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Balogh G, Bereczky Z. Molecular Mechanisms of the Impaired Heparin Pentasaccharide Interactions in 10 Antithrombin Heparin Binding Site Mutants Revealed by Enhanced Sampling Molecular Dynamics. Biomolecules 2024; 14:657. [PMID: 38927061 PMCID: PMC11201378 DOI: 10.3390/biom14060657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/27/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
Antithrombin (AT) is a critical regulator of the coagulation cascade by inhibiting multiple coagulation factors including thrombin and FXa. Binding of heparinoids to this serpin enhances the inhibition considerably. Mutations located in the heparin binding site of AT result in thrombophilia in affected individuals. Our aim was to study 10 antithrombin mutations known to affect their heparin binding in a heparin pentasaccharide bound state using two molecular dynamics (MD) based methods providing enhanced sampling, GaMD and LiGaMD2. The latter provides an additional boost to the ligand and the most important binding site residues. From our GaMD simulations we were able to identify four variants (three affecting amino acid Arg47 and one affecting Lys114) that have a particularly large effect on binding. The additional acceleration provided by LiGaMD2 allowed us to study the consequences of several other mutants including those affecting Arg13 and Arg129. We were able to identify several conformational types by cluster analysis. Analysis of the simulation trajectories revealed the causes of the impaired pentasaccharide binding including pentasaccharide subunit conformational changes and altered allosteric pathways in the AT protein. Our results provide insights into the effects of AT mutations interfering with heparin binding at an atomic level and can facilitate the design or interpretation of in vitro experiments.
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Affiliation(s)
- Gábor Balogh
- Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Zsuzsanna Bereczky
- Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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Bravo‐Pérez C, Morena‐Barrio ME, Morena‐Barrio B, Miñano A, Padilla J, Cifuentes R, Garrido P, Vicente V, Corral J. Molecular and clinical characterization of transient antithrombin deficiency: A new concept in congenital thrombophilia. Am J Hematol 2022; 97:216-225. [PMID: 34800304 DOI: 10.1002/ajh.26413] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/13/2021] [Accepted: 11/16/2021] [Indexed: 11/07/2022]
Abstract
Antithrombin deficiency, the most severe thrombophilia, might be underestimated, since it is only investigated in cases with consistent functional deficiency or family history. We have analyzed 444 consecutive, unrelated cases, from 1998 to 2021, with functional results supporting antithrombin deficiency in at least one sample. Plasma antithrombin was evaluated by functional and biochemical methods in at least two samples. SERPINC1 gene was analyzed by sequencing and MPLA. Hypoglycosylation was studied by electrophoresis and high-performance liquid chromatography (HPLC). In 260 of 305 cases (85.2%) with constitutive deficiency (activity < 80% in all samples), a SERPINC1 (N = 250), or N-glycosylation defect (N = 10) was observed, while 45 remained undetermined. The other 139 cases had normal antithrombin activity (≥ 80%) in at least one sample, what we called transient deficiency. Sixty-one of these cases (43.9%) had molecular defects: 48 had SERPINC1 variants, with two recurrent mutations (p.Ala416Ser[Cambridge II], N = 15; p.Val30Glu[Dublin], N = 12), and 13 hypoglycosylation. Thrombotic complications occurred in transient deficiency, but were less frequent, latter-onset, and had a higher proportion of arterial events than in constitutive deficiency. Two mechanisms explained transient deficiency: The limitation of functional methods to detect some variants and the influence of external factors on the pathogenic consequences of these mutations. Our study reveals a molecular defect in a significant proportion of cases with transient antithrombin deficiency, and changes the paradigm of thrombophilia, as the pathogenic effect of some mutations might depend on external factors and be present only at certain timepoints. Antithrombin deficiency is underestimated, and molecular screening might be appropriate in cases with fluctuating laboratory findings.
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Affiliation(s)
- Carlos Bravo‐Pérez
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - María Eugenia Morena‐Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Belén Morena‐Barrio
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Antonia Miñano
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - José Padilla
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Rosa Cifuentes
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Pedro Garrido
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Vicente Vicente
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
| | - Javier Corral
- Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, IMIB, CIBERER Universidad de Murcia Murcia Spain
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Kruijt M, van der Pol LM, Eikenboom J, Verburg HJ, Cobbaert CM, Ruhaak LR. Unraveling a borderline antithrombin deficiency case with quantitative mass spectrometry. J Thromb Haemost 2022; 20:145-148. [PMID: 34653293 PMCID: PMC9298056 DOI: 10.1111/jth.15553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/27/2022]
Abstract
Antithrombin deficiency diagnostics by first-line activity tests suffer from a lack of sensitivity sometimes resulting in diagnostic uncertainty. We here present a case of a woman with recurrent pregnancy loss who was screened for inherited thrombophilia. Antithrombin activity was borderline low, resulting in uncertainty about the correct diagnosis. Using a mass spectrometry-based test, the antithrombin protein of the patient was characterized at the molecular level and a heterozygous p.Pro73Leu mutation was identified. The mutation, also known as antithrombin "Basel," increases the risk of venous thromboembolism and obstetric complications. This case is illustrative of current antithrombin deficiency screening, in which diagnoses may be missed by traditional diagnostics. Next-generation protein diagnostics by mass spectrometry provides molecular insight into the proteoforms present in vivo. This information is essential for laboratory specialists and clinicians to unambiguously diagnose patients and will aid in evolving healthcare from traditional to precision diagnostics.
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Affiliation(s)
- Mirjam Kruijt
- Department of Clinical Chemistry and Laboratory MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - Liselotte M. van der Pol
- Department of Internal MedicineDivision of Thrombosis and HemostasisLeiden University Medical CenterLeidenThe Netherlands
| | - Jeroen Eikenboom
- Department of Internal MedicineDivision of Thrombosis and HemostasisLeiden University Medical CenterLeidenThe Netherlands
| | - Harjo J. Verburg
- Department of Gynecology and FertilityLeiden University Medical CenterLeidenThe Netherlands
| | - Christa M. Cobbaert
- Department of Clinical Chemistry and Laboratory MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - L. Renee Ruhaak
- Department of Clinical Chemistry and Laboratory MedicineLeiden University Medical CenterLeidenThe Netherlands
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Investigation of the Differences in Antithrombin to Heparin Binding among Antithrombin Budapest 3, Basel, and Padua Mutations by Biochemical and In Silico Methods. Biomolecules 2021; 11:biom11040544. [PMID: 33917853 PMCID: PMC8068293 DOI: 10.3390/biom11040544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/31/2021] [Accepted: 04/06/2021] [Indexed: 11/16/2022] Open
Abstract
Antithrombin (AT) is a serine protease inhibitor, its activity is highly accelerated by heparin. Mutations at the heparin-binding region lead to functional defect, type II heparin-binding site (IIHBS) AT deficiency. The aim of this study was to investigate and compare the molecular background of AT Budapest 3 (p.Leu131Phe, ATBp3), AT Basel (p.Pro73Leu), and AT Padua (p.Arg79His) mutations. Advanced in silico methods and heparin-binding studies of recombinant AT proteins using surface plasmon resonance method were used. Crossed immunoelectrophoresis and Differential Scanning Fluorimetry (NanoDSF) were performed in plasma samples. Heparin affinity of AT Padua was the lowest (KD = 1.08 × 10-6 M) and had the most severe consequences affecting the allosteric pathways of activation, moreover significant destabilizing effects on AT were also observed. KD values for AT Basel, ATBp3 and wild-type AT were 7.64 × 10-7 M, 2.15 × 10-8 M and 6.4 × 10-10 M, respectively. Heparin-binding of AT Basel was slower, however once the complex was formed the mutation had only minor effect on the secondary and tertiary structures. Allosteric activation of ATBp3 was altered, moreover decreased thermostability in ATBp3 homozygous plasma and increased fluctuations in multiple regions of ATBp3 were observed by in silico methods suggesting the presence of a quantitative component in the pathogenicity of this mutation due to molecular instability.
