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Childers KC, Peters SC, Lollar P, Spencer HT, Doering CB, Spiegel PC. SAXS analysis of the intrinsic tenase complex bound to a lipid nanodisc highlights intermolecular contacts between factors VIIIa/IXa. Blood Adv 2022; 6:3240-3254. [PMID: 35255502 PMCID: PMC9198903 DOI: 10.1182/bloodadvances.2021005874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 02/27/2022] [Indexed: 11/20/2022] Open
Abstract
The intrinsic tenase (Xase) complex, formed by factors (f) VIIIa and fIXa, forms on activated platelet surfaces and catalyzes the activation of factor X to Xa, stimulating thrombin production in the blood coagulation cascade. The structural organization of the membrane-bound Xase complex remains largely unknown, hindering our understanding of the structural underpinnings that guide Xase complex assembly. Here, we aimed to characterize the Xase complex bound to a lipid nanodisc with biolayer interferometry (BLI), Michaelis-Menten kinetics, and small-angle X-ray scattering (SAXS). Using immobilized lipid nanodiscs, we measured binding rates and nanomolar affinities for fVIIIa, fIXa, and the Xase complex. Enzyme kinetic measurements demonstrated the assembly of an active enzyme complex in the presence of lipid nanodiscs. An ab initio molecular envelope of the nanodisc-bound Xase complex allowed us to computationally model fVIIIa and fIXa docked onto a flexible lipid membrane and identify protein-protein interactions. Our results highlight multiple points of contact between fVIIIa and fIXa, including a novel interaction with fIXa at the fVIIIa A1-A3 domain interface. Lastly, we identified hemophilia A/B-related mutations with varying severities at the fVIIIa/fIXa interface that may regulate Xase complex assembly. Together, our results support the use of SAXS as an emergent tool to investigate the membrane-bound Xase complex and illustrate how mutations at the fVIIIa/fIXa dimer interface may disrupt or stabilize the activated enzyme complex.
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Affiliation(s)
- Kenneth C Childers
- Department of Chemistry, Western Washington University, Bellingham, WA; and
| | - Shaun C Peters
- Department of Chemistry, Western Washington University, Bellingham, WA; and
| | - Pete Lollar
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Emory University, Atlanta, GA
| | - Harold Trent Spencer
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Emory University, Atlanta, GA
| | - Christopher B Doering
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Emory University, Atlanta, GA
| | - Paul C Spiegel
- Department of Chemistry, Western Washington University, Bellingham, WA; and
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2
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Abstract
INTRODUCTION Hemophilia A (HA) or B (HB) is an X-linked recessive disorder caused by a defect in the factor VIII (FVIII) or factor IX (FIX) gene which leads to the dysfunction of blood coagulation. Protein replacement therapy (PRT) uses recombinant proteins and plasma-derived products, which incurs high cost and inconvenience requiring routine intravenous infusions and life-time treatment. Understanding of detailed molecular mechanisms on FVIII gene function could provide innovative solutions to amend this disorder. In recent decades, gene therapeutics have advanced rapidly and a one-time cure solution has been proposed. AREAS COVERED This review summarizes current understanding of molecular pathways involved in blood coagulation, with emphasis on FVIII's functional role. The existing knowledge and challenges on FVIII gene expression, from transcription, translation, post-translational modification including glycosylation to protein processing and secretion, and co-factor interactions are deciphered and potential molecular interventions discussed. EXPERT OPINION This article reviews the potential treatment targets for HA and HB, including antibodies, small molecules and gene therapeutics, based on molecular mechanisms of FVIII biosynthesis, and further, assessing the pros and cons of these various treatment strategies. Understanding detailed FVIII protein synthesis and secretory pathways could provide exciting opportunities in identifying novel therapeutics to ameliorate hemophilia state.
