1
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Garrido-Rodríguez P, Carmena-Bargueño M, de la Morena-Barrio ME, Bravo-Pérez C, de la Morena-Barrio B, Cifuentes-Riquelme R, Lozano ML, Pérez-Sánchez H, Corral J. Analysis of AlphaFold and molecular dynamics structure predictions of mutations in serpins. PLoS One 2024; 19:e0304451. [PMID: 38968282 PMCID: PMC11226102 DOI: 10.1371/journal.pone.0304451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 05/13/2024] [Indexed: 07/07/2024] Open
Abstract
Serine protease inhibitors (serpins) include thousands of structurally conserved proteins playing key roles in many organisms. Mutations affecting serpins may disturb their conformation, leading to inactive forms. Unfortunately, conformational consequences of serpin mutations are difficult to predict. In this study, we integrate experimental data of patients with mutations affecting one serpin with the predictions obtained by AlphaFold and molecular dynamics. Five SERPINC1 mutations causing antithrombin deficiency, the strongest congenital thrombophilia were selected from a cohort of 350 unrelated patients based on functional, biochemical, and crystallographic evidence supporting a folding defect. AlphaFold gave an accurate prediction for the wild-type structure. However, it also produced native structures for all variants, regardless of complexity or conformational consequences in vivo. Similarly, molecular dynamics of up to 1000 ns at temperatures causing conformational transitions did not show significant changes in the native structure of wild-type and variants. In conclusion, AlphaFold and molecular dynamics force predictions into the native conformation at conditions with experimental evidence supporting a conformational change to other structures. It is necessary to improve predictive strategies for serpins that consider the conformational sensitivity of these molecules.
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Affiliation(s)
- Pedro Garrido-Rodríguez
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - Miguel Carmena-Bargueño
- Structural Bioinformatics & High Performance Computing Research Group (BIO-HPC), Universidad Católica de Murcia (UCAM), Murcia, Spain
| | - María Eugenia de la Morena-Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - Carlos Bravo-Pérez
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - Belén de la Morena-Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - Rosa Cifuentes-Riquelme
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - María Luisa Lozano
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
| | - Horacio Pérez-Sánchez
- Structural Bioinformatics & High Performance Computing Research Group (BIO-HPC), Universidad Católica de Murcia (UCAM), Murcia, Spain
| | - Javier Corral
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-ISCIII, Murcia, Spain
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2
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Grover SP, Mackman N. Anticoagulant SERPINs: Endogenous Regulators of Hemostasis and Thrombosis. Front Cardiovasc Med 2022; 9:878199. [PMID: 35592395 PMCID: PMC9110684 DOI: 10.3389/fcvm.2022.878199] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/29/2022] [Indexed: 12/17/2022] Open
Abstract
Appropriate activation of coagulation requires a balance between procoagulant and anticoagulant proteins in blood. Loss in this balance leads to hemorrhage and thrombosis. A number of endogenous anticoagulant proteins, such as antithrombin and heparin cofactor II, are members of the serine protease inhibitor (SERPIN) family. These SERPIN anticoagulants function by forming irreversible inhibitory complexes with target coagulation proteases. Mutations in SERPIN family members, such as antithrombin, can cause hereditary thrombophilias. In addition, low plasma levels of SERPINs have been associated with an increased risk of thrombosis. Here, we review the biological activities of the different anticoagulant SERPINs. We further consider the clinical consequences of SERPIN deficiencies and insights gained from preclinical disease models. Finally, we discuss the potential utility of engineered SERPINs as novel therapies for the treatment of thrombotic pathologies.
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3
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Abstract
Commercially available products used for antithrombin supplementation, for example, in extracorporeal life support, may contain latent antithrombin, a hyper-stable strongly procoagulative and anti-angiogenic residue. Latent antithrombin is associated with severe thrombosis in the critically ill. In the manufacturing process of fractionated antithrombin from plasma, heat treatment, citrate, and freeze drying speed up the transformation of native antithrombin to latent antithrombin. Manufacturers are not required to assess and report the latent antithrombin content of their products. When reported, the latent antithrombin fractions in their product range from <1% to 40% of total antithrombin compared with <3% in the healthy adult and less in children. The aims of this work were (1) to convey increased awareness to clinicians who may experience defaulted, expected effect after antithrombin supplementation in, for example, heparin anticoagulation during extracorporeal life support and (2) to urge manufacturers to assess and disclose latent antithrombin content in their products.
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Affiliation(s)
- Lars Mikael Broman
- ECMO Centre Karolinska, Pediatric Perioperative Medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden.,Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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4
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Morrisette MJ, Zomp-Wiebe A, Bidwell KL, Dunn SP, Gelvin MG, Money DT, Palkimas S. Antithrombin supplementation in adult patients receiving extracorporeal membrane oxygenation. Perfusion 2019; 35:66-72. [PMID: 31213179 DOI: 10.1177/0267659119856229] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Extracorporeal membrane oxygenation is associated with an increased risk of thrombosis and hemorrhage. Acquired antithrombin deficiency often occurs in patients receiving extracorporeal membrane oxygenation, necessitating supplementation to restore adequate anticoagulation. Criteria for antithrombin supplementation in adult extracorporeal membrane oxygenation patients are not well defined. METHODS In this retrospective observational study, adult patients receiving antithrombin supplementation while supported on extracorporeal membrane oxygenation were evaluated. Antithrombin was supplemented when anti-Xa levels were subtherapeutic with unfractionated heparin infusion rates of 15-20 units/kg/h and measured antithrombin activity <50%. Patients were evaluated for changes in degree of anticoagulation and signs of bleeding 24 hours pre- and post-antithrombin supplementation. RESULTS A total of 14 patients received antithrombin supplementation while on extracorporeal membrane oxygenation. The median percentage of time therapeutic anti-Xa levels were maintained was 0% (0-43%) and 40% (9-84%) in the pre-antithrombin and post-antithrombin groups, respectively (p = 0.13). No difference was observed in the number of patients attaining a single therapeutic anti-Xa level (pre-antithrombin = 6, post-antithrombin = 13; p = 0.37) or unfractionated heparin infusion rate (pre-antithrombin = 7.35 (1.95-10.71) units/kg/h, post-antithrombin = 6.81 (3.45-12.58) units/kg/h; p = 0.33). Thirteen patients (92%) achieved an antithrombin activity at goal following supplementation. Antithrombin activity was maintained within goal range 52% of the time during the replacement period. Four bleeding events occurred pre-antithrombin and 10 events post-antithrombin administration (p = 0.26) with significantly more platelets administered post-antithrombin (pre-antithrombin = 0.5 units, post-antithrombin = 4.5 units; p = 0.01). CONCLUSION Therapeutic anticoagulation occurred more frequently following antithrombin supplementation; however, this difference was not statistically significant. More bleeding events occurred following antithrombin supplementation while observing an increase in platelet transfusions.
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Affiliation(s)
- Matthew J Morrisette
- Department of Pharmacy Services, University of Virginia Health System, Charlottesville, VA, USA
| | - Amanda Zomp-Wiebe
- Department of Pharmacy Services, University of Virginia Health System, Charlottesville, VA, USA
| | - Katherine L Bidwell
- Department of Pharmacy Services, University of Virginia Health System, Charlottesville, VA, USA
| | - Steven P Dunn
- Department of Pharmacy Services, University of Virginia Health System, Charlottesville, VA, USA
| | - Michael G Gelvin
- Department of Thoracic and Cardiovascular Perfusion, University of Virginia, Charlottesville, VA, USA
| | - Dustin T Money
- Department of Thoracic and Cardiovascular Perfusion, University of Virginia, Charlottesville, VA, USA
| | - Surabhi Palkimas
- Department of Pharmacy Services, University of Virginia Health System, Charlottesville, VA, USA
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5
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Biochemical and cellular consequences of the antithrombin p.Met1? mutation identified in a severe thrombophilic family. Oncotarget 2018; 9:33202-33214. [PMID: 30237862 PMCID: PMC6145704 DOI: 10.18632/oncotarget.26059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 07/31/2018] [Indexed: 11/25/2022] Open
Abstract
Nature is always the best inspiration for basic research. A family with severe thrombosis and antithrombin deficiency, the strongest anticoagulant, carried a new mutation affecting the translation-start codon of SERPINC1, the gene encoding antithrombin. Expression of this variant in a eukaryotic cell system produced three different antithrombins. Two downstream methionines were used as alternative initiation codons, generating highly expressed small aglycosylated antithrombins with cytoplasmic localization. Wild-type antithrombin was generated by the use of the mutated AUU as initiation codon. Actually, any codon except for the three stop codons might be used to initiate translation in this strong Kozak context. We show unexpected consequences of natural mutations affecting translation-start codons. Downstream alternative initiation AUG codons may be used when the start codon is mutated, generating smaller molecules with potential different cell localization, biochemical features and unexplored consequences. Additionally, our data further support the use of other codons apart from AUG for initiation of translation in eukaryotes.