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Maruyama K, Kokame K. Carrier frequencies of antithrombin, protein C, and protein S deficiency variants estimated using a public database and expression experiments. Res Pract Thromb Haemost 2021; 5:179-186. [PMID: 33537542 PMCID: PMC7845069 DOI: 10.1002/rth2.12456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/30/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Genetic deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are risk factors for venous thromboembolism. In the general population, the prevalence of heterozygous deficiency of AT, PC, and PS are reported as approximately 0.02%-0.2%, 0.2%-0.4%, and 0.03%-0.5%, respectively. The Exome Aggregation Consortium (ExAC) provides a public database containing reference data for over 60 000 exomes. OBJECTIVE This study aimed to determine the frequency of AT, PC, and PS deficiencies using the ExAC database and transient expression experiments. METHODS In total, 133, 157, and 221 variants of SERPIN1 (encoding AT), PROC (PC), and PROS1 (PS), respectively, were registered as missense and putative loss-of-function variants in the ExAC database. Variants with relatively high allele frequencies were selected and randomly sampled. Recombinant proteins were expressed in human embryo kidney 293 cells and their secretion and anticoagulant activities examined. RESULTS AND CONCLUSION We assessed 9 AT, 4 PC, and 14 PS variants with relatively high allele frequencies and randomly sampled 12 AT, 15 PC, and 19 PS missense variants. All 21 AT variants showed normal or mildly reduced secretion, and 6 showed reduced total activity (specific activity × antigen level). Of the 19 PC variants, 11 showed impaired total activity. All 33 PS variants showed normal or mildly reduced secretion, and 4 showed reduced total activity. Based on allele frequencies in the ExAC database, we calculated the frequencies of AT, PC, and PS genetic deficiency as 0.36%, 0.63%, and 0.39%, respectively.
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Affiliation(s)
- Keiko Maruyama
- Department of Molecular PathogenesisNational Cerebral and Cardiovascular CenterSuitaJapan
| | - Koichi Kokame
- Department of Molecular PathogenesisNational Cerebral and Cardiovascular CenterSuitaJapan
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6
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Seventeen novel SERPINC1 variants causing hereditary antithrombin deficiency in a Czech population. Thromb Res 2020; 189:39-41. [PMID: 32151802 DOI: 10.1016/j.thromres.2020.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 02/07/2020] [Accepted: 02/29/2020] [Indexed: 11/23/2022]
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Bravo-Pérez C, Vicente V, Corral J. Management of antithrombin deficiency: an update for clinicians. Expert Rev Hematol 2019; 12:397-405. [PMID: 31116611 DOI: 10.1080/17474086.2019.1611424] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Introduction. Antithrombin is a serpin that inhibits multiple procoagulant serine proteases and acts as an endogenous anticoagulant. Thus, congenital antithrombin deficiency constitutes a major thrombophilic state, the most severe so far. Areas covered. In the present work, we globally review the biology, genetics, diagnosis, and management of congenital antithrombin deficiency, and also discuss puzzling questions and future perspectives regarding this severe inherited thrombophilia. Expert opinion. Although this disorder exerts high clinical heterogeneity, many carriers will need careful and long-term anticoagulation and/or thromboprophylaxis, especially in high-risk situations, such as surgery and pregnancy. Notably, antithrombin concentrates constitute a considerable arsenal for both treatment and prevention of acute venous thrombosis in subjects with antithrombin deficiency. Current evidences are based almost exclusively on retrospective case series, so an integrated functional, biochemical and molecular characterization will be of clinical relevance and guide hematologists' personalized decisions.
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Affiliation(s)
- Carlos Bravo-Pérez
- a Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación , Universidad de Murcia, IMIB-Arrixaca, CIBERER , Murcia , Spain
| | - Vicente Vicente
- a Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación , Universidad de Murcia, IMIB-Arrixaca, CIBERER , Murcia , Spain
| | - Javier Corral
- a Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación , Universidad de Murcia, IMIB-Arrixaca, CIBERER , Murcia , Spain
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Amiral J, Seghatchian J. Revisiting antithrombin in health and disease, congenital deficiencies and genetic variants, and laboratory studies on α and β forms. Transfus Apher Sci 2018; 57:291-297. [PMID: 29784539 DOI: 10.1016/j.transci.2018.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Antithrombin [AT] is the main inhibitor for activated plasma coagulation serine esterases, inhibiting thrombin, Factors Xa and IXa, but also Factors XIIa, XIa, VIIa, kallicrein, and plasmin. Its activity is highly enhanced by heparin, through binding to the pentasaccharide sequences, for inhibition of all coagulation proteases, except thrombin, which inhibition requires its additional binding to the heparin polysaccharide chain. However, AT is the major inhibitor of thrombin in the blood circulation. Congenital or acquired deficiencies of AT expose affected patients to an increased risk of developing unprovoked and recurrent thrombo-embolic diseases. Antithrombin can be measured with various laboratory techniques, by either immunological or functional methods. Earlier, a radial immunodiffusion immunoassay allowed measurement of the protein antigenic content. Functional assays are mainly designed with Anti-Thrombin or Anti-Factor Xa chromogenic methods and are useful for detecting genetic molecular mutations with decreased inhibitory activity and contributed to study the conformational changes of antithrombin and its variants, which potentially regulate the activity of this serine protease inhibitor. These assays are not equivalent in terms of diagnosing protein abnormalities, associated with increased thrombotic incidence, and they have variable performance for reflecting impaired antithrombin binding capacity for heparin, reduced progressive inhibition of serine proteases, or accelerated switch rates to the latent and less active forms. A small proportion of AT (<10%) is present in blood in the β-form, with a lower oligosaccharide content, a lower Molecular Weight, a higher binding rate to endothelial glycosaminoglycans, and a higher anticoagulant activity, hence requiring specific laboratory methods for its measurement. The β-AT form is then of critical importance for controlling blood activation by tissue injury and preventing development of thrombo-embolic diseases. This article reviews the performance characteristics of the currently available assays, and their usefulness for monitoring the use of AT concentrates in intensive care units, disseminated intravascular coagulation or severe infections, to restore the anticoagulant protective effect of heparin by supplementing the requested AT concentration. The issues of automation, harmonization and standardization are also revisited and discussed.
