joint senior authors
| | - James C Whisstock
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Joint senior authors
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia. Tel.: +613 9905 3747; Fax: +613 9905 4699; E-mail:
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28
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Sharp LK, Mallya M, Kinghorn KJ, Wang Z, Crowther DC, Huntington JA, Belorgey D, Lomas DA. Sugar and alcohol molecules provide a therapeutic strategy for the serpinopathies that cause dementia and cirrhosis. FEBS J 2006; 273:2540-52. [PMID: 16704419 DOI: 10.1111/j.1742-4658.2006.05262.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mutations in neuroserpin and alpha1-antitrypsin cause these proteins to form ordered polymers that are retained within the endoplasmic reticulum of neurones and hepatocytes, respectively. The resulting inclusions underlie the dementia familial encephalopathy with neuroserpin inclusion bodies (FENIB) and Z alpha1-antitrypsin-associated cirrhosis. Polymers form by a sequential linkage between the reactive centre loop of one molecule and beta-sheet A of another, and strategies that block polymer formation are likely to be successful in treating the associated disease. We show here that glycerol, the sugar alcohol erythritol, the disaccharide trehalose and its breakdown product glucose reduce the rate of polymerization of wild-type neuroserpin and the Ser49Pro mutant that causes dementia. They also attenuate the polymerization of the Z variant of alpha1-antitrypsin. The effect on polymerization was apparent even when these agents had been removed from the buffer. None of these agents had any detectable effect on the structure or inhibitory activity of neuroserpin or alpha1-antitrypsin. These data demonstrate that sugar and alcohol molecules can reduce the polymerization of serpin mutants that cause disease, possibly by binding to and stabilizing beta-sheet A.
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29
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Wang H, Pap S, Wiman B. Structures of importance for the stability of antiplasmin as studied by site-directed mutagenesis. Thromb Res 2006; 117:315-22. [PMID: 16378834 DOI: 10.1016/j.thromres.2005.02.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Revised: 02/25/2005] [Accepted: 02/25/2005] [Indexed: 11/28/2022]
Abstract
Human antiplasmin, a fast-acting inhibitor of plasmin in plasma, belongs to the serpin super-family of proteins. Like other members of this family, antiplasmin has a scissile peptide bond exposed within a reactive centre loop, typically present at the surface of the molecule. Antiplasmin is stable at neutral pH, but at acidic pH or at elevated temperatures it rapidly becomes inactivated. Data regarding "native" antiplasmin have demonstrated that both polymerization processes and formation of latent molecules are important in this respect. In this work we used site-directed mutagenesis to produce 11 single-site mutants (mainly within Abeta-sheet, Bbeta-sheet and reactive centre loop), which were expressed in Drosophila S2 cells, purified and characterized. Five of the 11 mutants were found to have a deviating stability at decreased pH. Glu346Thr was the only mutant with a lesser stability as compared to wt-antiplasmin, but the other 4 were more stable. The most stable mutant, His341Thr, was 7-fold more stable at pH 4.9 as compared to wt-antiplasmin. The wt-antiplasmin had a much more pronounced tendency to polymerize at decreased pH, as compared to "native" antiplasmin. However, many of the mutants clearly rather formed latent molecules, as judged both from PAGE-analysis at non-denaturing condition and reactivation experiments.
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Affiliation(s)
- Haiyao Wang
- Department of Clinical Chemistry and Blood Coagulation, Karolinska University Hospital, Karolinska Institute, SE-171 76 Stockholm, Sweden
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30
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Benning LN, Whisstock JC, Sun J, Bird PI, Bottomley SP. The human serpin proteinase inhibitor-9 self-associates at physiological temperatures. Protein Sci 2005; 13:1859-64. [PMID: 15215529 PMCID: PMC2279926 DOI: 10.1110/ps.04715304] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The metastable serpin architecture is perturbed by extremes of temperature, pH, or changes in primary sequence resulting in the formation of inactive, polymeric conformations. Polymerization of a number of human serpins in vivo leads to diseases such as emphysema, thrombosis, and dementia, and in these cases mutations are present within the gene encoding the aggregating protein. Here we show that aggregation of the human serpin, proteinase inhibitor-9 (PI-9), occurs under physiological conditions, and forms aggregates that are morphologically distinct from previously characterized serpin polymers. Incubation of monomeric PI-9 at 37 degrees C leads to the rapid formation of aggregated PI-9. Using a variety of spectroscopic methods we analyzed the nature of the structures formed after incubation at 37 degrees C. Electron microscopy showed that PI-9 forms ordered circular and elongated-type aggregates, which also bind the fluorescent dye Thioflavin T. Our data show that in vitro wild-type PI-9 forms aggregates at physiological temperatures. The biological implications of PI-9 aggregates at physiological temperatures are discussed.