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6
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Corral J, de la Morena-Barrio ME, Vicente V. The genetics of antithrombin. Thromb Res 2018; 169:23-29. [DOI: 10.1016/j.thromres.2018.07.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 07/02/2018] [Accepted: 07/04/2018] [Indexed: 11/16/2022]
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7
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Wang G, Bondarenko PV, Kaltashov IA. Multi-step conformational transitions in heat-treated protein therapeutics can be monitored in real time with temperature-controlled electrospray ionization mass spectrometry. Analyst 2018; 143:670-677. [PMID: 29303166 DOI: 10.1039/c7an01655g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heat-induced conformational transitions are frequently used to probe the free energy landscapes of proteins. However, the extraction of information from thermal denaturation profiles pertaining to non-native protein conformations remains challenging due to their transient nature and significant conformational heterogeneity. Previously we developed a temperature-controlled electrospray ionization (ESI) source that allowed unfolding and association of biopolymers to be monitored by mass spectrometry (MS) in real time as a function of temperature. The scope of this technique is now extended to systems that undergo multi-step denaturation upon heat stress, as well as relatively small-scale conformational changes that are precursors to protein aggregation. The behavior of two therapeutic proteins (human antithrombin and an IgG1 monoclonal antibody) under heat-stress conditions is monitored in real time, providing evidence that relatively small-scale conformational changes in each system lead to protein oligomerization, followed by aggregation. Temperature-controlled ESI MS is particularly useful for the studies of heat-stressed multi-domain proteins such as IgG, where it allows distinct transitions to be observed. The ability of native temperature-controlled ESI MS to monitor both the conformational changes and oligomerization/degradation with high selectivity complements the classic calorimetric methods, lending itself as a powerful experimental tool for the thermostability studies of protein therapeutics.
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Affiliation(s)
- Guanbo Wang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, and School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu, China.
| | - Pavel V Bondarenko
- Attribute Sciences, Process Development, Amgen, Inc., Thousand Oaks, CA, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
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8
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Yang L, Rezaie AR. Characterization of Protein Z-Dependent Protease Inhibitor/Antithrombin Chimeras Provides Insight into the Serpin Specificity of Coagulation Proteases. ACS OMEGA 2017; 2:3276-3283. [PMID: 28782047 PMCID: PMC5537704 DOI: 10.1021/acsomega.7b00606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/28/2017] [Indexed: 06/07/2023]
Abstract
Protein Z (PZ)-dependent protease inhibitor (ZPI) and antithrombin (AT) are two physiological serpin inhibitors involved in the regulation of proteolytic activities of the blood coagulation cascade. ZPI has restricted protease specificity capable of inhibiting factors Xa (FXa) and XIa (FXIa) but exhibiting no reactivity with other coagulation proteases. Unlike ZPI, AT is a general inhibitor of all coagulation proteases and the only physiological inhibitor of factor IXa (FIXa). To understand the molecular determinants of protease specificity of the two serpins, we engineered two ZPI mutants in which the P12-P3' residues of the reactive center loop of ZPI were replaced with either P12-P3' or P12-P7' residues of AT (ZPI-ATP12-P3' and ZPI-ATP12-P7'). The reactivity of chimeras with FXa was improved ∼4-25-fold in the absence of PZ. Both chimeras inhibited FIXa with rate constants that were ∼2 orders of magnitude higher than the rate of the AT inhibition of the protease. PZ improved the reactivity of chimeras with FIXa by another 2 orders of magnitude, rendering the chimeras potent inhibitors of FIXa so that the PZ-mediated inhibitory activity of the ZPI-AT chimeras toward FIXa was ∼20-fold higher than that of the fondaparinux-catalyzed inhibition of FIXa by AT. Further studies revealed that the substitution of P1-Tyr of ZPI with an Arg is sufficient to convert the serpin to an effective inhibitor of FIXa. The potential therapeutic utility of the serpin chimeras as specific inhibitors of FIXa was diminished by findings that the chimeras function as effective substrates for other coagulation proteases.
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Affiliation(s)
- Likui Yang
- Cardiovascular
Biology Research Program, Oklahoma Medical
Research Foundation, Oklahoma
City, Oklahoma 73104, United States
| | - Alireza R. Rezaie
- Cardiovascular
Biology Research Program, Oklahoma Medical
Research Foundation, Oklahoma
City, Oklahoma 73104, United States
- Department
of Biochemistry and Molecular Biology, University
of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
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9
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de la Morena-Barrio M, Sandoval E, Llamas P, Wypasek E, Toderici M, Navarro-Fernández J, Rodríguez-Alen A, Revilla N, López-Gálvez R, Miñano A, Padilla J, de la Morena-Barrio B, Cuesta J, Corral J, Vicente V. High levels of latent antithrombin in plasma from patients with antithrombin deficiency. Thromb Haemost 2017; 117:880-888. [PMID: 28229161 DOI: 10.1160/th16-11-0866] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/02/2017] [Indexed: 11/05/2022]
Abstract
Antithrombin is an anticoagulant serpin that efficiently inhibits multiple procoagulant proteases. The cost for the structural flexibility required for this function is the vulnerability to mutations that impact its folding pathway. Most conformational mutations identified in serpins cause polymerisation. Only three mutations in SERPINC1 affecting two residues have been found to favour transformation to the latent conformation of antithrombin, another hyperstable non-anticoagulant form with strong antiangiogenic activity that constitutes 3 % of plasma antithrombin in healthy subjects. The analysis of latent antithrombin in 141 unrelated patients with antithrombin deficiency carrying 89 different SERPINC1 mutations identified four cases with higher levels than that of controls: p.Pro439Thr, p.Pro461Ser, p.Met283Val, and p.His401Tyr, the last also with circulating polymers. Heating of plasma at 42ºC exacerbated the transformation to the latent conformation in p.Pro439Thr and p.Pro461Ser. The conformational effect of p.Met283Val, the mutation associated with the highest levels of latent antithrombin detected in four members of a family, was verified in a recombinant model. Antithrombin deficiency in these cases should be classified as pleiotropic based on the impaired reactivity and low heparin affinity of the variant. Despite high levels of latent antithrombin (up to 80 µg/ml in p.Met283Val carriers), no vascular defects were described in carriers of these mutations. In conclusion, our study identifies new residues involved in the structural stability of antithrombin (and potentially of all serpins). High levels of endogenous latent antithrombin seem to play a minor antiangiogenic effect. Finally, pleiotropic deficiencies may be caused by mutations inducing transformation to the latent conformation.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Javier Corral
- Dr. Javier Corral, University of Murcia, Centro Regional de Hemodonación, Calle Ronda de Garay s/n. Murcia 30003, Spain, Tel.: +34 968341990, Fax: +34 968261914, E-mail:
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10
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Bourti Y, Saller F, Bianchini EP, Pautus S, Duong van Huyen JP, Marie AL, Tran NT, Molina TJ, Taverna M, Lerolle N, Borgel D. Antithrombin is not protective against renal ischaemia-reperfusion injury. Thromb Haemost 2017; 117:422-425. [PMID: 27786339 DOI: 10.1160/th16-06-0451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/06/2016] [Indexed: 11/05/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Delphine Borgel
- Delphine Borgel, INSERM UMR-S 1176, 80, rue du Général Leclerc, 94276 Le Kremlin-Bicêtre, France, Tel.: +33 1 49595646, Fax: +33 1 46719472, E-mail:
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11
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Trelle MB, Pedersen S, Østerlund EC, Madsen JB, Kristensen SR, Jørgensen TJD. An Asymmetric Runaway Domain Swap Antithrombin Dimer as a Key Intermediate for Polymerization Revealed by Hydrogen/Deuterium-Exchange Mass Spectrometry. Anal Chem 2016; 89:616-624. [PMID: 27783482 DOI: 10.1021/acs.analchem.6b02518] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Antithrombin deficiency is associated with increased risk of venous thrombosis. In certain families, this condition is caused by pathogenic polymerization of mutated antithrombin in the blood. To facilitate future development of pharmaceuticals against antithrombin polymerization, an improved understanding of the polymerogenic intermediates is crucial. However, X-ray crystallography of these intermediates is severely hampered by the difficulty in obtaining well-diffracting crystals of transient and heterogeneous noncovalent protein assemblies. Furthermore, their large size prohibits structural analysis by NMR spectroscopy. Here, we show how hydrogen/deuterium-exchange mass spectrometry (HDX-MS) provides detailed insight into the structural dynamics of each subunit in a polymerization-competent antithrombin dimer. Upon deuteration, this dimer surprisingly yields bimodal isotope distributions for the majority of peptides, demonstrating an asymmetric configuration of the two subunits. The data reveal that one subunit is very dynamic, potentially intrinsically disordered, whereas the other is considerably less dynamic. The local subunit-specific deuterium uptake of this polymerization-competent dimer strongly supports a β4A-β5A β-hairpin runaway domain swap mechanism for antithrombin polymerization. HDX-MS thus holds exceptional promise as an enabling analytical technique in the efforts toward future pharmacological intervention with protein polymerization and associated diseases.