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Affiliation(s)
- Jean Amiral
- SH-Consulting, Andrésy, France; Scientific and Technical Advisor for Hyphen BioMed, Sysmex group, Neuville sur Oise, France.
| | - Jerard Seghatchian
- International Consultancy in Blood Components Quality/Safety Improvement, Audit/Inspection and DDR Strategies, London, UK.
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Li YQ, Guo T, Wang QY, Liu H, Wu YY, Cheng ZP, Hu B, Lu X, Yu JM, Deng J, Wang HF, Sun CY, Yang Y, Zeng W, Tang L, Jian XR, Hu Y. Genetic analysis should be included in clinical practice when screening for antithrombin deficiency. Thromb Haemost 2017; 113:262-71. [DOI: 10.1160/th14-05-0446] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 08/30/2014] [Indexed: 12/12/2022]
Abstract
SummaryAntithrombin (AT) deficiency increases the risk of thrombosis. Current evidence shows that some SERPINC1 mutations responsible for antithrombin deficiency often present a slightly decreased or normal activity and therefore could not be detected by functional tests. This study was designed to compare activity assays and direct genetic analyses in identifying hereditary antithrombin deficiency. In total, 400 consecutive patients with venous thrombosis were enrolled. Functional assays showed that 16 of the 400 individuals had decreased antithrombin activity, and 14 of them were confirmed by genetic analysis. Of the remaining 384 patients, 95 individuals without a known risk factor and 95 individuals with predisposing factors were also selected for gene sequencing. Eight additional causative mutations were identified in nine individuals and they should also be considered as antithrombin deficiency. In addition, a recurrent mutation, p.Arg356_Phe361del, was characterised. The mutant appeared to have a partially impaired secretion and a reduction in functional activity by 50 %. This study indicated that including genetic analysis in screening tests for identifying antithrombin deficiency was essential. Specifically, a genetic analysis of SERPINC1 is strongly recommended when individuals experience unprovoked thrombotic diseases, even if the AT activities are normal.
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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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Moore GW, de Jager N, Cutler JA. Development of a novel, rapid assay for detection of heparin-binding defect antithrombin deficiencies: the heparin-antithrombin binding (HAB) ratio. Thromb Res 2015; 135:161-6. [DOI: 10.1016/j.thromres.2014.10.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 09/25/2014] [Accepted: 10/27/2014] [Indexed: 10/24/2022]
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Aguila S, Navarro-Fernández J, Bohdan N, Gutiérrez-Gallego R, de la Morena-Barrio ME, Vicente V, Corral J, Martínez-Martínez I. Role of the C-sheet in the maturation of N-glycans on antithrombin: functional relevance of pleiotropic mutations. J Thromb Haemost 2014; 12:1131-40. [PMID: 24824609 DOI: 10.1111/jth.12606] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 04/15/2014] [Indexed: 12/01/2022]
Abstract
BACKGROUND The characterization of natural mutants identified in patients with antithrombin deficiency has helped to identify functional domains or regions of this key anticoagulant and the mechanisms involved in the deficiency, as well as to define the clinical prognosis. Recently, we described an abnormal glycosylation in a pleiotropic mutant (K241E) that explained the impaired heparin affinity and the mild risk of thrombosis in carriers. OBJECTIVES To evaluate the effects of different natural pleiotropic mutations on the glycosylation of antithrombin and their functional effects. METHODS Five pleiotropic mutations identified in patients with antithrombin deficiency and located at each one of the strands of the C-sheet were selected (K241E, M251I, M315K, F402L, and P429L). Recombinant mutants were generated and purified. Glycoform heterogeneity and conformational sensitivity were studied with electrophoresis, proteomic analysis, and glycomic analysis. Heparin affinity was evaluated from intrinsic fluorescence. Reactivity assays with factor Xa, thrombin and neutrophil elastase in the presence or absence of heparin were also performed. RESULTS AND CONCLUSIONS Pleiotropic mutants, except for that with the M315K mutation, which affects a non-exposed residue, showed two glycoforms. Variant 1, with abnormal glycosylation, had reduced heparin affinity and severely affected reactivity with the target proteases. In contrast, variant 2, with similar electrophoretic mobility and heparin affinity to wild-type antithrombin, had impaired inhibitory activity that was partially compensated for by activation with heparin. Our results suggest the C-sheet of antithrombin as a new region that is relevant for proper maturation of the N-glycans. Therefore, pleiotropic mutations lead to glycosylation defects that are responsible for the reduced heparin affinity.
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Affiliation(s)
- S Aguila
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica HU Morales Meseguer, University of Murcia, IMIB, Murcia, Spain
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Abstract
Pediatric thrombosis and thrombophilia are increasingly recognized and studied. In this article, both the inherited and acquired factors for the development of thrombosis in neonates and children are categorized using the elements of Virchow's triad: stasis, hypercoagulable state, and vascular injury. The indications and rationale for performing thrombophilia testing are described. Also included are discussions on who, how, when, and why to test. Finally, recommendations for the use of contraceptives for adolescent females with a family history of thrombosis are outlined.
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Affiliation(s)
- Janet Y K Yang
- Division of Hematology and Oncology, Department of Pediatrics, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
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14
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Puurunen M, Salo P, Engelbarth S, Javela K, Perola M. Type II antithrombin deficiency caused by a founder mutation Pro73Leu in the Finnish population: clinical picture. J Thromb Haemost 2013; 11:1844-9. [PMID: 23910795 DOI: 10.1111/jth.12364] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/11/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND It has been shown that some antithrombin (AT) activity assays do not correctly detect inherited type II AT deficiency, but erroneously classify these patients as normal. OBJECTIVES Our aim was to investigate the mutations causing type II AT deficiency and to correlate the AT activity results with the genetic findings. PATIENTS/METHODS A large population (n = 104; 42 families) of Finnish patients with known AT type II deficiency were interviewed for clinical data. Their AT activity was measured with five commercially available methods, and the SERPINC1 gene was genotyped. RESULTS The mutations detected in type II AT-deficient patients were as follows: p.Pro73Leu (AT Basel) in 37 of 42 (88.1%) families; and p.Val30Glu, p.Arg425Cys and p.Pro439Ala in one family each. In two families, no mutation was detected. In the carriers of AT Basel two AT activity assays correctly identified most of the patients as AT-deficient, whereas three assays misclassified almost all of these patients as normal. Carriers of the founder mutation had, in addition to an elevated risk of venous thrombosis, a high risk of arterial thrombosis at young age, especially stroke. CONCLUSION In Finland, a population with a strong founder effect, AT type II deficiency is caused predominantly by a single point mutation, p.Pro73Leu. The mutation is associated with a significant thrombotic risk. Reduced AT activity caused by this mutation cannot be detected by all available screening methods. This must be taken into account in the choice of laboratory method used for screening.