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Affiliation(s)
- Lauren N Benning
- Department of Biochemistry and Molecular Biology, Monash University, P.O. Box 13D, Clayton, Victoria 3800, Australia
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31
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Differential detection of PAS-positive inclusions formed by the Z, Siiyama, and Mmalton variants of alpha1-antitrypsin. Hepatology 2004; 40:1203-10. [PMID: 15486938 DOI: 10.1002/hep.20451] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Several point mutations of alpha(1)-antitrypsin cause a perturbation in protein structure with consequent polymerization and intracellular accumulation. The retention of polymers of alpha(1)-antitrypsin within hepatocytes results in protein overload that in turn is associated with juvenile hepatitis, cirrhosis, and hepatocellular carcinoma. The detection of alpha(1)-antitrypsin polymers and understanding the molecular basis of polymer formation is of considerable clinical importance. We have used a monoclonal antibody (ATZ11) that specifically recognizes a conformation-dependent neoepitope on polymerized alpha(1)-antitrypsin to detect polymers within hepatocytes of individuals with alpha(1)-antitrypsin deficiency. Paraffin-embedded liver tissue specimens were obtained from individuals who were homozygous for the Z (Glu342Lys), Mmalton (52Phe del), and Siiyama (Ser53Phe) alleles of alpha(1)-antitrypsin that result in hepatic inclusions and profound plasma deficiency. Immunohistological staining with a polyclonal anti-human alpha(1)-antitrypsin antibody showed hepatic inclusions in all 3 cases, while ATZ11 reacted with hepatic inclusions formed by only Z alpha(1)-antitrypsin. Polymers of plasma M and Z alpha(1)-antitrypsin prepared under different conditions in vitro and polymers of recombinant mutants of alpha(1)-antitrypsin demonstrated that the monoclonal antibody detected a neoepitope on the polymerized protein. It did not detect polymers formed by a recombinant shutter domain mutant (that mirrors the effects of the Siiyama and Mmalton variants), polymers formed by cleaving alpha(1)-antitrypsin at the reactive loop, or C-sheet polymers formed by heating alpha(1)-antitrypsin in citrate. In conclusion, the ATZ11 monoclonal antibody detects Z alpha(1)-antitrypsin in hepatic inclusions by detecting a neoepitope that is specific to the polymeric conformer and that is localized close to residue 342.
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Parfrey H, Dafforn TR, Belorgey D, Lomas DA, Mahadeva R. Inhibiting Polymerization. Am J Respir Cell Mol Biol 2004; 31:133-9. [PMID: 15016619 DOI: 10.1165/rcmb.2003-0276oc] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The Z variant of alpha1-antitrypsin (Z-AT) is present in 4% of Northern Europeans and is associated with liver cirrhosis and emphysema. Polymers accumulate within the hepatocyte and the subsequent plasma deficiency of AT renders the lungs susceptible to proteolysis and early onset emphysema. We have previously demonstrated that the Phe-Leu-Glu-Ala-Ile-Gly (6 mer) peptide specifically binds to Z-AT and inhibits polymerization. Here we present the first detailed biochemical study of the purified Z-AT-6 mer binary complex. Biochemical studies indicated that this complex was inactive as a proteinase inhibitor and the peptide annealed to beta-sheet A of Z-AT. Removal of the N-acetyl terminus of the 6 mer peptide did not affect the peptide's ability to prevent polymer formation. However, the nonacetylated 6 mer-Z-AT complex dissociated at a rate 2.75 x faster than the acetylated 6 mer-Z-AT complex to yield an active inhibitor; Koff 5.5 +/- 1.07 versus 2.0 +/- 0.25 10(6) s(-1), respectively. These biochemical data indicate a potential therapeutic approach whereby polymerization is prevented in the liver, with the gradual release of the peptide from the binary complex restoring proteinase inhibitory function within the tissues. Thus, it raises the novel prospect of ameliorating both the cirrhosis and the emphysema associated with Z-AT.