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Affiliation(s)
- Morten Beck Trelle
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
| | - Shona Pedersen
- Department of Clinical Biochemistry, Aalborg University Hospital , Hobrovej 18, 9000 Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University , Sdr. Skovvej 15, 9000 Aalborg, Denmark
| | - Eva Christina Østerlund
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
| | - Jeppe Buur Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
| | - Søren Risom Kristensen
- Department of Clinical Biochemistry, Aalborg University Hospital , Hobrovej 18, 9000 Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University , Sdr. Skovvej 15, 9000 Aalborg, Denmark
| | - Thomas J D Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
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12
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Marie AL, Dominguez-Vega E, Saller F, Plantier JL, Urbain R, Borgel D, Tran NT, Somsen GW, Taverna M. Characterization of conformers and dimers of antithrombin by capillary electrophoresis-quadrupole-time-of-flight mass spectrometry. Anal Chim Acta 2016; 947:58-65. [PMID: 27846990 DOI: 10.1016/j.aca.2016.10.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/26/2016] [Accepted: 10/09/2016] [Indexed: 11/18/2022]
Abstract
Antithrombin (AT) is a plasma glycoprotein which possesses anticoagulant and anti-inflammatory properties. AT exhibits various forms, among which are native, latent and heterodimeric ones. We studied the potential of capillary electrophoresis-mass spectrometry (CE-MS) using a sheath liquid interface, electrospray ionization (ESI), and a quadrupole-time-of-flight (Q-TOF) mass spectrometer to separate and quantify the different AT forms. For CE separation, a neutral polyvinyl alcohol (PVA) coated capillary was employed. The protein conformation was preserved by using a background electrolyte (BGE) at physiological pH. A sheath liquid of isopropanol-water 50:50 (v/v) with 14 mM ammonium acetate delivered at a flow rate of 120 μL h-1 resulted in optimal signal intensities. Each AT form exhibited a specific mass spectrum, allowing unambiguous distinction. Several co-injection experiments proved that latent AT had a higher electrophoretic mobility (μep) than native AT, and that these conformers could associate to form a heterodimer during the CE analysis. The developed CE-MS method enabled the detection and quantitation of latent and heterodimeric forms in a commercial AT preparation stored at room temperature for three weeks.
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Affiliation(s)
- Anne-Lise Marie
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Univ. Paris-Sud, Université Paris-Saclay, 5 rue Jean-Baptiste Clément, 92290, Châtenay-Malabry, France
| | - Elena Dominguez-Vega
- Division of BioAnalytical Chemistry, AIMMS Research Group Biomolecular Analysis, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - François Saller
- Université Paris Sud, UMR-S1176, 94276, Le Kremlin-Bicêtre, France; INSERM, U1176, 94276, Le Kremlin-Bicêtre, France
| | | | | | - Delphine Borgel
- Université Paris Sud, UMR-S1176, 94276, Le Kremlin-Bicêtre, France; INSERM, U1176, 94276, Le Kremlin-Bicêtre, France; AP-HP, Hôpital Necker, Service d'Hématologie Biologique, 75015, Paris, France
| | - N Thuy Tran
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Univ. Paris-Sud, Université Paris-Saclay, 5 rue Jean-Baptiste Clément, 92290, Châtenay-Malabry, France
| | - Govert W Somsen
- Division of BioAnalytical Chemistry, AIMMS Research Group Biomolecular Analysis, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Myriam Taverna
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Univ. Paris-Sud, Université Paris-Saclay, 5 rue Jean-Baptiste Clément, 92290, Châtenay-Malabry, France.
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13
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Marie AL, Tran NT, Saller F, Abdou YM, Zeau P, Plantier JL, Urbain R, Borgel D, Taverna M. A capillary zone electrophoresis method to detect conformers and dimers of antithrombin in therapeutic preparations. Electrophoresis 2016; 37:1696-703. [DOI: 10.1002/elps.201500456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Anne-Lise Marie
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Université Paris-Sud; Université Paris-Saclay; Châtenay-Malabry France
| | - Nguyet Thuy Tran
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Université Paris-Sud; Université Paris-Saclay; Châtenay-Malabry France
| | - François Saller
- Université Paris Sud; UMR-S1176; Le Kremlin-Bicêtre France
- INSERM; U1176 Le Kremlin-Bicêtre France
| | - Youmna Mohamed Abdou
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Université Paris-Sud; Université Paris-Saclay; Châtenay-Malabry France
| | | | | | | | - Delphine Borgel
- Université Paris Sud; UMR-S1176; Le Kremlin-Bicêtre France
- INSERM; U1176 Le Kremlin-Bicêtre France
- AP-HP, Hôpital Necker; Service d'Hématologie Biologique; Paris France
| | - Myriam Taverna
- Institut Galien Paris Sud, UMR8612, Protein and Nanotechnology in Analytical Science (PNAS), CNRS, Université Paris-Sud; Université Paris-Saclay; Châtenay-Malabry France
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14
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Hotoleanu C. Genetic Risk Factors in Venous Thromboembolism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 906:253-272. [PMID: 27638626 DOI: 10.1007/5584_2016_120] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Genetic risk factors predispose to thrombophilia and play the most important etiopathogenic role in venous thromboembolism (VTE) in people younger than 50 years old. At least one inherited risk factor could be found in about half of the cases with a first episode of idiopathic VTE.Roughly, genetic risk factors are classified into two main categories: loss of function mutations (such as deficiencies of antithrombin, protein C, protein S) and gain of function mutations, (such as prothrombin mutation G20210A, factor V Leiden). A revolutionary contribution to the genetic background of VTE was brought by the achievements of the genome-wide association studies which analyze the association of a huge number of polymorphisms in large sample size.Hereditary thrombophilia testing should be done only in selected cases. The detection of hereditary thrombophilia has impact on the management of the anticoagulation in children with purpura fulminans, pregnant women at risk of VTE and may be useful in the assessment of the risk for recurrent thrombosis in patients presenting an episode of VTE at a young age (<40 years) and in cases with positive family history regarding thrombosis.
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Affiliation(s)
- Cristina Hotoleanu
- Department 5, Iuliu Hatieganu University of Medicine and Pharmacy, 8, Victor Babes street, 400012, Cluj-Napoca, Romania.
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A fast capillary electrophoresis method to assess the binding affinity of recombinant antithrombin toward heparin directly from cell culture supernatants. J Pharm Biomed Anal 2015; 111:64-70. [DOI: 10.1016/j.jpba.2015.02.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/13/2015] [Accepted: 02/20/2015] [Indexed: 11/19/2022]
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16
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Rousseau F, Schymkowitz J, Itzhaki LS. Implications of 3D domain swapping for protein folding, misfolding and function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 747:137-52. [PMID: 22949116 DOI: 10.1007/978-1-4614-3229-6_9] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Three-dimensional domain swapping is the process by which two identical protein chains exchange a part of their structure to form an intertwined dimer or higher-order oligomer. The phenomenon has been observed in the crystal structures of a range of different proteins. In this chapter we review the experiments that have been performed in order to understand the sequence and structural determinants of domain-swapping and these show how the general principles obtained can be used to engineer proteins to domain swap. We discuss the role of domain swapping in regulating protein function and as one possible mechanism of protein misfolding that can lead to aggregation and disease. We also review a number of interesting pathways of macromolecular assembly involving β-strand insertion or complementation that are related to the domain-swapping phenomenon.