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Affiliation(s)
- M Puurunen
- Hemostasis Laboratory, Finnish Red Cross Blood Service, Helsinki, Finland
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15
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Recurrent arterial thrombosis associated with the antithrombin basel variant and elevated lipoprotein(a) plasma level in an adolescent patient. J Pediatr Hematol Oncol 2012; 34:276-9. [PMID: 22134617 DOI: 10.1097/mph.0b013e3182331ecd] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Both myocardial infarction and ischemic stroke are rare in the young. Yet a 15-year-old male patient suffered a myocardial infarction and later an ischemic stroke despite uninterrupted antiplatelet therapy. His medical history involved the surgical correction of an incomplete atrioventricular canal defect at the age of 13 years. No cardiovascular risk factors other than elevated lipoprotein(a) level could be identified. His antithrombin (AT) activity was decreased and DNA sequence analysis revealed heterozygosity for AT Basel (p.Pro41Leu), a variant with impaired heparin binding. This report supports a possible additional pathophysiological role for AT Basel and elevated lipoprotein(a) level in arterial thrombogenesis.
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Amelioration of the severity of heparin-binding antithrombin mutations by posttranslational mosaicism. Blood 2012; 120:900-4. [PMID: 22498748 DOI: 10.1182/blood-2012-01-406207] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The balance between actions of procoagulant and anticoagulant factors protects organisms from bleeding and thrombosis. Thus, antithrombin deficiency increases the risk of thrombosis, and complete quantitative deficiency results in intrauterine lethality. However, patients homozygous for L99F or R47C antithrombin mutations are viable. These mutations do not modify the folding or secretion of the protein, but abolish the glycosaminoglycan-induced activation of antithrombin by affecting the heparin-binding domain. We speculated that the natural β-glycoform of antithrombin might compensate for the effect of heparin-binding mutations. We purified α- and β-antithrombin glycoforms from plasma of 2 homozygous L99F patients. Heparin affinity chromatography and intrinsic fluorescence kinetic analyses demonstrated that the reduced heparin affinity of the α-L99F glycoform (K(D), 107.9 ± 3nM) was restored in the β-L99F glycoform (K(D), 53.9 ± 5nM) to values close to the activity of α-wild type (K(D), 43.9 ± 0.4nM). Accordingly, the β-L99F glycoform was fully activated by heparin. Similar results were observed for recombinant R47C and P41L, other heparin-binding antithrombin mutants. In conclusion, we identified a new type of mosaicism associated with mutations causing heparin-binding defects in antithrombin. The presence of a fully functional β-glycoform together with the activity retained by these variants helps to explain the viability of homozygous and the milder thrombotic risk of heterozygous patients with these specific antithrombin mutations.
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17
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Melo FR, Pereira MS, Monteiro RQ, Foguel D, Mourão PAS. Sulfated galactan is a catalyst of antithrombin-mediated inactivation of alpha-thrombin. Biochim Biophys Acta Gen Subj 2008; 1780:1047-53. [PMID: 18558097 DOI: 10.1016/j.bbagen.2008.05.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 05/20/2008] [Accepted: 05/20/2008] [Indexed: 11/16/2022]
Abstract
Novel compounds presenting anticoagulant activity, such as sulfated polysaccharides, open new perspectives in medicine. Elucidation of the molecular mechanism behind this activity is desirable by itself, as well as because it allows for the design of novel compounds. In the present study, we investigated the action of an algal sulfated galactan, which potentiates alpha-thrombin inactivation by antithrombin. Our results indicate the following: 1) both the sulfated galactan and heparin potentiate protease inactivation by antithrombin at similar molar concentrations, however they differ markedly in the molecular size required for their activities; 2) this galactan interacts predominantly with exosite II on alpha-thrombin and, similar to heparin, catalyzes the formation of a covalent complex between antithrombin and the protease; 3) the sulfated galactan has a higher affinity for alpha-thrombin than for antithrombin. We propose that the preferred pathway of sulfated galactan-induced inactivation of alpha-thrombin by antithrombin starts with the polysaccharide binding to the protease through a high-affinity interaction. Antithrombin is then added to the complex and the protease is inactivated by covalent interactions. Finally, the antithrombin-alpha-thrombin covalent complex dissociates from the polysaccharide chain. This mechanism resembles the action of heparin with low affinity for antithrombin, as opposed to heparin with high affinity for serpin.
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Affiliation(s)
- Fábio R Melo
- Laboratório de Tecido Conjuntivo, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Caixa Postal 68041, Rio de Janeiro, RJ, 21941-590, Brazil
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18
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Melo FR, Pereira MS, Foguel D, Mourão PAS. Antithrombin-mediated anticoagulant activity of sulfated polysaccharides: different mechanisms for heparin and sulfated galactans. J Biol Chem 2004; 279:20824-35. [PMID: 14996843 DOI: 10.1074/jbc.m308688200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We investigated the mechanisms of anticoagulant activity mediated by sulfated galactans. The anticoagulant activity of sulfated polysaccharides is achieved mainly through potentiation of plasma cofactors, which are the natural inhibitors of coagulation proteases. Our results indicated the following. 1) Structural requirements for the interaction of sulfated galactans with coagulation inhibitors and their target proteases are not merely a consequence of their charge density. 2) The structural basis of this interaction is complex because it involves naturally heterogeneous polysaccharides but depends on the distribution of sulfate groups and on monosaccharide composition. 3) Sulfated galactans require significantly longer chains than heparin to achieve anticoagulant activity. 4) Possibly, it is the bulk structure of the sulfated galactan, and not a specific minor component as in heparin, that determines its interaction with antithrombin. 5) Sulfated galactans of approximately 15 to approximately 45 kDa bind to antithrombin but are unable to link the plasma inhibitor and thrombin. This last effect requires a molecular size above 45 kDa. 6) Sulfated galactan and heparin bind to different sites on antithrombin. 7) Sulfated galactans are less effective than heparin at promoting antithrombin conformational activation. Overall, these observations indicate that a different mechanism predominates over the conformational activation of antithrombin in ensuring the antithrombin-mediated anticoagulant activity of the sulfated galactans. Possibly, sulfated galactan connects antithrombin and thrombin, holding the protease in an inactive form. The conformational activation of antithrombin and the consequent formation of a covalent complex with thrombin appear to be less important for the anticoagulant activity of sulfated galactan than for heparin. Our results demonstrate that the paradigm of heparin-antithrombin interaction cannot be extended to other sulfated polysaccharides. Each type of polysaccharide may form a particular complex with the plasma inhibitor and the target protease.
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Affiliation(s)
- Fábio R Melo
- Laboratório de Tecido Conjuntivo, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Caixa Postal 68041, Rio de Janeiro, RJ 21941-590, Brazil
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19
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Fitton HL, Skinner R, Dafforn TR, Jin L, Pike RN. The N-terminal segment of antithrombin acts as a steric gate for the binding of heparin. Protein Sci 1998; 7:782-8. [PMID: 9541411 PMCID: PMC2143940 DOI: 10.1002/pro.5560070328] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The binding of heparin causes a conformational change in antithrombin to give an increased heparin binding affinity and activate the inhibition of thrombin and factor Xa. The areas of antithrombin involved in binding heparin and stabilizing the interaction in the high-affinity form have been partially resolved through the study of both recombinant and natural variants. The role of a section of the N-terminal segment of antithrombin, residues 22-46 (segment 22-46), in heparin binding was investigated using rapid kinetic analysis of the protein cleaved at residues 29-30 by limited proteolysis with thermolysin. The cleaved antithrombin had 5.5-fold lowered affinity for heparin pentasaccharide and 1.8-fold for full-length, high-affinity heparin. It was shown that, although the initial binding of heparin is slightly enhanced by the cleavage, it dissociates much faster from the cleaved form, giving rise to the overall decrease in heparin affinity. This implies that the segment constituting residues 22-46 in the N terminus of antithrombin hinders access to the binding site for heparin, hence the increased initial binding for the cleaved form, whereas, when heparin is bound, segment 22-46 is involved in the stabilization of the binding interaction, as indicated by the increased dissociation constant. When the heparin pentasaccharide is bound to antithrombin prior to incubation with thermolysin, it protects the N-terminal cleavage site, implying that segment 22-46 moves to interact with heparin in the conformational change and thus stabilizes the complex.