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Affiliation(s)
- Helen Parfrey
- Division of Respiratory Medicine, Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, MRC/Wellcome Trust Building, Hills Road, Cambridge CB2 2XY, UK.
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33
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Lee HJ, Im H. Purification of recombinant plasminogen activator inhibitor-1 in the active conformation by refolding from inclusion bodies. Protein Expr Purif 2003; 31:99-107. [PMID: 12963346 DOI: 10.1016/s1046-5928(03)00160-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plasminogen activator inhibitor-1 (PAI-1) acts as the major inhibitor of fibrinolysis by inhibiting tissue-type and urokinase-type plasminogen activators. Although it shares a common tertiary structure with other serine protease inhibitors, PAI-1 is unique in its conformational lability, which allows conversion of the active form to the latent conformation under physiological conditions. Therefore, recombinant PAI-1 expressed in eukaryotic or prokaryotic cells almost always contains its inactive, latent form, with very low specific activity. In this study, we developed a simple and efficient method for purifying the active form of recombinant PAI-1 rather than the latent conformation from PAI-1 overexpressing Escherichia coli cells. The overall level of expression and the amount of PAI-1 found in inclusion bodies were found to increase with culture temperature and with time after induction. Refolding of unfolded PAI-1 from inclusion bodies and ion-exchange column chromatography were sufficient to purify PAI-1. The purified protein yielded a single, 43kDa protein band upon SDS-polyacrylamide gel electrophoresis, and it efficiently inhibited tissue-type and urokinase-type plasminogen activators similar to PAI-1 from natural sources. Activity measurements showed that PAI-1 purified from inclusion bodies exhibited a specific activity near the theoretical maximum, unlike PAI-1 prepared from cytosolic fractions. Conformational analysis by urea gel electrophoresis also indicated that the PAI-1 protein purified from inclusion bodies was indeed in its active conformation.
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Affiliation(s)
- Hak-Joo Lee
- Department of Molecular Biology, Sejong University, 98 Gunja-dong, Kwangjin-gu, 143-747, Seoul, South Korea
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34
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Einholm AP, Pedersen KE, Wind T, Kulig P, Overgaard MT, Jensen JK, Bødker JS, Christensen A, Charlton P, Andreasen PA. Biochemical mechanism of action of a diketopiperazine inactivator of plasminogen activator inhibitor-1. Biochem J 2003; 373:723-32. [PMID: 12723974 PMCID: PMC1223537 DOI: 10.1042/bj20021880] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2002] [Revised: 03/27/2003] [Accepted: 04/30/2003] [Indexed: 11/17/2022]
Abstract
XR5118 [(3 Z,6 Z )-6-benzylidine-3-(5-(2-dimethylaminoethyl-thio-))-2-(thienyl)methylene-2,5-dipiperazinedione hydrochloride] can inactivate the anti-proteolytic activity of the serpin plasminogen activator inhibitor-1 (PAI-1), a potential therapeutic target in cancer and cardiovascular diseases. Serpins inhibit their target proteases by the P(1) residue of their reactive centre loop (RCL) forming an ester bond with the active-site serine residue of the protease, followed by insertion of the RCL into the serpin's large central beta-sheet A. In the present study, we show that the RCL of XR5118-inactivated PAI-1 is inert to reaction with its target proteases and has a decreased susceptibility to non-target proteases, in spite of a generally increased proteolytic susceptibility of specific peptide bonds elsewhere in PAI-1. The properties of XR5118-inactivated PAI-1 were different from those of the so-called latent form of PAI-1. Alanine substitution of several individual residues decreased the susceptibility of PAI-1 to XR5118. The localization of these residues in the three-dimensional structure of PAI-1 suggested that the XR5118-induced inactivating conformational change requires mobility of alpha-helix F, situated above beta-sheet A, and is in agreement with the hypothesis that XR5118 binds laterally to beta-sheet A. These results improve our understanding of the unique conformational flexibility of serpins and the biochemical basis for using PAI-1 as a therapeutic target.