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Affiliation(s)
- Frederic Rousseau
- VIB Switch Laboratory, Department of Molecular Cell Biology, Katholieke Universiteit Leuven, Leuven, Belgium
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17
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Olson ST, Gettins PGW. Regulation of proteases by protein inhibitors of the serpin superfamily. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 99:185-240. [PMID: 21238937 DOI: 10.1016/b978-0-12-385504-6.00005-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The serpins comprise an ancient superfamily of proteins, found abundantly in eukaryotes and even in some bacteria and archea, that have evolved to regulate proteases of both serine and cysteine mechanistic classes. Unlike the thermodynamically determined lock-and-key type inhibitors, such as those of the Kunitz and Kazal families, serpins use conformational change and consequent kinetic trapping of an enzyme intermediate to effect inhibition. By combining interactions of both an exposed reactive center loop and exosites outside this loop with the active site and complementary exosites on the target protease, serpins can achieve remarkable specificity. Together with the frequent use of regulatory cofactors, this permits a sophisticated time- and location-dependent mode of protease regulation. An understanding of the structure and function of serpins has suggested that they may provide novel scaffolds for engineering protease inhibitors of desired specificity for therapeutic use.
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Affiliation(s)
- Steven T Olson
- Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, Chicago, Illinois, USA
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18
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Pearce M, Powers G, Feil S, Hansen G, Parker M, Bottomley S. Identification and Characterization of a Misfolded Monomeric Serpin Formed at Physiological Temperature. J Mol Biol 2010; 403:459-67. [DOI: 10.1016/j.jmb.2010.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 08/10/2010] [Accepted: 09/02/2010] [Indexed: 11/26/2022]
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19
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Ordóñez A, Martínez-Martínez I, Corrales FJ, Miqueo C, Miñano A, Vicente V, Corral J. Effect of citrullination on the function and conformation of antithrombin. FEBS J 2009; 276:6763-72. [DOI: 10.1111/j.1742-4658.2009.07391.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Hernández-Espinosa D, Ordóñez A, Miñano A, Martínez-Martínez I, Vicente V, Corral J. Hyperglycaemia impairs antithrombin secretion: Possible contribution to the thrombotic risk of diabetes. Thromb Res 2009; 124:483-9. [DOI: 10.1016/j.thromres.2009.05.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 05/21/2009] [Accepted: 05/22/2009] [Indexed: 01/09/2023]
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21
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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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22
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Taher ZA, Brassard A. Venous leg ulcer in a 42-year-old woman: what should we think about? J Cutan Med Surg 2009; 13 Suppl 1:S20-5. [PMID: 19480747 DOI: 10.2310/7750.2009.00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Zaki A Taher
- Division of Dermatology and Cutaneous Sciences, Department of Medicine, University of Alberta, Edmonton, AB
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23
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Langdown J, Belzar KJ, Savory WJ, Baglin TP, Huntington JA. The Critical Role of Hinge-Region Expulsion in the Induced-Fit Heparin Binding Mechanism of Antithrombin. J Mol Biol 2009; 386:1278-89. [DOI: 10.1016/j.jmb.2009.01.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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24
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Schedin-Weiss S, Richard B, Hjelm R, Olson ST. Antiangiogenic forms of antithrombin specifically bind to the anticoagulant heparin sequence. Biochemistry 2009; 47:13610-9. [PMID: 19035835 DOI: 10.1021/bi801656u] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A specific pentasaccharide sequence of heparin binds with high affinity to native antithrombin and induces a conformational change in the inhibitor by a previously described two-step interaction mechanism. In this work, the interactions of heparin with the antiangiogenic latent and cleaved antithrombin forms were studied. Binding of heparin to these antithrombin forms was specific for the same pentasaccharide sequence as native antithrombin. Rapid kinetic studies demonstrated that this pentasaccharide induced a conformational change also in latent and cleaved antithrombin. The binding affinities of these antithrombin forms for the pentasaccharide, as compared to native antithrombin, were approximately 30-fold lower due to two to three fewer ionic interactions, resulting in less stable conformationally altered states. Affinities of latent and cleaved antithrombin for longer heparin chains, containing the pentasaccharide sequence, were 2-fold lower than for the pentasaccharide itself. This contrasts the interaction with native antithrombin and demonstrates that residues flanking the pentasaccharide sequence of heparin are repelled by the latent and cleaved forms. These findings contribute to delineating the mechanism by which heparin or heparan sulfate mediates antiangiogenic activity of antithrombin.
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Affiliation(s)
- Sophia Schedin-Weiss
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, SE-751 23 Uppsala, Sweden.
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25
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Carrell RW, Mushunje A, Zhou A. Serpins show structural basis for oligomer toxicity and amyloid ubiquity. FEBS Lett 2008; 582:2537-41. [PMID: 18573252 PMCID: PMC2568812 DOI: 10.1016/j.febslet.2008.06.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 06/02/2008] [Accepted: 06/05/2008] [Indexed: 11/15/2022]
Abstract
Many disorders, including Alzheimer’s, the prion encephalopathies and other neurodegenerative diseases, result from aberrant protein aggregation. Surprisingly, cellular toxicity is often due not to the highly-ordered aggregates but to the oligomers that precede their formation. Using serpins as a paradigm, we show how the active and infective interface of oligomers is inherently toxic and can promiscuously bind to unrelated peptides, including neurotransmitters. Extension of the oligomer and its eventual sequestration as amyloid can thus be seen as a protective response to block the toxic interface. We illustrate how the preferential self-association that gives this protection has been selectively favoured.
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Affiliation(s)
- Robin W Carrell
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.
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26
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Richard B, Swanson R, Schedin-Weiss S, Ramirez B, Izaguirre G, Gettins PGW, Olson ST. Characterization of the conformational alterations, reduced anticoagulant activity, and enhanced antiangiogenic activity of prelatent antithrombin. J Biol Chem 2008; 283:14417-29. [PMID: 18375953 PMCID: PMC2386924 DOI: 10.1074/jbc.m710327200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 03/20/2008] [Indexed: 11/06/2022] Open
Abstract
A conformationally altered prelatent form of antithrombin that possesses both anticoagulant and antiangiogenic activities is produced during the conversion of native to latent antithrombin (Larsson, H., Akerud, P., Nordling, K., Raub-Segall, E., Claesson-Welsh, L., and Björk, I. (2001) J. Biol. Chem. 276, 11996-12002). Here, we show that the previously characterized prelatent antithrombin is a mixture of native antithrombin and a modified, true prelatent antithrombin that are resolvable by heparin-agarose chromatography. Kinetic analyses revealed that prelatent antithrombin is an intermediate in the conversion of native to latent antithrombin whose formation is favored by stabilizing anions of the Hofmeister series. Purified prelatent antithrombin had reduced anticoagulant function compared with native antithrombin, due to a reduced heparin affinity and consequent impaired ability of heparin to either bridge prelatent antithrombin and coagulation proteases in a ternary complex or to induce full conformational activation of the serpin. Significantly, prelatent antithrombin possessed an antiangiogenic activity more potent than that of latent antithrombin, based on the relative abilities of the two forms to inhibit endothelial cell growth. The prelatent form was conformationally altered from native antithrombin as judged from an attenuation of tryptophan fluorescence changes following heparin activation and a reduced thermal stability. The alterations are consistent with the limited structural changes involving strand 1C observed in a prelatent form of plasminogen activator inhibitor-1 (Dupont, D. M., Blouse, G. E., Hansen, M., Mathiasen, L., Kjelgaard, S., Jensen, J. K., Christensen, A., Gils, A., Declerck, P. J., Andreasen, P. A., and Wind, T. (2006) J. Biol. Chem. 281, 36071-36081), since the (1)H NMR spectrum, electrophoretic mobility, and proteolytic susceptibility of prelatent antithrombin most resemble those of native rather than those of latent antithrombin. Together, these results demonstrate that limited conformational alterations of antithrombin that modestly reduce anticoagulant activity are sufficient to generate antiangiogenic activity.