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Affiliation(s)
- H L Fitton
- Department of Haematology, University of Cambridge, MRC Centre, United Kingdom.
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20
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Walenga JM, Jeske WP, Bara L, Samama MM, Fareed J. Biochemical and pharmacologic rationale for the development of a synthetic heparin pentasaccharide. Thromb Res 1997; 86:1-36. [PMID: 9172284 DOI: 10.1016/s0049-3848(97)00042-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J M Walenga
- Department of Pathology, Loyola University Medical Center, Maywood, Illinois 60153, USA
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21
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22
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Abstract
Antithrombin is the major proteinase inhibitor of thrombin and other blood coagulation proteinases. Antithrombin has two functional domains, a heparin binding site and a reactive centre (that complexes and inactivates the proteinase). Its deficiency results in an increased risk of venous thromboembolism. Appreciable progress has been made in recent years in understanding the structure and function of this protein, the genetic cause of inherited deficiency and its clinical consequence. The structure of antithrombin is now considered in terms of the models derived from X-ray crystallography, which have provided explanations for the function of its heparin interaction site and of its reactive loop. The structural organization of the antithrombin gene has been defined and numerous mutations have been identified that are responsible for antithrombin deficiency: these may reduce the level of the protein (Type I deficiency), alter the function of the protein (Type II deficiency, altering heparin binding or reactive sites), or even have multiple or 'pleiotropic effects' (Type II deficiency, altering both functional domains and the level of protein).
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Affiliation(s)
- D A Lane
- Department of Haematology, Charing Cross and Westminister Medical School, Hammersmith, London, UK
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23
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Abstract
Human antithrombin is the major plasma inhibitor of thrombin both in the presence and absence of heparin. Its physiological importance is emphasised by the recurrent thromboses that individuals with a deficient or functionally abnormal protein are prone to develop. Such deficiencies are estimated to affect as many as 1:630 of the general population and between 3% and 5% of patients with thrombotic disease. The gene for antithrombin (AT3) has been cloned and shown to map to the long arm of chromosome 1 at 1q23-25. The gene consists of seven exons and six introns and spans 13,477bp of DNA. Advances in molecular genetic techniques have facilitated identification of the underlying DNA mutation(s) in > 80 families with antithrombin deficiency. Such work has proved invaluable in structure-function studies and in helping to provide informed genetic counselling to "at-risk" individuals based upon the natural history of similar variants.
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Affiliation(s)
- D J Perry
- Department of Haematology, University of Cambridge, United Kingdom
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24
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Chowdhury V, Mille B, Olds RJ, Lane DA, Watton J, Barrowcliffe TW, Pabinger I, Woodcock BE, Thein SL. Antithrombins Southport (Leu 99 to Val) and Vienna (Gln 118 to Pro): two novel antithrombin variants with abnormal heparin binding. Br J Haematol 1995; 89:602-9. [PMID: 7734360 DOI: 10.1111/j.1365-2141.1995.tb08369.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report the characterization of three variant antithrombins with reduced heparin binding as the primary abnormality. Two of these variants, antithrombin Southport (Leu 99 to Val, 2759 C to G) and antithrombin Vienna (Gln 118 to Pro, 5349 A to C) were novel, whereas the third, Pro 41 to Leu, has been previously described as antithrombin Basel. All three variants exhibited reduced binding for heparin on crossed immunoelectrophoresis and in a quantitative monoclonal antibody-based assay. The mutations were characterized by direct sequence analysis of enzymatically amplified genomic DNA and all affected individuals were heterozygous for the mutations. These three mutations do not occur at the sites of the basic amino acids directly involved in heparin binding nor do they result in a change in charge of the affected residue. It seems probable that they reduce heparin affinity either by perturbing the initial contact site involved in the heparin-binding domain (Arg 47, Arg 129 and possibly Arg 24), or by preventing the subsequent heparin-induced conformational change.
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Affiliation(s)
- V Chowdhury
- Institute of Molecular Medicine, Oxford, U.K
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25
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Stein PE, Carrell RW. What do dysfunctional serpins tell us about molecular mobility and disease? NATURE STRUCTURAL BIOLOGY 1995; 2:96-113. [PMID: 7749926 DOI: 10.1038/nsb0295-96] [Citation(s) in RCA: 331] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Proteinase inhibitors of the serpin family have a unique ability to regulate their activity by changing the conformation of their reactive-centre loop. Although this may explain their evolutionary success, the dependence of function on structural mobility makes the serpins vulnerable to the effects of mutations. Here, we describe how studies of dysfunctional variants, together with crystal structures of serpins in different forms, provide insights into the molecular functions and remarkable folding properties of this family. In particular, comparisons of variants affecting different serpins allow us to define the domains which control this folding and show how spontaneous but inappropriate changes in conformation cause diverse diseases.
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Affiliation(s)
- P E Stein
- Department of Haematology, University of Cambridge, MRC Centre, UK
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26
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27
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Stone SR, Brown-Luedi ML, Rovelli G, Guidolin A, McGlynn E, Monard D. Localization of the heparin-binding site of glia-derived nexin/protease nexin-1 by site-directed mutagenesis. Biochemistry 1994; 33:7731-5. [PMID: 8011637 DOI: 10.1021/bi00190a028] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recombinant rat glia-derived nexin was expressed in insect cells using the baculovirus system. The kinetics for the inhibition of thrombin by this recombinant material were indistinguishable from those observed with natural glia-derived nexin and recombinant nexin expressed in yeast. In addition, the dependence of the rate of inactivation on the concentration of heparin was similar for the three preparations. At the optimal heparin concentration, the association rate constant was 330-fold higher than that observed in the absence of heparin. A putative heparin-binding site is found in glia-derived nexin between residues 71 and 86; heparin-binding sites are found in homologous regions of antithrombin III and heparin cofactor II. Lysines in this region were mutated to glutamates, and the kinetics for the inhibition of thrombin by mutant proteins were determined. Concurrent mutation of all seven lysines in this region (residues 71, 74, 75, 78, 83, 84, and 86) did not affect the rate constant for the association of glia-derived nexin with thrombin in the absence of heparin, but it resulted in complete loss of the heparin acceleration of the rate of association. Mutations of residues 83, 84, and 86 together also caused a marked decrease in the acceleration by heparin of the reaction between glia-derived nexin and thrombin. These results support the hypothesis that the heparin-binding sites of glia-derived nexin, antithrombin III, and heparin cofactor II are found in homologous regions of the molecules. Heparin was also found to potentiate the ability of wild-type glia-derived nexin to inhibit the thrombin-induced retraction of neurites from neuroblastoma NB2a cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S R Stone
- Department of Haematology, University of Cambridge, MRC Centre, U.K
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28
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Affiliation(s)
- R J Olds
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford
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29
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Abstract
Human antithrombin is the major inhibitor of the coagulation serine proteases accounting for approximately 80% of the thrombin inhibitory activity of plasma. It is a member of the serpin family of serine protease inhibitors and in common with some other members of this family it undergoes a dramatic increase in its inhibitory activity in the presence of heparin and other sulphated glycosaminoglycans. Two functional domains in antithrombin are recognised, the reactive site domain which interacts with the active site serine residue of the protease and the heparin binding domain. The gene for antithrombin has been cloned and its entire nucleotide sequence determined. A deficiency or functional abnormality of antithrombin may result in an increased risk of thromboembolic disease. Such deficiencies are estimated to affect as many as 1:300 of the general population and 3 to 5% of patients with thrombotic disease. On the basis of functional and immunological antithrombin assays, antithrombin deficiency may be subdivided into Types I and II. Type I disease is due to a wide variety of heterogeneous DNA mutations whilst in Type II disease missense mutations leading to single amino acid substitutions have been identified in all cases. Clinically, Type I antithrombin deficiency is associated with recurrent thromboembolic disease whereas in Type II deficiency the risk of thrombosis is closely related to the position of the mutation within the protein. Thus, heterozygotes with mutations within the heparin binding domain of antithrombin have a relatively low risk of thrombosis compared to those with mutations at or close to the reactive site of the molecule.