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Affiliation(s)
- Anja P Einholm
- Department of Molecular Biology, Aarhus University, 10C Gustav Wied's Vej, 8000 C Aarhus, Denmark
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35
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Marszal E, Danino D, Shrake A. A novel mode of polymerization of alpha1-proteinase inhibitor. J Biol Chem 2003; 278:19611-8. [PMID: 12649292 DOI: 10.1074/jbc.m210720200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Patients homozygous for the Z mutant form of alpha1-proteinase inhibitor (alpha1-PI) have an increased risk for the development of liver disease because of the accumulation in hepatocytes of inclusion bodies containing linear polymers of mutant alpha1-PI. The most widely accepted model of polymerization proposes that a linear, head-to-tail polymer forms by sequential insertion of the reactive center loop (RCL) of one alpha1-PI monomer between the central strands of the A beta-sheet of an adjacent monomer. This model derives primarily from two observations: peptides that are homologous with the RCL insert into the A beta-sheet of alpha1-PI monomer and this insertion prevents alpha1-PI polymerization. Normal alpha1-PI monomer does not spontaneously polymerize; however, here we show that the disulfide-linked dimer of normal alpha1-PI spontaneously forms linear polymers in buffer. The monomers within this dimer are joined head-to-head. Thus, the arrangement of monomers in these polymers must be different from that predicted by the loop-A sheet model. Therefore, we propose a new model for alpha1-PI polymer. In addition, polymerization of disulfide-linked dimer is not inhibited by the presence of the peptide even though dimer appears to interact with the peptide. Thus, RCL insertion into A beta-sheets may not occur during polymerization of this dimer.
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Affiliation(s)
- Ewa Marszal
- Division of Hematology, Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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36
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Robertson AS, Belorgey D, Lilley KS, Lomas DA, Gubb D, Dafforn TR. Characterization of the necrotic protein that regulates the Toll-mediated immune response in Drosophila. J Biol Chem 2003; 278:6175-80. [PMID: 12414799 DOI: 10.1074/jbc.m209277200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Necrotic (Nec) is an important component of the proteolytic cascade that activates the Toll-mediated immune response in Drosophila. The Nec protein is a member of the serpin (SERine Protease INhibitor) superfamily and is thought to regulate the cascade by inhibiting the serine protease Persephone. Nec was expressed in Escherichia coli, and the purified protein folded to the active native conformation required for protease inhibitory activity. Biochemical analysis showed that Nec had a broad inhibitory specificity and inhibited elastase, thrombin, and chymotrypsin-like proteases. It did not inhibit trypsin or kallikrein. These data show that Necrotic is likely to inhibit a wide range of proteases in Drosophila and that Nec has the specificity requirements to act as the physiological inhibitor of Persephone in vivo.
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Affiliation(s)
- Andrew S Robertson
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, United Kingdom
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37
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Devlin GL, Chow MKM, Howlett GJ, Bottomley SP. Acid Denaturation of alpha1-antitrypsin: characterization of a novel mechanism of serpin polymerization. J Mol Biol 2002; 324:859-70. [PMID: 12460583 DOI: 10.1016/s0022-2836(02)01088-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The native serpin architecture is extremely sensitive to mutation and environmental factors. These factors induce the formation of a partially folded species that results in the production of inactive loop-sheet polymers. The deposition of these aggregates in tissue, results in diseases such as liver cirrhosis, thrombosis, angioedema and dementia. In this study, we characterize the kinetics and conformational changes of alpha(1)-antitrypsin polymerization at pH 4 using tryptophan fluorescence, circular dichroism, turbidity changes and thioflavin T binding. These biophysical techniques have demonstrated that polymerization begins with a reversible conformational change that results in partial loss of secondary structure and distortion at the top of beta-sheet A. This is followed by two bimolecular processes. First, protodimers are formed, which can be dissociated by changing the pH back to 8. Then, an irreversible conformational change occurs, resulting in the stabilization of the dimers with a concomitant increase in beta-sheet structure, allowing for subsequent polymer extension. Electron microscopy analysis of the polymers, coupled with the far-UV CD and thioflavin T properties of the pH 4 polymers suggest they do not form via the classical loop-beta-sheet A linkage. However, they more closely resemble those formed by the pathological variant M(malton). Taken together, these data describe a novel kinetic mechanism of serine proteinase inhibitor polymerization.