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Affiliation(s)
- Jie Gong
- School of Medicine, University of Electronic Science and Technology of China, Sichuan, China
| | - Hao-Lin Wang
- School of Medicine, University of Electronic Science and Technology of China, Sichuan, China
| | - Lung-Ji Chang
- School of Medicine, University of Electronic Science and Technology of China, Sichuan, China.,Geno-Immune Medical Institute, Shenzhen, China
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3
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Abstract
The formation of membrane-bound complexes between specific coagulation factors at different cell surfaces is required for effective blood clotting. The most important of these complexes, the intrinsic Tenase and Prothrombinase complexes, are formed on the activated platelet surface during the propagation phase of coagulation. These two complexes are highly specific in their assembly mechanism and function modulated by anionic membranes, thus offering desirable targets for pharmaceutical interventions. Factor V (FV) and factor VIII (FVIII) are highly homologous non-enzymatic proteins. In their active state, FVa and FVIIIa serve as cofactors for the respective serine proteases factor Xa (FXa) and factor IXa (FIXa), significantly increasing their catalytic activity. This is achieved by forming well organized membrane-bound complexes at the phosphatidylserine rich activated platelet membrane in the presence of Ca2+ ions. The tenase (FVIIIa/FIXa) complex, catalyzes the proteolytic conversion of FX to FXa. Subsequently the prothrombinase (FVa/FXa) complex catalyzes the conversion of prothrombin to thrombin, required for efficient blood clotting. Although significant knowledge of FV and FVIII biochemistry and regulation has been achieved, the molecular mechanisms of their function are yet to be defined. Understanding the geometric assembly of the tenase and prothrombinase complexes is paramount in defining the structural basis of bleeding and thrombotic disorders. Such knowledge will enable the design of efficient pro- and anticoagulant therapies critical for regulating abnormal hemostasis. In this chapter, we will summarize the findings to date, showing our achievement in the field and outlining the future findings required to grasp the complexity of these proteins.
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Affiliation(s)
- Svetla Stoilova-McPhie
- Center for Nanoscale Systems (CNS), Laboratory For Integrated Sciences and Engineering (LISE), Faculty of Art and Sciences (FAS), Harvard University, 11 Oxford Street, Cambridge, MA, 02138, England, UK.
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Dalm D, Galaz-Montoya JG, Miller JL, Grushin K, Villalobos A, Koyfman AY, Schmid MF, Stoilova-McPhie S. Dimeric Organization of Blood Coagulation Factor VIII bound to Lipid Nanotubes. Sci Rep 2015; 5:11212. [PMID: 26082135 PMCID: PMC4469981 DOI: 10.1038/srep11212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 05/05/2015] [Indexed: 11/09/2022] Open
Abstract
Membrane-bound Factor VIII (FVIII) has a critical function in blood coagulation as the pro-cofactor to the serine-protease Factor IXa (FIXa) in the FVIIIa-FIXa complex assembled on the activated platelet membrane. Defects or deficiency of FVIII cause Hemophilia A, a mild to severe bleeding disorder. Despite existing crystal structures for FVIII, its membrane-bound organization has not been resolved. Here we present the dimeric FVIII membrane-bound structure when bound to lipid nanotubes, as determined by cryo-electron microscopy. By combining the structural information obtained from helical reconstruction and single particle subtomogram averaging at intermediate resolution (15-20 Å), we show unambiguously that FVIII forms dimers on lipid nanotubes. We also demonstrate that the organization of the FVIII membrane-bound domains is consistently different from the crystal structure in solution. The presented results are a critical step towards understanding the mechanism of the FVIIIa-FIXa complex assembly on the activated platelet surface in the propagation phase of blood coagulation.