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Affiliation(s)
- D J Perry
- Department of Haematology, University of Cambridge, MRC Centre, UK
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30
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Najjam S, Chadeuf G, Gandrille S, Aiach M. Arg-129 plays a specific role in the conformation of antithrombin and in the enhancement of factor Xa inhibition by the pentasaccharide sequence of heparin. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1225:135-43. [PMID: 8280781 DOI: 10.1016/0925-4439(94)90070-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Small amounts of a variant antithrombin (AT) bearing an Arg-129 to Gln mutation were purified from plasma by means of affinity chromatography on insolubilized heparin at very low ionic strength. As a control, two variant antithrombins, one bearing a Pro-41 to Leu mutation and the other an Arg-47 to His mutation, were purified in the same way. The biochemical characterization of the variants and the kinetic study of thrombin and activated factor X (F Xa) inhibition in the presence of heparin and heparin derivatives suggest that Arg-129 plays a specific role in AT conformation and F Xa inhibition enhancement. Indeed, the purified variant adopted the locked conformation described for AT submitted to mild denaturing conditions (Carrell, R.W., Evans, D.Li. and Stein, P.E. (1991) Nature 353, 576-578) and resembling the latent form of plasminogen activator inhibitor (PAI) (Mottonen, J., Strand, A., Symersky, J., Sweet, R.M., Danley, D.E., Geoghegan, K.F., Gerard, R.D. and Goldsmith, E.J. (1992) Nature 355, 270-273). Moreover, the mutant AT was partially reactivated by heparin for thrombin inhibition, but did not respond to the specific pentasaccharide domain of heparin for F Xa inhibition.
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Affiliation(s)
- S Najjam
- Groupe de Recherche sur la Thrombose, INSERM CJF 91-01, UFR des Sciences Pharmaceutiques et Biologiques, Paris, France
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31
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Nishioka J, Suzuki K. The role of the COOH-terminal region of antithrombin III. Evidence that the COOH-terminal region of the inhibitor enhances the reactivity of thrombin and factor Xa with the inhibitor. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41658-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Olds RJ, Lane DA, Boisclair M, Sas G, Bock SC, Thein SL. Antithrombin Budapest 3. An antithrombin variant with reduced heparin affinity resulting from the substitution L99F. FEBS Lett 1992; 300:241-6. [PMID: 1555650 DOI: 10.1016/0014-5793(92)80854-a] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The molecular basis and functional properties of a variant antithrombin (AT) protein. AT Budapest 3, were studied. A single base substitution was identified in codon 99, CTC----TTC, altering the normal leucine to phenylalanine. The proband presented with a history of venous thrombotic disease and was found to be homozygous for the mutation. The variant protein demonstrated reduced heparin affinity and reduced antiproteinase activity in the presence of either unfractionated heparin or the AT-binding heparin pentasaccharide, when compared to normal AT. A small change in the isoelectric point was also identified. The substituted amino acid residue of AT Budapest 3 is located near to the proposed AT heparin binding site, and it is suggested that reduced heparin affinity of the variant protein may result from substitution-induced distortion of positive charge geometry in the binding site and/or changes in its position relative to the rest of the inhibitor molecule.
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Affiliation(s)
- R J Olds
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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33
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Nakagawa M, Tanaka S, Tsuji H, Takada O, Uno M, Hashimoto-Gotoh T, Wagatsuma M. Congenital antithrombin III deficiency (AT-III Kyoto): identification of a point mutation altering arginine-406 to methionine behind the reactive site. Thromb Res 1991; 64:101-8. [PMID: 1776135 DOI: 10.1016/0049-3848(91)90209-f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A Japanese patient with congenital antithrombin III (AT-III) deficiency, named AT-III Kyoto, is associated with reduced levels (60% of normal) of AT-III antigen, progressive activity and heparin cofactor activity. The antithrombin III gene of this patient was investigated by polymerase chain reaction (PCR) method followed by direct DNA sequencing analysis, which revealed a G to T transitional mutation resulting in the conversion of arginine-406 to methionine in exon 6. Arginine-406 is located at the 12th amino acid residue from the reactive site on the C-terminal side of AT-III in a core region of the molecule which has been highly conserved during evolution of serine protease inhibitor (serpin) family. It is concluded that AT-III Kyoto is a newly described mutation which is similar to AT-III Utah and lends support to the idea that the conserved region near the reactive site is important in maintaining biological function of the AT-III molecule.
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Affiliation(s)
- M Nakagawa
- Second Department of Medicine, Kyoto Prefectural University of Medicine, Japan
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35
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Mejdoub H, Le Ret M, Boulanger Y, Maman M, Choay J, Reinbolt J. The complete amino acid sequence of bovine antithrombin (ATIII). JOURNAL OF PROTEIN CHEMISTRY 1991; 10:205-12. [PMID: 1930634 DOI: 10.1007/bf01024785] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bovine antithrombin (ATIII) is a glycoprotein of Mr 56,600. Its primary structure was established using peptide sequences from five different digests. Bovine ATIII exhibits four glcosylation sites as well as human ATIII. The primary structures of bovine and human ATIII were compared: all the residues required for the integrity of the heparin-binding domain are strictly conserved. However, there are differences in the secondary structures of both proteins, bovine and human ATIII.