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Affiliation(s)
- Glyn L Devlin
- Department of Biochemistry and Molecular Biology, P.O. Box 13D, Monash University, 3800 Australia
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38
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Baglin TP, Carrell RW, Church FC, Esmon CT, Huntington JA. Crystal structures of native and thrombin-complexed heparin cofactor II reveal a multistep allosteric mechanism. Proc Natl Acad Sci U S A 2002; 99:11079-84. [PMID: 12169660 PMCID: PMC123213 DOI: 10.1073/pnas.162232399] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The serine proteases sequentially activated to form a fibrin clot are inhibited primarily by members of the serpin family, which use a unique beta-sheet expansion mechanism to trap and destroy their targets. Since the discovery that serpins were a family of serine protease inhibitors there has been controversy as to the role of conformational change in their mechanism. It now is clear that protease inhibition depends entirely on rapid serpin beta-sheet expansion after proteolytic attack. The regulatory advantage afforded by the conformational mobility of serpins is demonstrated here by the structures of native and S195A thrombin-complexed heparin cofactor II (HCII). HCII inhibits thrombin, the final protease of the coagulation cascade, in a glycosaminoglycan-dependent manner that involves the release of a sequestered hirudin-like N-terminal tail for interaction with thrombin. The native structure of HCII resembles that of native antithrombin and suggests an alternative mechanism of allosteric activation, whereas the structure of the S195A thrombin-HCII complex defines the molecular basis of allostery. Together, these structures reveal a multistep allosteric mechanism that relies on sequential contraction and expansion of the central beta-sheet of HCII.
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Affiliation(s)
- Trevor P Baglin
- Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
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39
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Belorgey D, Crowther DC, Mahadeva R, Lomas DA. Mutant Neuroserpin (S49P) that causes familial encephalopathy with neuroserpin inclusion bodies is a poor proteinase inhibitor and readily forms polymers in vitro. J Biol Chem 2002; 277:17367-73. [PMID: 11880376 DOI: 10.1074/jbc.m200680200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is an autosomal dominant dementia that is characterized by intraneuronal inclusions of mutant neuroserpin. We report here the expression, purification, and characterization of wild-type neuroserpin and neuroserpin containing the S49P mutation that causes FENIB. Wild-type neuroserpin formed SDS-stable complexes with tPA with an association rate constant and K(i) of 1.2 x 10(4) m(-1) s(-1) and 5.8 nm, respectively. In contrast, S49P neuroserpin formed unstable complexes with an association rate constant and K(i) of 0.3 x 10(4) m(-1) s(-1) and 533.3 nm, respectively. An assessment by circular dichroism showed that S49P neuroserpin had a lower melting temperature than wild-type protein (49.9 and 56.6 degrees C, respectively) and more readily formed loop-sheet polymers under physiological conditions. Neither the wild-type nor S49P neuroserpin accepted the P7-P2 alpha(1)-anti-trypsin or P14-P3 antithrombin-reactive loop peptides that have been shown to block polymer formation in other members of the serpin superfamily. Taken together, these data demonstrate that S49P neuroserpin is a poor proteinase inhibitor and readily forms loop-sheet polymers. These findings provide strong support for the role of neuroserpin polymerization in the formation of the intraneuronal inclusions that are characteristic of FENIB.
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Affiliation(s)
- Didier Belorgey
- Respiratory Medicine Unit and Neurology Unit, Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, United Kingdom.
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40
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Irving JA, Shushanov SS, Pike RN, Popova EY, Brömme D, Coetzer THT, Bottomley SP, Boulynko IA, Grigoryev SA, Whisstock JC. Inhibitory activity of a heterochromatin-associated serpin (MENT) against papain-like cysteine proteinases affects chromatin structure and blocks cell proliferation. J Biol Chem 2002; 277:13192-201. [PMID: 11821386 DOI: 10.1074/jbc.m108460200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
MENT (Myeloid and Erythroid Nuclear Termination stage-specific protein) is a developmentally regulated chromosomal serpin that condenses chromatin in terminally differentiated avian blood cells. We show that MENT is an effective inhibitor of the papain-like cysteine proteinases cathepsins L and V. In addition, ectopic expression of MENT in mammalian cells is apparently sufficient to inhibit a nuclear papain-like cysteine proteinase and prevent degradation of the retinoblastoma protein, a major regulator of cell proliferation. MENT also accumulates in the nucleus, causes a strong block in proliferation, and promotes condensation of chromatin. Variants of MENT with mutations or deletions within the M-loop, which contains a nuclear localization signal and an AT-hook motif, reveal that this region mediates nuclear transport and morphological changes associated with chromatin condensation. Non-inhibitory mutants of MENT were constructed to determine whether its inhibitory activity has a role in blocking proliferation. These mutations changed the mode of association with chromatin and relieved the block in proliferation, without preventing transport to the nucleus. We conclude that the repressive effect of MENT on chromatin is mediated by its direct interaction with a nuclear protein that has a papain-like cysteine proteinase active site.