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Affiliation(s)
- Daniela Dalm
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jesus G Galaz-Montoya
- 1] Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA [2] National Center for Macromolecular Imaging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jaimy L Miller
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Kirill Grushin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Alex Villalobos
- School of Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Alexey Y Koyfman
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Michael F Schmid
- 1] Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA [2] National Center for Macromolecular Imaging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Svetla Stoilova-McPhie
- 1] Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA [2] Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
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5
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Saadi S, Saari N, Anwar F, Abdul Hamid A, Ghazali HM. Recent advances in food biopeptides: Production, biological functionalities and therapeutic applications. Biotechnol Adv 2015; 33:80-116. [DOI: 10.1016/j.biotechadv.2014.12.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 02/05/2014] [Accepted: 12/05/2014] [Indexed: 10/24/2022]
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Quade-Lyssy P, Abriss D, Milanov P, Ungerer C, Königs C, Seifried E, Schüttrumpf J. Next generation FIX muteins with FVIII-independent activity for alternative treatment of hemophilia A. J Thromb Haemost 2014; 12:1861-73. [PMID: 25224783 DOI: 10.1111/jth.12731] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 08/06/2014] [Indexed: 01/15/2023]
Abstract
BACKGROUND FVIII neutralizing antibodies are the main complication of substitution therapy in hemophilia A (HA); auto-antibodies against FVIII causing acquired HA can also occur. Treatment of inhibitor patients remains challenging because prophylactic treatment with existing FVIII bypassing agents, all based on constitutively active coagulation factors, is difficult due to their short half-life. OBJECTIVES To generate zymogenic FIX variants with FVIII-independent activity for gene- and protein-based therapy for HA. METHODS Modifications were introduced into FIX based on current knowledge of FIX structure and FVIII-independent function followed by random screening. Activity, thrombin generation and FX activation by FIX mutants were characterized in the presence and absence of FVIII. Phenotype correction of promising candidates was assessed by the tail-clip assay in FVIII-knockout mice. RESULTS About 1600 clones were screened and three mutations (L6F, S102N and E185D) identified, which improved FVIII-independent activity in combination with our previously described variant FIX-ITV. By systematic combination of all mutations, six FIX mutants with the desired bypassing activity were designed. Candidate mutants FIX-IDAV and FIX-FIAV demonstrated the most efficient thrombin generation in FVIII-deficient plasma and had considerably increased activities towards FX in the absence of FVIII, in that they showed an up to 5-fold increase in catalytic efficiency. Expression of FIX-IDAV in FVIII knockout mice reduced blood loss after the tail-clip assay, even in the presence of neutralizing FVIII antibodies. CONCLUSION Activatable bioengineered FIX molecules (as opposed to pre-activated coagulation factors) with FVIII-independent activity might be a promising tool for improving HA treatment, especially for patients with inhibitors.
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Affiliation(s)
- P Quade-Lyssy
- German Red Cross Blood Donor Service Baden-Württemberg-Hessen, Institute of Transfusion Medicine and Immunohematology of the Goethe University Clinics, Frankfurt am Main, Germany
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7
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Venkateswarlu D. Structural insights into the interaction of blood coagulation co-factor VIIIa with factor IXa: a computational protein-protein docking and molecular dynamics refinement study. Biochem Biophys Res Commun 2014; 452:408-14. [PMID: 25157807 DOI: 10.1016/j.bbrc.2014.08.078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 08/18/2014] [Indexed: 11/16/2022]
Abstract
Coagulation factor X (FX) zymogen activation by factor IXa (FIXa) enzyme plays a critical role in the middle-phase of coagulation cascade. The activation process is catalytically inert and requires FIXa binding and complex formation with co-factor VIIIa (FVIIIa). In order to understand the structural details of the FVIIIa:FIXa complex, we employed knowledge-driven protein-protein docking and aqueous-phase MD refinement methods to develop a stable structural complex between FVIIIa and FIXa. The model shows that all four domains of FIXa wrap across FVIIIa that spans the co-factor binding surface of A2, A3 and C1 domains. The region surrounding the 558-helix of the A2-domain of FVIIIa is predicted to be the key interaction site with the helical segments of Lys293-Lys301 and Asp332-Arg338 residues of the serine-protease domain of FIXa. The hydrophobic helical stack between the GLA and EGF1 domains of FIXa is predicted to be primary interacting region with the A3-C2 domain interface of FVIIIa.