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Affiliation(s)
- Benjamin Richard
- Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, Chicago, IL 60612, USA
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27
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Hernández-Espinosa D, Miñano A, Martínez C, Ordoñez A, Pérez-Ceballos E, de Arriba F, Mota RA, Ferrer F, González M, Vicente V, Corral J. Inhibition of proteasome by bortezomib causes intracellular aggregation of hepatic serpins and increases the latent circulating form of antithrombin. J Transl Med 2008; 88:306-17. [PMID: 18195690 DOI: 10.1038/labinvest.3700717] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Conformational diseases include heterogeneous disorders sharing a similar pathological mechanism, leading to intracellular aggregation of proteins with toxic effects. Serpins are commonly involved in these diseases. These are structurally sensitive molecules that modify their folding under even minor genetic or environmental variations. Indeed, under normal conditions, the rate of misfolding of serpins is high and unfolded serpins must be degraded by the proteasome system. Our aim was to study the effects of bortezomib, a proteasome inhibitor, on conformationally sensitive serpins. The effects of bortezomib were analysed in patients with multiple myeloma, HepG2 cells, and Swiss mice, as well as in vitro. Levels, anti-FXa activity, heparin affinity, and conformational features of antithrombin, a relevant anticoagulant serpin, were analysed. Histological, ultrastructural features and immunohistological distribution of antithrombin and alpha1-antitrypsin (another hepatic serpin) were evaluated. We also studied the intracellular accumulation of conformationally sensitive (fibrinogen) or non-sensitive (prothrombin) hepatic proteins. The inhibition of the proteasome caused intracellular accumulation and aggregation of serpins within the endoplasmic reticulum that was associated with confronting cisternae and Mallory body formation. These effects were accompanied by a heat stress response. Bortezomib also increased the levels of intracellular fibrinogen, but has no significant effect on prothrombin. Finally, bortezomib had only minor effects on the mature circulating antithrombin, with increased amounts of latent antithrombin in plasma. These results suggest that the impairment of proteasomal activities leads to an intracellular accumulation of conformationally sensitive proteins and might facilitate the release of misfolded serpins into circulation where they adopt more stable conformations.
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28
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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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29
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Dimers initiate and propagate serine protease inhibitor polymerisation. J Mol Biol 2007; 375:36-42. [PMID: 18005992 DOI: 10.1016/j.jmb.2007.10.055] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 10/18/2007] [Accepted: 10/19/2007] [Indexed: 02/06/2023]
Abstract
The serine protease inhibitor (serpin) family can readily form long-chain polymers by a process that underlies a variety of diseases. We show here that monomers of plasma serpins alpha(1)-antitrypsin and antithrombin are stable on incubation with the rate-limiting step in their polymerisation being the formation of the initial dimer. Once formed, the dimers readily interlink to form tetramers and can bind monomers to form trimers and longer oligomers. Cleavage of the only exposed reactive loop, in unit I of the dimers, prevents their interlinkage, but these cleaved dimers can still link to monomers. The rapid binding by the cleaved dimers of a peptide specific to the lower half of beta-sheet A of the molecule indicates the ready opening of this beta-sheet in unit II of the dimers. The failure of the cleaved dimers to bind peptide-complexed monomers, together with the relative inaccessibility of the P14 hinge residue in the oligomers, is evidence that partial insertion of the reactive loop into its own A-sheet is required for polymer formation. We propose that serpin dimers initiate and propagate polymerisation by having one exposed loop with an optimal conformation as a beta-strand donor and a readily opened beta-sheet as an acceptor. The sequential reformation of these activated beta-interfaces as the oligomer extends, molecule by molecule, provides a model for the fibril and amyloid formation of conformational diseases in general as well as for the infectivity of prion encephalopathies.
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Beinrohr L, Harmat V, Dobó J, Lörincz Z, Gál P, Závodszky P. C1 Inhibitor Serpin Domain Structure Reveals the Likely Mechanism of Heparin Potentiation and Conformational Disease. J Biol Chem 2007; 282:21100-9. [PMID: 17488724 DOI: 10.1074/jbc.m700841200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C1 inhibitor, a member of the serpin family, is a major down-regulator of inflammatory processes in blood. Genetic deficiency of C1 inhibitor results in hereditary angioedema, a dominantly inheritable, potentially lethal disease. Here we report the first crystal structure of the serpin domain of human C1 inhibitor, representing a previously unreported latent form, which explains functional consequences of several naturally occurring mutations, two of which are discussed in detail. The presented structure displays a novel conformation with a seven-stranded beta-sheet A. The unique conformation of the C-terminal six residues suggests its potential role as a barrier in the active-latent transition. On the basis of surface charge pattern, heparin affinity measurements, and docking of a heparin disaccharide, a heparin binding site is proposed in the contact area of the serpin-proteinase encounter complex. We show how polyanions change the activity of the C1 inhibitor by a novel "sandwich" mechanism, explaining earlier reaction kinetic and mutagenesis studies. These results may help to improve therapeutic C1 inhibitor preparations used in the treatment of hereditary angioedema, organ transplant rejection, and heart attack.
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Affiliation(s)
- László Beinrohr
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
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31
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Kjellberg M, Rimac B, Stenflo J. An immunochemical method for quantitative determination of latent antithrombin, the reactive center loop-inserted uncleaved form of antithrombin. J Thromb Haemost 2007; 5:127-32. [PMID: 17059411 DOI: 10.1111/j.1538-7836.2006.02274.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antithrombin (AT) is a serine protease inhibitor that has thrombin, factors IXa and Xa as target proteases. In addition to active native AT, two other forms have been identified in plasma: the reactive center loop inserted cleaved and latent, uncleaved forms. Both have been shown to be present in normal human blood. Latent AT forms a dimer with native AT in vitro, thus inactivating the native form. Here we describe a mouse monoclonal antibody, 8C8, that is specific for latent AT. The affinity of 8C8 was found to be 500-fold higher for latent than for native AT and 5000-fold higher for latent than for cleaved AT. A sandwich assay was developed to measure the concentration of latent AT in plasma, which was found to be approximately 4.8 mg L(-1) in healthy individuals. The K(D) of the interaction between native and latent AT was found to be 51 mum, i.e. far above the plasma concentration of both native and latent AT, indicating a negligible complex formation in blood.
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Affiliation(s)
- M Kjellberg
- Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital, Malmö, Sweden.
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32
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Zhang W, Swanson R, Xiong Y, Richard B, Olson ST. Antiangiogenic antithrombin blocks the heparan sulfate-dependent binding of proangiogenic growth factors to their endothelial cell receptors: evidence for differential binding of antiangiogenic and anticoagulant forms of antithrombin to proangiogenic heparan sulfate domains. J Biol Chem 2006; 281:37302-10. [PMID: 17040907 DOI: 10.1074/jbc.m604905200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The anticoagulant serpin antithrombin acquires a potent antiangiogenic activity upon undergoing conformational alterations to cleaved or latent forms. Here we show that antithrombin antiangiogenic activity is mediated at least in part through the ability of the conformationally altered serpin to block the proangiogenic growth factors fibroblast growth factor (FGF)-2 and vascular endothelial growth factor (VEGF) from forming signaling competent ternary complexes with their protein receptors and heparan sulfate co-receptors on endothelial cells. Cleaved and latent but not native forms of antithrombin blocked the formation of FGF-2-FGF receptor-1 ectodomain-heparin ternary complexes, and the dimerization of these complexes in solution and similarly inhibited the formation of FGF-2-heparin binary complexes and their dimerization. Only antiangiogenic forms of antithrombin likewise inhibited (125)I-FGF-2 binding to its low affinity heparan sulfate co-receptor and blocked FGF receptor-1 autophosphorylation and p42/44 MAP kinase phosphorylation in cultured human umbilical vein endothelial cells (HUVECs). Moreover, treatment of HUVECs with heparinase III to specifically eliminate the FGF-2 heparan sulfate co-receptor suppressed the ability of antiangiogenic antithrombin to inhibit growth factor-stimulated proliferation. Antiangiogenic antithrombin inhibited full-length VEGF(165) stimulation of HUVEC proliferation but did not affect the stimulation of cells by the heparin-binding domain-deleted VEGF(121). Taken together, these results demonstrate that antiangiogenic forms of antithrombin block the proangiogenic effects of FGF-2 and VEGF on endothelial cells by competing with the growth factors for binding the heparan sulfate co-receptor, which mediates growth factor-receptor interactions. Moreover, the inability of native antithrombin to bind this co-receptor implies that native and conformationally altered forms of antithrombin differentially bind proangiogenic heparan sulfate domains.