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Affiliation(s)
- H Mejdoub
- Laboratoire de Biochimie, Centre National de la Recherche Scientifique, Strasbourg, France
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36
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Harper PL, Luddington RJ, Daly M, Bruce D, Williamson D, Edgar PF, Perry DJ, Carrell RW. The incidence of dysfunctional antithrombin variants: four cases in 210 patients with thromboembolic disease. Br J Haematol 1991; 77:360-4. [PMID: 2012760 DOI: 10.1111/j.1365-2141.1991.tb08584.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
210 patients, with a history of venous thrombosis, have undergone prothrombotic investigations. In nine cases a consistent deficiency of antithrombin was identified. In five there was a reduction in the plasma antigenic concentration of antithrombin and in a further four cases deficiency was due to the presence of a dysfunctional antithrombin variant. The variants have all been characterized by DNA analysis and in three the mutations have been confirmed by peptide sequencing (antithrombin Basel (41 Pro to Leu). Hamilton (382 Ala to Thr). Cambridge I (384 Ala to Pro) and Cambridge II (384 Ala to Ser). The incidence of antithrombin deficiency in patients with a history of venous thrombosis has previously been quoted at between 2% and 3%: there is no published data available on the incidence of antithrombin variants. In our series 5% of patients who presented before the age of 40 years had antithrombin deficiency, and 2% of the total number of patients investigated had a dysfunctional variant. Our figures indicate that a significant number of cases of antithrombin deficiency are due to dysfunctional variants and that the true incidence of antithrombin deficiency in patients with a history of venous thrombosis is in the order of 5%.
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Affiliation(s)
- P L Harper
- Department of Haematology, University of Cambridge
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37
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Abstract
Inherited defects of antithrombin III, protein C, protein S, heparin cofactor II, plasminogen and the fibrinogens are thought to be responsible for between 10 and 15% of all patients presenting with recurrent venous thrombosis. The structure, function and expression of these genes and the nature of the gene lesions underlying the deficiency states are reviewed in detail.
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Affiliation(s)
- D N Cooper
- Molecular Genetics Section, Thrombosis Research Institute, Chelsea, London, UK
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38
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Brennan SO, Borg JY, Shaw GJ, Caen J, George PM. Functional antithrombin-III variant (41 Pro----Leu) identified by liquid secondary ion mass spectrometry. Pathology 1991; 23:1-4. [PMID: 2062560 DOI: 10.3109/00313029109061429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A genetic variant of antithrombin with impaired heparin cofactor activity was identified in 4 members of a French family. Both the variant and normal antithrombin component were purified by affinity chromatography on heparin Sepharose. Reverse phase peptide mapping revealed a single altered peak when tryptic digests of both antithrombins were compared. After further purification of the aberrant peptide, amino acid analysis indicated a substitution of 41 Leu----Pro (antithrombin Basel). This result was confirmed by liquid secondary ion mass spectrometry which gave a measured mass of 816.4655 Da for the new peptide compared to a calculated mass of 800.3579 Da for the normal peptide and 816.4579 for the Leu----Pro substitution.
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Affiliation(s)
- S O Brennan
- Department of Clinical Biochemistry, Christchurch Hospital, New Zealand
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39
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Ragg H, Ulshöfer T, Gerewitz J. Glycosaminoglycan-mediated leuserpin-2/thrombin interaction. Structure-function relationships. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45717-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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40
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Gandrille S, Aiach M, Lane D, Vidaud D, Molho-Sabatier P, Caso R, de Moerloose P, Fiessinger J, Clauser E. Important role of arginine 129 in heparin-binding site of antithrombin III. Identification of a novel mutation arginine 129 to glutamine. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)30614-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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Owen BA, Owen WG. Interaction of factor Xa with heparin does not contribute to the inhibition of factor Xa by antithrombin III-heparin. Biochemistry 1990; 29:9412-7. [PMID: 2248954 DOI: 10.1021/bi00492a015] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Factor Xa modified by reductive methylation (greater than 92%) loses the capacity to bind heparin as determined both by gel chromatography and by sedimentation equilibrium ultracentrifugation. The kinetic properties of methylated factor Xa differ, with respect to KM and Vmax for a synthetic tripeptide substrate and for antithrombin III inhibition rate constants, from those of the unmodified enzyme. The 10,000-fold rate enhancement elicited by the addition of heparin to the antithrombin III inhibition reaction, however, is the same. The observed second-order rate constants (k"obs) for antithrombin III inhibition of factor Xa and methylated factor Xa are 3000 and 340 M-1 s-1, respectively, whereas k"obs values for the inhibition of factor Xa or methylated factor Xa with antithrombin III-heparin are 4 X 10(7) and 3 X 10(6) M-1 s-1, respectively. These findings provide direct evidence that the interaction of factor Xa with heparin is not involved in the heparin-enhanced inhibition of this enzyme.
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Affiliation(s)
- B A Owen
- Section of Hematology Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905
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42
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Sun XJ, Chang JY. Evidence that arginine-129 and arginine-145 are located within the heparin binding site of human antithrombin III. Biochemistry 1990; 29:8957-62. [PMID: 2271571 DOI: 10.1021/bi00490a011] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Arginyl residues of human antithrombin III have been implicated to involve in the heparin binding site [Jorgensen, A. M., Borders, C. L., & Fish, W. W. (1985) Biochem, J. 231, 59-63]. We have performed chemical modification of antithrombin with (p-hydroxyphenyl)glyoxal (HPG) in order to determine the locations of these arginine residues. Antithrombin was modified with 12 mM HPG in the absence and presence of heparin (2-fold by weight to antithrombin). In the absence of heparin, about 3-4 mol of arginines/mol of antithrombin were modified within 60 min, and the modification led to the loss of 95% of the inhibitor's heparin cofactor activity as well as heparin-induced fluorescence enhancement and 50% of its progressive inhibitory activity. In the presence of heparin, the extent of modification was diminished by 30% and modified antithrombin retained approximately 70% of its heparin cofactor activity. Peptide mapping and subsequent sequence analysis revealed that selective HPG modification occurred at Arg129 and Arg145 and that their modifications were protected upon binding of heparin to antithrombin. We conclude that Arg129 and Arg145 are situated within the heparin binding site of human antithrombin III.
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Affiliation(s)
- X J Sun
- Pharmaceuticals Research Laboratories, Ciba-Geigy Ltd., Basel, Switzerland
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43
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Mourey L, Samama JP, Delarue M, Choay J, Lormeau JC, Petitou M, Moras D. Antithrombin III: structural and functional aspects. Biochimie 1990; 72:599-608. [PMID: 2126464 DOI: 10.1016/0300-9084(90)90123-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Antithrombin III is a plasma glycoprotein responsible for thrombin inhibition in the blood coagulation cascade. The X-ray structure of its cleaved form has been determined and refined to 3.2 A resolution. The overall topology is similar to that of alpha 1-antitrypsin, another member of the serpin (serine protease inhibitor) superfamily. The biological activity of antithrombin III is mediated by a polysaccharide, heparin. The binding site of this effector is described. A possible structural transition from the native to the cleaved structure is discussed.