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Affiliation(s)
- Divi Venkateswarlu
- Department of Chemistry, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA.
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8
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Stoilova-McPhie S, Lynch GC, Ludtke S, Pettitt BM. Domain organization of membrane-bound factor VIII. Biopolymers 2013; 99:448-59. [PMID: 23616213 PMCID: PMC4090243 DOI: 10.1002/bip.22199] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/13/2012] [Accepted: 11/18/2012] [Indexed: 11/07/2022]
Abstract
Factor VIII (FVIII) is the blood coagulation protein which when defective or deficient causes for hemophilia A, a severe hereditary bleeding disorder. Activated FVIII (FVIIIa) is the cofactor to the serine protease factor IXa (FIXa) within the membrane-bound Tenase complex, responsible for amplifying its proteolytic activity more than 100,000 times, necessary for normal clot formation. FVIII is composed of two noncovalently linked peptide chains: a light chain (LC) holding the membrane interaction sites and a heavy chain (HC) holding the main FIXa interaction sites. The interplay between the light and heavy chains (HCs) in the membrane-bound state is critical for the biological efficiency of FVIII. Here, we present our cryo-electron microscopy (EM) and structure analysis studies of human FVIII-LC, when helically assembled onto negatively charged single lipid bilayer nanotubes. The resolved FVIII-LC membrane-bound structure supports aspects of our previously proposed FVIII structure from membrane-bound two-dimensional (2D) crystals, such as only the C2 domain interacts directly with the membrane. The LC is oriented differently in the FVIII membrane-bound helical and 2D crystal structures based on EM data, and the existing X-ray structures. This flexibility of the FVIII-LC domain organization in different states is discussed in the light of the FVIIIa-FIXa complex assembly and function.
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Affiliation(s)
- Svetla Stoilova-McPhie
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, USA.
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9
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10
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Qureshi SH, Yang L, Rezaie AR. Contribution of the NH2-terminal EGF-domain of factor IXa to the specificity of intrinsic tenase. Thromb Haemost 2012; 108:1154-64. [PMID: 23014580 DOI: 10.1160/th12-06-0436] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/03/2012] [Indexed: 11/05/2022]
Abstract
Factor IXa (FIXa) is a vitamin K-dependent coagulation serine protease which binds to factor VIIIa (FVIIIa) on negatively charged phospholipid vesicles (PCPS) to catalyse the activation of factor X (FX) to factor Xa (FXa) in the intrinsic pathway. Fluorescence resonance energy transfer (FRET) studies have indicated that the Gla-domain-dependent interaction of FIXa and FX with PCPS in the presence of FVIIIa positions the active-site of the protease at an appropriate height above the membrane surface to optimise the catalytic reaction. In this study, we investigated the contribution of the NH2-terminal EGF-domain (EGF1) of FIXa to the recognition specificity of intrinsic tenase by constructing an EGF1 deletion mutant of FIXa (FIXa-desEGF1) and characterising the properties of the mutant in kinetic, direct binding and FRET assays. The results of direct binding and kinetic studies demonstrated that the binding affinity of the mutant for interaction with FVIIIa on PCPS has been impaired greater than 10-fold and the catalytic efficiency of the mutant protease-FVIIIa-PCPS complex in the activation of FX has been decreased ~100-fold. By contrast, the mutant protease exhibited a normal activity toward FX in the absence of the protein cofactor. FRET measurements revealed that the distance of the active-site of the mutant FIXa relative to PCPS vesicles has been decreased 10 Å from 75 ± 2 Å for FIXa to 65 ± 2 Å for FIXa-desEGF1 independent of FVIIIa. These results suggest that the NH2-terminal EGF-domain of FIXa provides a binding-site for FVIIIa and plays an essential spacer function in the intrinsic tenase complex.