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Affiliation(s)
- Weiqing Zhang
- Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
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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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Hernández-Espinosa D, Miñano A, Martínez C, Pérez-Ceballos E, Heras I, Fuster JL, Vicente V, Corral J. L-asparaginase-induced antithrombin type I deficiency: implications for conformational diseases. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:142-53. [PMID: 16816368 PMCID: PMC1698772 DOI: 10.2353/ajpath.2006.051238] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serpinopathies, a group of diseases caused by mutations that disrupt the structurally sensitive serpins, have no known acquired cause. Interestingly, l-asparaginase treatment of acute lymphoblastic leukemia patients causes severe deficiency in the serpin antithrombin. We studied the consequences of this drug on antithrombin levels, activity, conformation, and immunohistological and ultrastructural features in plasma from acute lymphoblastic leukemia patients, HepG2 cells, and plasma and livers from mice treated with this drug. Additionally, we evaluated intracellular deposition of alpha1-antitrypsin. l-Asparaginase did not affect functional or conformational parameters of mature antithrombin; however, patients and mice displayed severe type I deficiency with no abnormal conformations of circulating antithrombin. Moreover, l-asparaginase impaired secretion of antithrombin by HepG2 cells. These effects were explained by the intracellular retention of antithrombin, forming aggregates within dilated endoplasmic reticulum cisterns. Similar effects were observed for alpha1-antitrypsin in plasma, cells, and livers, and intracellular aggregates of additional proteins were observed in frontal cortex and pancreas. This is the first report of a conformational drug-associated effect on serpins without genetic factors involved. l-Asparaginase treatment induces severe, acquired, and transient type I deficiency of antithrombin (and alpha1-antitrypsin) with intracellular accumulation of the nascent molecule, increasing the risk of thrombosis.
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Huntington JA. Shape-shifting serpins – advantages of a mobile mechanism. Trends Biochem Sci 2006; 31:427-35. [PMID: 16820297 DOI: 10.1016/j.tibs.2006.06.005] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 05/24/2006] [Accepted: 06/21/2006] [Indexed: 11/30/2022]
Abstract
Serpins use an extraordinary mechanism of protease inhibition that depends on a rapid and marked conformational change and causes destruction of the covalently linked protease. Serpins thus provide stoichiometric, irreversible inhibition, and their dependence on conformational change is exploited for signalling and clearance. The regulatory advantages provided by structural mobility are best illustrated by the heparin activation mechanisms of the plasma serpins antithrombin and heparin cofactor II. This mechanistic complexity, however, renders serpins highly susceptible to disease-causing mutations. Recent crystal structures reveal the intricate conformational rearrangements involved in protease inhibition, activity modulation and the unique molecular pathology of the remarkable shape-shifting serpins.
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Affiliation(s)
- James A Huntington
- University of Cambridge, Department of Haematology, Cambridge Institute for Medical Research, Division of Structural Medicine, Thrombosis Research Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK.
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36
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Hernández-Espinosa D, Ayala I, Castells MT, García-Pérez B, Martín-Castillo A, Miñano A, Arcas I, Vicente V, Corral J. Intracellular retention of hepatic serpins caused by severe hyperlipidemia. Liver Int 2006; 26:708-15. [PMID: 16842328 DOI: 10.1111/j.1478-3231.2006.01274.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND High levels of circulating lipids contribute to both the development of non-alcoholic liver steatosis (NALS) and peripheral arterial disease, leading to increased thrombotic risk. However, the effects of hyperlipidemia on hepatic proteins have barely been studied. Antithrombin is a hepatic serpin with anticoagulant and anti-inflammatory roles. The conformational flexibility of antithrombin renders it susceptible to both, genetic and posttranslational modifications. Thus, mutations and environmental factors have been shown to alter this molecule. METHODS We used a chick model to assess the effects of hyperlipidemic diets (HD) on this conformationally sensitive molecule. We determined antithrombin activity in plasma and evaluated the histological and immunohistological features of livers from these animals. RESULTS A HD for 6 months led to a significant intrahepatic retention and aggregation of antithrombin, which correlated with hepatic steatosis, as revealed by immunohistological analysis. Accordingly, a decrease in circulating antithrombin activity (48.71 +/- 6.35%) was observed. Other hepatic proteins, including heparin cofactor II, another anticoagulant serpin, also accumulated intracellularly. Atorvastatin and reversion to a normal diet after 3 months partially protected livers from these deleterious effects. CONCLUSIONS Our results support that hyperlipidemia-induced NALS causes a significant intracellular aggregation of hemostatic serpins in liver, which determines a decrease in their circulating levels.
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37
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Kjellberg M, Ikonomou T, Stenflo J. The cleaved and latent forms of antithrombin are normal constituents of blood plasma: a quantitative method to measure cleaved antithrombin. J Thromb Haemost 2006; 4:168-76. [PMID: 16409466 DOI: 10.1111/j.1538-7836.2005.01656.x] [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: 11/28/2022]
Abstract
Antithrombin (AT), a member of the serine protease inhibitor family, is the key regulator of thrombin activity in vivo. Thrombin inhibition is accomplished by the formation of covalent thrombin-AT (TAT) complex. The rate of inhibition is accelerated by heparin, which also leads to the formation of a substantial amount of cleaved AT. We produced a murine monoclonal antibody (mAb) (M9) that is specific for the two forms of AT, in which the reactive center loop is inserted into beta-sheet A, i.e. cleaved and latent AT. The antibody has no measurable affinity for native AT. Using M9 as a catcher antibody in conjunction with a mAb (M27) that does not bind latent AT, we developed a sandwich assay that measures cleaved AT without interference from latent and native AT. The concentration in healthy subjects was determined to be 1.3 mg L(-1) (range: 1.0-1.9), which was about 100-fold lower than the plasma concentration of native AT and 1000-fold higher than the concentration of the TAT complex. The cleaved AT concentration is higher than what would be expected from the rate of formation of cleaved AT in vitro in conjunction with TAT complex formation in the presence of heparin. The concentration of cleaved AT did not correlate with the TAT concentration in plasma from patients with venous thrombosis.
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Affiliation(s)
- M Kjellberg
- Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital, Malmö, Sweden.
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38
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Zhang W, Swanson R, Izaguirre G, Xiong Y, Lau LF, Olson ST. The heparin-binding site of antithrombin is crucial for antiangiogenic activity. Blood 2005; 106:1621-8. [PMID: 15905187 PMCID: PMC1895214 DOI: 10.1182/blood-2005-02-0547] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Accepted: 05/03/2005] [Indexed: 11/20/2022] Open
Abstract
The heparin-binding site of antithrombin is shown here to play a crucial role in mediating the antiangiogenic activity of conformationally altered cleaved and latent forms of the serpin. Blocking the heparin-binding site of cleaved or latent antithrombin by complexation with a high-affinity heparin pentasaccharide abolished the serpin's ability to inhibit proliferation, migration, capillary-like tube formation, basic fibroblast growth factor (bFGF) signaling, and perlecan gene expression in bFGF-stimulated human umbilical vein endothelial cells. Mutation of key heparin binding residues, when combined with modifications of Asn-linked carbohydrate chains near the heparin-binding site, also could abrogate the anti-proliferative activity of the cleaved serpin. Surprisingly, mutation of Lys114, which blocks anticoagulant activation of antithrombin by heparin, caused the native protein to acquire antiproliferative activity without the need for conformational change. Together, these results indicate that the heparin-binding site of antithrombin is of crucial importance for mediating the serpin's antiangiogenic activity and that heparin activation of native antithrombin constitutes an antiangiogenic switch that is responsible for turning off the antiangiogenic activity of the native serpin.
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Affiliation(s)
- Weiqing Zhang
- Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, Rm 530E, Dentistry (M/C 860), 801 S Paulina St, Chicago, IL 60612, USA
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39
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Onda M, Belorgey D, Sharp LK, Lomas DA. Latent S49P neuroserpin forms polymers in the dementia familial encephalopathy with neuroserpin inclusion bodies. J Biol Chem 2005; 280:13735-41. [PMID: 15664988 DOI: 10.1074/jbc.m413282200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serpinopathies result from conformational transitions in members of the serine proteinase inhibitor superfamily with aberrant tissue deposition or loss of function. They are typified by mutants of neuroserpin that are retained within the endoplasmic reticulum of neurons as ordered polymers in association with dementia. We show here that the S49P mutant of neuroserpin that causes the dementia familial encephalopathy with neuroserpin inclusion bodies (FENIB) forms a latent species in vitro and in vivo in addition to the formation of polymers. Latent neuroserpin is thermostable and inactive as a proteinase inhibitor, but activity can be restored by refolding. Strikingly, latent S49P neuroserpin is unlike any other latent serine proteinase inhibitor (serpin) in that it spontaneously forms polymers under physiological conditions. These data provide an alternative method for the inactivation of mutant neuroserpin as a proteinase inhibitor in FENIB and demonstrate a second pathway for the formation of intracellular polymers in association with disease.
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Affiliation(s)
- Maki Onda
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom.