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Affiliation(s)
- James A Irving
- Department of Biochemistry and Molecular Biology, Clayton Campus, Monash University, P. O. Box 13D, Victoria 3800, Australia
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41
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Belzar KJ, Zhou A, Carrell RW, Gettins PGW, Huntington JA. Helix D elongation and allosteric activation of antithrombin. J Biol Chem 2002; 277:8551-8. [PMID: 11741963 DOI: 10.1074/jbc.m110807200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antithrombin requires allosteric activation by heparin for efficient inhibition of its target protease, factor Xa. A pentasaccharide sequence found in heparin activates antithrombin by inducing conformational changes that affect the reactive center of the inhibitor resulting in optimal recognition by factor Xa. The mechanism of transmission of the activating conformational change from the heparin-binding region to the reactive center loop remains unresolved. To investigate the role of helix D elongation in the allosteric activation of antithrombin, we substituted a proline residue for Lys(133). Heparin binding affinity was reduced by 25-fold for the proline variant compared with the control, and a significant decrease in the associated intrinsic fluorescence enhancement was also observed. Rapid kinetic studies revealed that the main reason for the reduced affinity for heparin was an increase in the rate of the reverse conformational change step. The pentasaccharide-accelerated rate of factor Xa inhibition for the proline variant was 10-fold lower than control, demonstrating that the proline variant cannot be fully activated toward factor Xa. We conclude that helix D elongation is critical for the full conversion of antithrombin to its high affinity, activated state, and we propose a mechanism to explain how helix D elongation is coupled to allosteric activation.
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Affiliation(s)
- Klara J Belzar
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Rd., Cambridge CB2 2XY, United Kingdom
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42
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Wind T, Hansen M, Jensen JK, Andreasen PA. The molecular basis for anti-proteolytic and non-proteolytic functions of plasminogen activator inhibitor type-1: roles of the reactive centre loop, the shutter region, the flexible joint region and the small serpin fragment. Biol Chem 2002; 383:21-36. [PMID: 11928815 DOI: 10.1515/bc.2002.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The serine proteinase inhibitor plasminogen activator inhibitor type-1 (PAI-1) is the primary physiological inhibitor of the tissue-type and the urokinase-type plasminogen activator (tPA and uPA, respectively) and as such an important regulator of proteolytic events taking place in the circulation and in the extracellular matrix. Moreover, a few non-proteolytic functions have been ascribed to PAI-1, mediated by its interaction with vitronectin or the interaction between the uPA-PAI-1 complex bound to the uPA receptor and members of the low density lipoprotein receptor family. PAI-1 belongs to the serpin family, characterised by an unusual conformational flexibility, which governs its molecular interactions. In this review we describe the anti-proteolytic and non-proteolytic functions of PAI-1 from both a biological and a biochemical point of view. We will relate the various biological roles of PAI-1 to its biochemistry in general and to the different conformations of PAI-1 in particular. We put emphasis on the intramolecular rearrangements of PAI-1 that are required for its antiproteolytic as well as its non-proteolytic functions.
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Affiliation(s)
- Troels Wind
- Department of Molecular and Structural Biology, Aarhus University, Denmark
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43
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Jerabek I, Zechmeister-Machhart M, Binder BR, Geiger M. Binding of retinoic acid by the inhibitory serpin protein C inhibitor. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:5989-96. [PMID: 11722589 DOI: 10.1046/j.0014-2956.2001.02560.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The serpin superfamily includes inhibitors of serine proteases and noninhibitory members with other functions (e.g. the hormone precursor angiotensinogen and the hormone carriers corticosteroid-binding globulin and thyroxine-binding globulin). It is not known whether inhibitory serpins have additional, noninhibitory functions. We studied binding of (3)H-labeled hydrophobic hormones (estradiol, progesterone, testosterone, cortisol, aldosterone, and all-trans-retinoic acid) to the inhibitory serpins antithrombin III, heparin cofactor II, plasminogen activator inhibitor-1, and protein C inhibitor (PCI). All-trans-[(3)H]retinoic acid bound in a specific dose-dependent and time-dependent way to PCI (apparent K(d) = 2.43 microm, 0.8 binding sites per molecule of PCI). We did not observe binding of other hormones to serpins. Intact and protease-cleaved PCI bound retinoic acid equally well, and retinoic acid did not influence inhibition of tissue kallikrein by PCI. Gel filtration confirmed binding of retinoic acid to PCI in purified systems and suggested that PCI may also function as a retinoic acid-binding protein in seminal plasma. Therefore, our present data, together with the fact that PCI is abundantly expressed in tissues requiring retinoic acid for differentiation processes (e.g. the male reproductive tract, epithelia in various organs), suggest an additional biological role for PCI as a retinoic acid-binding and/or delivering serpin.