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Affiliation(s)
- Shabir H Qureshi
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
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11
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Gilbert GE, Novakovic VA, Kaufman RJ, Miao H, Pipe SW. Conservative mutations in the C2 domains of factor VIII and factor V alter phospholipid binding and cofactor activity. Blood 2012; 120:1923-32. [PMID: 22613792 PMCID: PMC3433094 DOI: 10.1182/blood-2012-01-408245] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 05/01/2012] [Indexed: 11/20/2022] Open
Abstract
Factor VIII and factor V share structural homology and bind to phospholipid membranes via tandem, lectin-like C domains. Their respective C2 domains bind via 2 pairs of hydrophobic amino acids and an amphipathic cluster. In contrast, the factor V-like, homologous subunit (Pt-FV) of a prothrombin activator from Pseudonaja textilis venom is reported to function without membrane binding. We hypothesized that the distinct membrane-interactive amino acids of these proteins contribute to the differing membrane-dependent properties. We prepared mutants in which the C2 domain hydrophobic amino acid pairs were changed to the homologous residues of the other protein and a factor V mutant with 5 amino acids changed to those from Pt-FV (FV(MTTS/Y)). Factor VIII mutants were active on additional membrane sites and had altered apparent affinities for factor X. Some factor V mutants, including FV(MTTS/Y), had increased membrane interaction and apparent membrane-independent activity that was the result of phospholipid retained during purification. Phospholipid-free FV(MTTS/Y) showed increased activity, particularly a 10-fold increase in activity on membranes lacking phosphatidylserine. The reduced phosphatidylserine requirement correlated to increased activity on resting and stimulated platelets. We hypothesize that altered membrane binding contributes to toxicity of Pt-FV.
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Affiliation(s)
- Gary E Gilbert
- Department of Medicine, Veterans Administration Boston Healthcare System, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA, USA.
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12
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Peng HT, Blostein MD, Shek PN. Characterization of In Vitro Hemostatic Peptide Effects by Thromboelastography. Clin Appl Thromb Hemost 2011; 18:27-34. [DOI: 10.1177/1076029611412371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In this study, we validated a thromboelastography (TEG) method to evaluate the hemostatic effects of 3 peptides. The first peptide is an ideal amphipathic peptide composed of 22 leucine and lysine in a ratio of 2:1. At a very low concentration, the peptide had a procoagulant effect shown by decreases in reaction time (R) and coagulation time (K) but was impaired by a decrease in maximum amplitude (MA). At higher concentrations, the peptide had an anticoagulant effect. The α angle was minimally affected by the peptide. The second peptide is melittin derived from bee venom. Melittin showed procoagulant effects reflected by a decrease in clotting time but led to lower MA. The third peptide derived from fibrinogen γ chain promoted hemostasis only at an optimal concentration and became anticoagulant at a higher concentration. The hemostatic mechanisms of each peptide were discussed. Our study would facilitate further development of peptides for either hemorrhage control or thrombosis treatment.
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Affiliation(s)
- Henry T. Peng
- Defence Research and Development Canada, Toronto, Ontario, Canada
| | - Mark D. Blostein
- Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Pang N. Shek
- Defence Research and Development Canada, Toronto, Ontario, Canada
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13
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Abstract
Factor VIII functions as a cofactor for Factor IXa in a membrane-bound enzyme complex. Membrane binding accelerates the activity of the Factor VIIIa-Factor IXa complex approx. 100000-fold, and the major phospholipid-binding motif of Factor VIII is thought to be on the C2 domain. In the present study, we prepared an fVIII-C2 (Factor VIII C2 domain) construct from Escherichia coli, and confirmed its structural integrity through binding of three distinct monoclonal antibodies. Solution-phase assays, performed with flow cytometry and FRET (fluorescence resonance energy transfer), revealed that fVIII-C2 membrane affinity was approx. 40-fold lower than intact Factor VIII. In contrast with the similarly structured C2 domain of lactadherin, fVIII-C2 membrane binding was inhibited by physiological NaCl. fVIII-C2 binding was also not specific for phosphatidylserine over other negatively charged phospholipids, whereas a Factor VIII construct lacking the C2 domain retained phosphatidyl-L-serine specificity. fVIII-C2 slightly enhanced the cleavage of Factor X by Factor IXa, but did not compete with Factor VIII for membrane-binding sites or inhibit the Factor Xase complex. Our results indicate that the C2 domain in isolation does not recapitulate the characteristic membrane binding of Factor VIII, emphasizing that its role is co-operative with other domains of the intact Factor VIII molecule.