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40
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Mushunje A, Evans G, Brennan SO, Carrell RW, Zhou A. Latent antithrombin and its detection, formation and turnover in the circulation. J Thromb Haemost 2004; 2:2170-7. [PMID: 15613023 DOI: 10.1111/j.1538-7836.2004.01047.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is now apparent that the inactivated latent and cleaved conformers of antithrombin (AT) are of pathological significance. Using a single-run electrophoretic technique that allows the quantitative assessment of these conformers in 2 microL plasma, we show that near 3% of the total AT in the circulations of normal individuals is in latent conformation. Only trace amounts of cleaved AT were observed. The slow decline in AT activity on incubation of plasma at 37 degrees C was shown to be almost wholly due to a transition of native AT to its inactive latent form. Also initial studies in the rabbit indicate that the latent form, like the cleaved, has an identical circulatory half-life to that of native AT. We deduce that the steady concentration of latent AT in the circulation is due to the transition of some 10(12) molecules of AT per second balanced by an equivalent clearance of the latent form. Examples of clinical applications of the new technique include its use as a comprehensive single-step screen for genetic variants associated with AT deficiency, and notably the potential it provides to monitor the changes responsible for the loss of AT in the shock syndromes.
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Affiliation(s)
- A Mushunje
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, UK
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41
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Corral J, Huntington JA, González-Conejero R, Mushunje A, Navarro M, Marco P, Vicente V, Carrell RW. Mutations in the shutter region of antithrombin result in formation of disulfide-linked dimers and severe venous thrombosis. J Thromb Haemost 2004; 2:931-9. [PMID: 15140129 DOI: 10.1111/j.1538-7836.2004.00749.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Missense mutations causing conformational alterations in serpins can be responsible for protein deficiency associated with human diseases. However, there are few data about conformational consequences of mutations affecting antithrombin, the main hemostatic serpin. OBJECTIVES To investigate the conformational and clinical effect of mutations affecting the shutter region of antithrombin. PATIENTS AND METHODS We identified two families with significant reduction of circulating antithrombin displaying early and severe venous thrombosis, frequently associated with pregnancy or infection. Mutations were determined by standard molecular methods. Biochemical studies were performed on plasma samples. One variant (P80S) was purified by heparin-affinity chromatography and gel filtration, and evaluated by proteomic analysis. Finally, we modelled the structure of the mutant dimer. RESULTS We identified two missense mutations affecting the shutter region of antithrombin: P80S and G424R. Carriers of both mutations presented traces of a similar abnormal antithrombin, supporting inefficiently expressed rather than non-expressed variants. The abnormal antithrombin purified from P80S carriers is an inactive disulfide-linked dimer of mutant antithrombin whose properties are consistent with head-to-head insertion of the reactive loop. CONCLUSIONS Our data support the conclusion that missense mutations affecting the shutter region of serpins have specific conformational effects resulting in the formation of mutant oligomers. The consequent inefficiency of secretion explains the accompanying deficiency and loss of function, but the severity of thrombosis associated with these mutations suggests that the oligomers also have new and undefined pathological properties that could be exacerbated by pregnancy or infection.
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Affiliation(s)
- J Corral
- Department of Medicine, University of Murcia, Murcia, Spain.
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42
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Johnson DJD, Huntington JA. The Influence of Hinge Region Residue Glu-381 on Antithrombin Allostery and Metastability. J Biol Chem 2004; 279:4913-21. [PMID: 14623882 DOI: 10.1074/jbc.m311644200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antithrombin becomes an efficient inhibitor of factor Xa and thrombin by binding a specific pentasaccharide sequence found on a small fraction of the heparan sulfate proteoglycans lining the microvaculature. In the structure of native antithrombin, the reactive center loop is restrained due to the insertion of its hinge region into the main beta-sheet A, whereas in the heparin-activated state the reactive center loop is freed from beta-sheet A. In both structures, hinge region residue Glu-381 makes several stabilizing contacts. To determine the role of these contacts in the allosteric mechanism of antithrombin activation, we replaced Glu-381 with an alanine. This variant is less active toward its target proteases than control antithrombin, due to a perturbation of the equilibrium between the two forms, and to an increase in stoichiometry of inhibition. Pentasaccharide binding affinity is reduced 4-fold due to an increase in the off-rate. These data suggest that the main role of Glu-381 is to stabilize the activated conformation. Stability studies also showed that the E381A variant is resistant to continued insertion of its reactive center loop upon incubation at 50 degrees C, suggesting new stabilizing interactions in the native structure. To test this hypothesis, and to aid in the interpretation of the kinetic data we solved to 2.6 A the structure of the variant. We conclude that wild-type Glu-381 interactions stabilize the activated state and decreases the energy barrier to full loop insertion.
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Affiliation(s)
- Daniel J D Johnson
- University of Cambridge, Department of Haematology, Cambridge Institute for Medical Research, Division of Structural Medicine, Thrombosis Research Unit, Wellcome Trust MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
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43
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Devlin GL, Carver JA, Bottomley SP. The Selective Inhibition of Serpin Aggregation by the Molecular Chaperone, α-Crystallin, Indicates a Nucleation-dependent Specificity. J Biol Chem 2003; 278:48644-50. [PMID: 14500715 DOI: 10.1074/jbc.m308376200] [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] [Indexed: 11/06/2022] Open
Abstract
Small heat shock proteins (sHsps) are a ubiquitous family of molecular chaperones that prevent the misfolding and aggregation of proteins. However, specific details about their substrate specificity and mechanism of chaperone action are lacking. alpha1-Antichymotrypsin (ACT) and alpha1-antitrypsin (alpha1-AT) are two closely related members of the serpin superfamily that aggregate through nucleation-dependent and nucleation-independent pathways, respectively. The sHsp alpha-crystallin was unable to prevent the nucleation-independent aggregation of alpha1-AT, whereas alpha-crystallin inhibited ACT aggregation in a dose-dependent manner. This selective inhibition of ACT aggregation coincided with the formation of a stable high molecular weight alpha-crystallin-ACT complex with a stoichiometry of 1 on a molar subunit basis. The kinetics of this interaction occur at the same rate as the loss of ACT monomer, suggesting that the monomeric species is bound by the chaperone. 4,4'-Dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (Bis-ANS) binding and far-UV circular dichroism data suggest that alpha-crystallin interacts specifically with a non-native conformation of ACT. The finding that alpha-crystallin does not interact with alpha1-AT under these conditions suggests that alpha-crystallin displays a specificity for proteins that aggregate through a nucleation-dependent pathway, implying that the dynamic nature of both the chaperone and its substrate protein is a crucial factor in the chaperone action of alpha-crystallin and other sHsps.
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Affiliation(s)
- Glyn L Devlin
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800
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44
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Corral J, Rivera J, Martínez C, González-Conejero R, Miñano A, Vicente V. Detection of conformational transformation of antithrombin in blood with crossed immunoelectrophoresis: new application for a classical method. ACTA ACUST UNITED AC 2003; 142:298-305. [PMID: 14647033 DOI: 10.1016/s0022-2143(03)00136-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The structural flexibility of antithrombin is essential for its molecular trapping mechanism but also makes it vulnerable to even minor changes affecting its conformational stability, which influences hemostasis significantly. The conformational transformation of this serpin has been poorly investigated in biologic samples because available immunologic methods hardly differentiate between different conformations of this protein. Crossed immunoelectrophoresis (CIE) in presence of heparin has been classically used to identify mutant antithrombins with low heparin affinity. We demonstrate that this method also separates native and relaxed antithrombin, permitting the analysis of conformational variations of this potent anticoagulant with just a few microliters of plasma. However, CIE does not distinguish between antithrombin conformations with reduced heparin affinity: latent, cleaved, thrombin-antithrombin complexes, or heparin-binding mutants. Therefore, clinical interpretation of CIE results should be examined with caution. Using this and other methods, and evaluating the functional activity of antithrombin, we analyzed the conformational transformation of antithrombin in biologic samples. We confirmed its transformation to the latent configuration by incubating it at 50 degrees C. This conformational change also occurs at 37 degrees C, supporting the idea that this process is involved in the senescence of antithrombin. However, fresh plasma contains only traces of latent antithrombin, suggesting that this conformation is rapidly cleared in vivo. Finally, small increases in temperature (to 40 degrees C) resulted in a faster conformational transformation of antithrombin. Fever has been suggested to have key structural, functional, and clinical consequences in patients with conformational mutations in antithrombin. Our results support a role for small changes in temperature in nonmutated antithrombin, suggesting that fever is a general risk factor for thrombosis.