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Affiliation(s)
- L Mourey
- Laboratoire de Cristallographie Biologique, IBMC du CNRS, Strasbourg, France
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44
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Borg JY, Brennan SO, Carrell RW, George P, Perry DJ, Shaw J. Antithrombin Rouen-IV 24 Arg----Cys. The amino-terminal contribution to heparin binding. FEBS Lett 1990; 266:163-6. [PMID: 2365065 DOI: 10.1016/0014-5793(90)81530-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A variant antithrombin with reduced heparin affinity was shown by mass spectrometry sequencing and DNA amplification to have a substitution of a cysteine for an arginine at residue 24. The position of Arg-24 can be fixed within a 12 A radius from the bridge at Cys-21. This is compatible with findings in the homologous protease nexin-1 which indicate an extension of the binding site of heparin from the D-helix to under the adjacent amino-terminal pole.
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Affiliation(s)
- J Y Borg
- Laboratoire d'hemostase, Centre Hospitalier Universitaire, Rouen, France
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45
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de Roux N, Chadeuf G, Molho-Sabatier P, Plouin PF, Aiach M. Clinical and biochemical characterization of antithrombin III Franconville, a variant with Pro 41 Leu mutation. Br J Haematol 1990; 75:222-7. [PMID: 2372510 DOI: 10.1111/j.1365-2141.1990.tb02653.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We describe a familial study of AT III, a type III antithrombin III variant which was identified in the propositus by gene analysis as Pro 41 Leu heterozygous mutation. None of the four members of the family who presented with defective heparin cofactor (hep-cofactor) activity, and therefore probably carried the mutation, had experienced deep venous thrombosis. The abnormal AT III was purified from the propositus' plasma, taking advantage of the difference in NaCl concentrations required to elute variant and normal AT III from heparin-Sepharose. The antithrombin and anti-Xa activities of the purified variant AT III were comparable to those observed for normal AT III, but hep-cofactor activity was strikingly reduced. The enhancement by heparin of thrombin and F Xa inhibition by normal and variant AT III was compared in the absence of NaCl and in the presence of normal NaCl concentrations. The difference between the degrees of inhibition by normal and variant AT III was maximal at physiological ionic strength (i.e. at a concentration of 0.15 M). The quantification of heparin AT III interaction with both normal and variant purified proteins in a double reciprocal plot yielded similar dissociation constants but a 9-fold decrease in the maximal pseudo-first order constant. This suggests that Pro 41 is more involved in the molecular changes induced by heparin than in the primary binding of the activator.
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Affiliation(s)
- N de Roux
- Laboratoire de Recherche en Hémostase, Hôpital Broussais, Paris, France
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46
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Caso R, Lane DA, Thompson E, Zangouras D, Panico M, Morris H, Olds RJ, Thein SL, Girolami A. Antithrombin Padua. I: Impaired heparin binding caused by an Arg47 to his (CGT to CAT) substitution. Thromb Res 1990; 58:185-90. [PMID: 2349545 DOI: 10.1016/0049-3848(90)90175-c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- R Caso
- Department of Haematology, Charing Cross and Westminster Medical School, London, UK
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47
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Affiliation(s)
- C H Beresford
- Department of Pathology, Otago Medical School, University of Otago, Dunedin, New Zealand
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48
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Samama JP, Delarue M, Mourey L, Choay J, Moras D. Crystallization and preliminary crystallographic data for bovine antithrombin III. J Mol Biol 1989; 210:877-9. [PMID: 2614848 DOI: 10.1016/0022-2836(89)90116-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Crystals of bovine antithrombin III were obtained in the presence of metal ions with ammonium sulphate as precipitating agent. Crystals belong to space group P4(1)2(1)2 or P4(3)2(1)2 with cell parameters a = b = 91.4 A, c = 383.1 A; there are two molecules per asymmetric unit. Electrophoresis experiments and amino acid sequence analysis of the N-terminal part of redissolved crystals suggest that the protein molecules are cleaved at the active site.
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Affiliation(s)
- J P Samama
- Laboratoire de Cristallographie Biologique, I.B.M.C. du C.N.R.S., Strasbourg, France
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49
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Daly M, Ball R, O'Meara A, Hallinan FM. Identification and characterisation of an antithrombin III mutant (AT Dublin 2) with marginally decreased heparin reactivity. Thromb Res 1989; 56:503-13. [PMID: 2609289 DOI: 10.1016/0049-3848(89)90234-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The antithrombin III (ATIII) isoform patterns of plasma and serum samples from cancer patients and controls were analysed by isoelectric focusing and immunoblotting. A novel ATIII banding pattern was identified in two individuals: a patient with breast carcinoma who developed deep venous thrombosis and a blood donor. Family studies in the patient showed the abnormal pattern to be due to a mutant form of ATIII (AT Dublin 2). The coagulation properties of AT Dublin 2 heterozygotes were normal. Immunologic and activity levels of ATIII, measured by standard techniques, were normal. Mutant plasma ATIII showed reduced thrombin reactivity at low concentrations of thrombin and demonstrated decreased reactivity with heparin over a range of heparin concentrations. This was confirmed using a modified ATIII heparin cofactor activity assay with varying heparin concentrations. The abnormal ATIII was also found to elute from heparin agarose at a lower ionic strength than normal ATIII. Two dimensional gel electrophoresis showed the abnormal ATIII to have similar molecular size distribution to normal ATIII. Neuraminidase treatment of normal and mutant plasma reduced the ATIII isoforms to one in both samples. The possible role of AT Dublin 2 in predisposing to hypercoagulation is discussed.
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Affiliation(s)
- M Daly
- Children's Research Centre, Our Lady's Hospital for Sick Children, Dublin, Ireland
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50
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Lane DA, Caso R. Antithrombin: structure, genomic organization, function and inherited deficiency. BAILLIERE'S CLINICAL HAEMATOLOGY 1989; 2:961-98. [PMID: 2688761 DOI: 10.1016/s0950-3536(89)80054-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Antithrombin is a major plasma protein inhibitor of proteinases generated during blood coagulation; it plays an important role in the regulation of thrombin in blood. The anticoagulant heparin greatly accelerates the rate of inactivation of proteinases by antithrombin, predominantly through its well defined, highly specific binding reaction with the inhibitor, but also through a less strictly defined interaction with some of the proteinases (such as thrombin). There is evidence for an analogous acceleratory mechanism in vivo, that functions by the binding of antithrombin to a subpopulation of heparan sulphate proteoglycans intercalated in the surface of endothelial cells. The location and structure of the gene for antithrombin are known. Both its overall organization and the structure of the subdomains of the expressed protein can be considered in terms of their relationships to a serine proteinase inhibitor superfamily, which is believed to have evolved from a common ancestor. The region of the antithrombin gene 5' to the coding region has been characterized. Unlike other members of the serpin family, there is no TATA-like promoter sequence. Two enhancer sequences have been identified that are homologous to enhancer regions of other genes. There are two polymorphisms: an intragenic polymorphism arising from a translationally silent A to G transition in codon 305, and a length polymorphism arising from the presence of 32 bp or 108 bp non-homologous sequences 345 bp upstream from the translation initiation codon. Inherited deficiency of antithrombin is associated with familial thromboembolism. The molecular genetic basis of some subtypes of deficiency is increasingly yielding to investigation. It is interesting to note that a number of mutations have been identified in CpG dinucleotides, supporting the suggestion that this dinucleotide sequence may represent a mutation hotspot in the human genome.
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