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Microparticles in stored red blood cells: submicron clotting bombs? BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2010; 8 Suppl 3:s31-8. [PMID: 20606747 DOI: 10.2450/2010.006s] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Misenheimer TM, Sheehan JP. The regulation of factor IXa by supersulfated low molecular weight heparin. Biochemistry 2010; 49:9997-10005. [PMID: 20945941 DOI: 10.1021/bi100906q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Supersulfated low molecular weight heparin (ssLMWH) inhibits the intrinsic tenase (factor IXa-factor VIIIa) complex in an antithrombin-independent manner. Recombinant factor IXa with alanine substitutions in the protease domain (K126A, N129A, K132A, R165A, R170A, N178A, R233A) was assessed with regard to heparin affinity in solution and ability to regulate protease activity within the factor IXa-phospholipid (PL) and intrinsic tenase complexes. In a soluble binding assay, factor IXa K126A, K132A, and R233A dramatically (10-20-fold) reduced ssLMWH affinity, while factor IXa N129A and R165A moderately (5-fold) reduced affinity relative to wild type. In the factor IXa-PL complex, binding affinity for ssLMWH was increased 4-fold, and factor X activation was inhibited with a potency 7-fold higher than predicted for wild-type protease-ssLMWH affinity in solution. In the intrinsic tenase complex, ssLMWH inhibited factor X activation with a 4-fold decrease in potency relative to wild-type factor IXa-PL. The mutations increased resistance to inhibition by ssLMWH in a similar fashion for both enzyme complexes (R233A > K126A > K132A/R165A > N129A/N178A/wild type) except for factor IXa R170A. This protease had ssLMWH affinity and potency for the factor IXa-PL complex similar to wild-type protease but was moderately resistant (6-fold) to inhibition in the intrinsic tenase complex based on increased cofactor affinity. These results are consistent with conformational regulation of the heparin-binding exosite and macromolecular substrate catalysis by factor IXa. An extensive overlap exists between the heparin and factor VIIIa binding sites on the protease domain, with residues K126 and R233 dominating the heparin interaction and R165 dominating the cofactor interaction.
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Affiliation(s)
- Tina M Misenheimer
- Department of Medicine/Hematology-Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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16
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Wakabayashi H, Griffiths AE, Fay PJ. Factor VIII lacking the C2 domain retains cofactor activity in vitro. J Biol Chem 2010; 285:25176-84. [PMID: 20529839 DOI: 10.1074/jbc.m110.106906] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Factor (F) VIII consists of a heavy chain (A1A2B domains) and light chain (A3C1C2 domains). The activated form of FVIII, FVIIIa, functions as a cofactor for FIXa in catalyzing the membrane-dependent activation of FX. Whereas the FVIII C2 domain is believed to anchor FVIIIa to the phospholipid surface, recent x-ray crystal structures of FVIII suggest that the C1 domain may also contribute to this function. We constructed a FVIII variant lacking the C2 domain (designated DeltaC2) to characterize the contributions of the C1 domain to function. Binding affinity of the DeltaC2 variant to phospholipid vesicles as measured by energy transfer was reduced approximately 14-fold. However, the activity of DeltaC2 as measured by FXa generation and one-stage clotting assays retained 76 and 36%, respectively, of the WT FVIII value. Modest reductions ( approximately 4-fold) were observed in the functional affinity of DeltaC2 FVIII for FIXa and rates of thrombin activation. On the other hand, deletion of C2 resulted in significant reductions in FVIIIa stability ( approximately 3.6-fold). Thrombin generation assays showed peak thrombin and endogenous thrombin potential were reduced as much as approximately 60-fold. These effects likely result from a combination of the intermolecular functional defects plus reduced protein stability. Together, these results indicate that FVIII domains other than C2, likely C1, make significant contributions to membrane-binding and membrane-dependent function.