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Affiliation(s)
- Javier Corral
- Hematology and Clinical Oncology Service, Department of Medicine, Hospital General Universitario, Centro Regional de Hemodonación, Universidad de Murcia, Spain
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45
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Zhang W, Chuang YJ, Swanson R, Li J, Seo K, Leung L, Lau LF, Olson ST. Antiangiogenic antithrombin down-regulates the expression of the proangiogenic heparan sulfate proteoglycan, perlecan, in endothelial cells. Blood 2003; 103:1185-91. [PMID: 14563633 DOI: 10.1182/blood-2003-08-2920] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Antithrombin, a key serpin family regulator of blood coagulation proteases, is transformed into a potent antiangiogenic factor by limited proteolysis or mild heating. Here, we show by cDNA microarray, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), Northern blotting, and immunoblotting analyses that the expression of the proangiogenic heparan sulfate proteoglycan (HSPG), perlecan, but not other HSPGs, is dramatically down-regulated in human umbilical vein endothelial cells (HUVECs) treated with antiangiogenic cleaved and latent forms of antithrombin but not with the native form. Down-regulation of perlecan expression by cleaved and latent antithrombins was observed in both basic fibroblast growth factor (bFGF)-stimulated and unstimulated cells, whereas the antiangiogenic antithrombins inhibited the proliferation of only bFGF-stimulated HUVECs by arresting cells at the G(1) cell cycle phase. The importance of perlecan expression levels in mediating the antiproliferative effect of the antiangiogenic antithrombins was suggested by the finding that transforming growth factor-beta 1, a potent stimulator of perlecan expression in endothelial cells, blocked the down-regulation of perlecan expression and antiproliferative activity of cleaved antithrombin on endothelial cells. The previously established key role of perlecan in mediating bFGF stimulation of endothelial cell proliferation and angiogenesis suggests that a primary mechanism by which antiangiogenic antithrombins exert their effects is through the down-regulation of perlecan expression.
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Affiliation(s)
- Weiqing Zhang
- Center for Molecular Biology of Oral Diseases and Department of Biochemistry and Molecualr Genetics, University of Illinois at Chicago, 60612, USA
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46
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Long GL, Kjellberg M, Villoutreix BO, Stenflo J. Probing plasma clearance of the thrombin-antithrombin complex with a monoclonal antibody against the putative serpin-enzyme complex receptor-binding site. ACTA ACUST UNITED AC 2003; 270:4059-69. [PMID: 14519117 DOI: 10.1046/j.1432-1033.2003.03793.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A high-affinity monoclonal antibody (M27), raised against the human thrombin-antithrombin complex, has been identified and characterized. The epitope recognized by M27 was located to the linear sequence FIREVP (residues 411-416), located in the C-terminal cleavage peptide of antithrombin. This region overlaps, by two residues, the putative binding site of antithrombin for the serpin-enzyme complex receptor. Studies in rats and with HepG2 cells in culture indicated that the Fab fragment of M27 does not block binding and uptake of the thrombin-antithrombin complex, suggesting that this region does not play a major role in the recognition and clearance of the thrombin-antithrombin complex. M27 blocked the ability of antithrombin to inhibit thrombin as well as antithrombin cleavage, both in the presence and absence of heparin.
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Affiliation(s)
- George L Long
- Department of Biochemistry, University of Vermont, Burlington, VT, USA
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47
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Johnson DJD, Huntington JA. Crystal structure of antithrombin in a heparin-bound intermediate state. Biochemistry 2003; 42:8712-9. [PMID: 12873131 DOI: 10.1021/bi034524y] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Antithrombin is activated as an inhibitor of the coagulation proteases through its specific interaction with a heparin pentasaccharide. The binding of heparin induces a global conformational change in antithrombin which results in the freeing of its reactive center loop for interaction with target proteases and a 1000-fold increase in heparin affinity. The allosteric mechanism by which the properties of antithrombin are altered by its interactions with the specific pentasaccharide sequence of heparin is of great interest to the medical and protein biochemistry communities. Heparin binding has previously been characterized as a two-step, three-state mechanism where, after an initial weak interaction, antithrombin undergoes a conformational change to its high-affinity state. Although the native and heparin-activated states have been determined through protein crystallography, the number and magnitude of conformational changes render problematic the task of determining which account for the improved heparin affinity and how the heparin binding region is linked to the expulsion of the reactive center loop. Here we present the structure of an intermediate pentasaccharide-bound conformation of antithrombin which has undergone all of the conformational changes associated with activation except loop expulsion and helix D elongation. We conclude that the basis of the high-affinity state is not improved interaction with the pentasaccharide but a lowering of the global free energy due to conformational changes elsewhere in antithrombin. We suggest a mechanism in which the role of helix D elongation is to lock antithrombin in the five-stranded fully activated conformation.
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Affiliation(s)
- Daniel J D Johnson
- Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
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48
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Abstract
Serpins are the predominant protease inhibitors in the higher organisms and are responsible, in humans, for the control of many highly regulated processes including blood coagulation and fibrinolysis. The serpin inhibitory mechanism has recently been revealed by the solution of a crystallographic structure of the final serpin-protease complex. The serpin mechanism, in contrast to the classical lock-and-key mechanism, involves dramatic conformational change in both the inhibitor and the inhibited protein. The final result is a stable covalent complex in which the properties of each component are altered so as to allow clearance from the circulation. Several serpins are involved in hemostasis: antithrombin (AT) inhibits many coagulation proteases, most importantly factor Xa and thrombin; heparin cofactor II (HCII) inhibits thrombin; protein C inhibitor (PCI) inhibits activated protein C and thrombin bound to thrombomodulin; plasminogen activator inhibitor 1 inhibits tissue plasminogen activator; and alpha2-antiplasmin inhibits plasmin. Nearly all of these reactions are accelerated through interactions with glycosaminoglycans (GAGs) such as heparin or heparan sulfate. Recent structures of AT, HCII and PCI have revealed how in each case the serpin mechanism has been fine-tuned by evolution to bring about high levels of regulatory control, and how seemingly disparate mechanisms of GAG binding and activation can share critical elements. By considering the serpins involved in hemostasis together it is possible to develop a deeper understanding of their complex individual roles.
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Affiliation(s)
- J A Huntington
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, UK.
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49
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Zhou A, Stein PE, Huntington JA, Carrell RW. Serpin polymerization is prevented by a hydrogen bond network that is centered on his-334 and stabilized by glycerol. J Biol Chem 2003; 278:15116-22. [PMID: 12578831 DOI: 10.1074/jbc.m211663200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polymerization of serpins commonly results from mutations in the shutter region underlying the bifurcation of strands 3 and 5 of the A-sheet, with entry beyond this point being barred by a H-bond network centered on His-334. Exposure of this histidine in antithrombin, which has a partially opened sheet, allows polymerization and peptide insertion to occur at pH 6 or less when His-334 will be predictably protonated with disruption of the H-bond network. Similarly, thermal stability of antithrombin is pH-dependent with a single unfolding transition at pH 6, but there is no such transition when His-334 is buried by a fully closed A-sheet in heparin-complexed antithrombin or in alpha(1)-antitrypsin. Replacement of His-334 in alpha(1)-antitrypsin by a serine or alanine at pH 7.4 results in the same polymerization and loop-peptide acceptance observed with antithrombin at low pH. The critical role of His-334 and the re-formation of its H-bond network by the conserved P8 threonine, on the full insertion of strand 4, are relevant for the design of therapeutic blocking agents. This is highlighted here by the crystallographic demonstration that glycerol, which at high concentrations blocks polymerization, can replace the P8 threonine and re-form the disrupted H-bond network with His-334.
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Affiliation(s)
- Aiwu Zhou
- Department of Haematology, University of Cambridge, Cambridge Institute of Medical Research, Hills Road, Cambridge CB2 2XY, United Kingdom.
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50
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Karlsson G, Winge S. Separation between the alpha and beta forms of human antithrombin by hydroxyapatite high-performance liquid chromatography. Protein Expr Purif 2003; 28:196-201. [PMID: 12651125 DOI: 10.1016/s1046-5928(02)00678-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human antithrombin (AT) inhibits several proteases in the coagulation system, including thrombin and factor Xa, and thus, plays an important role in the regulation of blood coagulation. The predominant form of AT in plasma is ATalpha, which contains four glycosylated asparagine residues, and the minor form is ATbeta, which lacks the Asn-135 glycosylation. In this study, hydroxyapatite high-performance liquid chromatography, using a segmented sodium phosphate gradient, was utilized for the high-resolution separation of ATalpha and ATbeta. The detection limit (signal-to-noise ratio of 3) for ATbeta was 30 microg/mL, corresponding to 0.5% of the injected concentration of AT. Two analyzed commercial AT products both contained about 2% ATbeta. This method is suitable for the determination of ATbeta in pure samples of native AT.
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Affiliation(s)
- Göran Karlsson
- Plasma R & D, Octapharma AB, SE-11275 Stockholm, Sweden.
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