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Affiliation(s)
- I Jerabek
- Department of Vascular Biology and Thrombosis Research, University of Vienna, Austria
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44
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Zhou A, Carrell RW, Huntington JA. The serpin inhibitory mechanism is critically dependent on the length of the reactive center loop. J Biol Chem 2001; 276:27541-7. [PMID: 11325972 DOI: 10.1074/jbc.m102594200] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The recent crystallographic structure of a serpin-protease complex revealed that protease inactivation results from a disruption of the catalytic site architecture caused by the displacement of the catalytic serine. We hypothesize that inhibition depends on the length of the N-terminal portion of the reactive center loop, to which the active serine is covalently attached. To test this, alpha(1)-antitrypsin Pittsburgh variants were prepared with lengthened and shortened reactive center loops. The rates of inhibition of factor Xa and of complex dissociation were measured. The addition of one residue reduced the stability of the complex more than 200,000-fold, and the addition of two residues reduced it by more than 1,000,000-fold, whereas the deletion of one or two residues lowered the efficiency of inhibition and increased the stability of the complex (2-fold). The deletion of more than two residues completely converted the serpin into a substrate. Similar results were obtained for the alpha(1)-antitrypsin variants with thrombin and for PAI-1 and PAI-2 with their common target tissue plasminogen activator. We conclude that the length of the serpin reactive center loop is critical for its mechanism of inhibition and is precisely regulated to balance the efficiency of inhibition and stability of the final complex.
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Affiliation(s)
- A Zhou
- Department of Haematology, University of Cambridge, Wellcome Trust Center for Molecular Mechanisms in Disease, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY, United Kingdom
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45
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Egelund R, Einholm AP, Pedersen KE, Nielsen RW, Christensen A, Deinum J, Andreasen PA. A regulatory hydrophobic area in the flexible joint region of plasminogen activator inhibitor-1, defined with fluorescent activity-neutralizing ligands. Ligand-induced serpin polymerization. J Biol Chem 2001; 276:13077-86. [PMID: 11278457 DOI: 10.1074/jbc.m009024200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have characterized the neutralization of the inhibitory activity of the serpin plasminogen activator inhibitor-1 (PAI-1) by a number of structurally distinct organochemicals, including compounds with environment-sensitive spectroscopic properties. In contrast to latent and reactive center-cleaved PAI-1 and PAI-1 in complex with urokinase-type plasminogen activator (uPA), active PAI-1 strongly increased the fluorescence of the PAI-1-neutralizing compounds 1-anilinonaphthalene-8-sulfonic acid and 4,4'-dianilino-1,1'-bisnaphthyl-5,5'-disulfonic acid. The fluorescence increase could be competed by all tested nonfluorescent neutralizers, indicating that all neutralizers bind to a common hydrophobic area preferentially accessible in active PAI-1. Activity neutralization proceeded through two consecutive steps as follows: first step is conversion to forms displaying substrate behavior toward uPA, and second step is to forms inert to uPA. With some neutralizers, the second step was associated with PAI-1 polymerization. Vitronectin reduced the susceptibility to the neutralizers. Changes in sensitivity to activity neutralization by point mutations were compatible with the various neutralizers having overlapping, but not identical, binding sites in the region around alpha-helices D and E and beta-strand 1A, known to act as a flexible joint when beta-sheet A opens and the reactive center loop inserts as beta-strand 4A during reaction with target proteinases. The defined binding area may be a target for development of compounds for neutralizing PAI-1 in cancer and cardiovascular diseases.
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Affiliation(s)
- R Egelund
- Laboratory of Cellular Protein Science, Department of Molecular and Structural Biology, Aarhus University, 8000 Aarhus C, Denmark
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