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Affiliation(s)
- Hironao Wakabayashi
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, New York 14642, USA
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Abstract
Abstract
Blood haemostasis is accomplished by a complex network of coagulatory and fibrinolytic processes. These processes have to be delicately balanced, as clinically manifested by bleeding disorders, such as haemophilia A and B. These disorders are caused by defects in coagulation factor VIII and factor IX, respectively. Following a dual strategy, we emphasise on the one hand principles conserved in most coagulation enzymes, thus mirroring much of the underlying complexity in haemostasis; on the other hand, we identify enzymatic properties of the factor IXa-factor VIIIa system (Xase) that distinguish this proteolytic machine from other components of the coagulation system. While the exact mechanisms of its activity modulation remain baffling until today, superactive factor IX mutants significantly improve our current understanding and serve as a specific and testable model of Xase action.
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Affiliation(s)
- Thomas Zögg
- Department of Molecular Biology, Division of Structural Biology, University of Salzburg, Billrothstraße 11, A-5020 Salzburg, Austria
| | - Hans Brandstetter
- Department of Molecular Biology, Division of Structural Biology, University of Salzburg, Billrothstraße 11, A-5020 Salzburg, Austria
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19
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MUKHERJEE S, SAHA A, BISWAS P, MANDAL C, RAY K. Structural analysis of factor IX protein variants to predict functional aberration causing haemophilia B. Haemophilia 2008; 14:1076-81. [DOI: 10.1111/j.1365-2516.2008.01788.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Crystal structure of human factor VIII: implications for the formation of the factor IXa-factor VIIIa complex. Structure 2008; 16:597-606. [PMID: 18400180 DOI: 10.1016/j.str.2008.03.001] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2008] [Revised: 02/27/2008] [Accepted: 03/01/2008] [Indexed: 11/24/2022]
Abstract
Factor VIII is a procofactor that plays a critical role in blood coagulation, and is missing or defective in hemophilia A. We determined the X-ray crystal structure of B domain-deleted human factor VIII. This protein is composed of five globular domains and contains one Ca(2+) and two Cu(2+) ions. The three homologous A domains form a triangular heterotrimer where the A1 and A3 domains serve as the base and interact with the C2 and C1 domains, respectively. The structurally homologous C1 and C2 domains reveal membrane binding features. Based on biochemical studies, a model of the factor IXa-factor VIIIa complex was constructed by in silico docking. Factor IXa wraps across the side of factor VIII, and an extended interface spans the factor VIII heavy and light chains. This model provides insight into the activation of factor VIII and the interaction of factor VIIIa with factor IXa on the membrane surface.
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Yang L, Gopalakrishna K, Manithody C, Rezaie AR. Expression, purification and characterization of factor IX derivatives using a novel vector system. Protein Expr Purif 2006; 50:196-202. [PMID: 16829135 DOI: 10.1016/j.pep.2006.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 05/23/2006] [Indexed: 11/23/2022]
Abstract
Recent studies have indicated that the loop harboring the S1 specificity site (residues 185-189 in chymotrypsin numbering) of coagulation proteases has several charged residues with important structural and functional roles for the catalytic activity of these proteases. This loop is allosterically linked to the Na(+)-binding site in both factor Xa and thrombin. There are three candidate residues (His-185, Glu-186, and Arg-188) on this loop of factor IXa (fIXa) whose side chains can influence the Na(+) binding and the catalytic function of the protease in the intrinsic Xase complex. In this study, we developed a novel expression/purification vector system, substituted all three residues of factor IX individually with Ala, and expressed the mutant zymogens in mammalian cells. Following activation, all three fIXa mutants exhibited normal activity towards a fIXa-specific chromogenic substrate in the presence of Ca(2+) with no obvious requirement for Na(+) in the reaction. Furthermore, all three mutants interacted with factor VIIIa with near normal affinity and catalyzed the activation of factor X in the intrinsic Xase complex with a normal catalytic efficiency. These results suggest that, unlike thrombin and factor Xa, the charged residues of this loop do not play a functional role in modulating the catalytic function of fIXa in the intrinsic Xase complex.
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Affiliation(s)
- Likui Yang
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
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22
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Autin L, Steen M, Dahlbäck B, Villoutreix BO. Proposed structural models of the prothrombinase (FXa-FVa) complex. Proteins 2006; 63:440-50. [PMID: 16437549 DOI: 10.1002/prot.20848] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Activated coagulation factor V (FVa) functions as a cofactor to factor Xa (FXa) in the conversion of prothrombin (PT) to thrombin. This essential procoagulant reaction, despite being the subject of extensive investigation, is not fully understood structurally and functionally. To elucidate the structure of the FXa-FVa complex, we have performed protein:protein (Pr:Pr) docking simulation with the pseudo-Brownian Pr:Pr docking ICM package and with the shape-complementarity Pr:Pr docking program PPD. The docking runs were carried out using a new model of full-length human FVa and the X-ray structure of human FXa. Five representative models of the FXa-FVa complex were in overall agreement with some of the available experimental data, but only one model was found to be consistent with almost all of the reported experimental results. The use of hybrid docking approach (theoretical plus experimental) is definitively important to study such large macromolecular complexes. The FXa-FVa model we have created will be instrumental for further investigation of this macromolecular system and will guide future site directed mutagenesis experiments.
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Hasanbasic I, Rajotte I, Blostein M. The role of gamma-carboxylation in the anti-apoptotic function of gas6. J Thromb Haemost 2005; 3:2790-7. [PMID: 16359517 DOI: 10.1111/j.1538-7836.2005.01662.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Gas6 is a novel member of the vitamin K-dependent family of gamma-carboxylated proteins and is a ligand for the receptor tyrosine kinase Axl. Gas6-Axl interactions have been shown to mediate cell survival in vascular endothelium. Although the receptor-binding portion of gas6 lies in the C-terminus, the significance of the N-terminal gamma-carboxylated residues (Gla domain) is not clear. To address this question, this study examines the role of the Gla domain in phospholipid binding as well as in the promotion of cell survival, especially in endothelial cells. The results show that carboxylated gas6 binds to phosphatidylserine-containing phospholipid membranes in an analogous manner to other gamma-carboxylated proteins whereas decarboxylated gas6 does not. The gamma-carboxylation inhibitor warfarin abrogates gas6-mediated protection of NIH3T3 fibroblasts from serum starvation-induced apoptosis. Furthermore, the role of gamma-carboxylation in gas6's survival effect on endothelium is demonstrated directly in that only carboxylated, but not decarboxylated, gas6 protects endothelial cells from serum starvation-induced apoptosis. gamma-carboxylation is also required for both Axl phosphorylation and PI3 kinase activation. Taken together, these findings demonstrate that gamma-carboxylation is necessary not only for gas6 binding to phospholipid membranes, but also for gas6-mediated endothelial cell survival.
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Affiliation(s)
- I Hasanbasic
- The Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
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24
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Autin L, Miteva MA, Lee WH, Mertens K, Radtke KP, Villoutreix BO. Molecular models of the procoagulant factor VIIIa-factor IXa complex. J Thromb Haemost 2005; 3:2044-56. [PMID: 16102111 DOI: 10.1111/j.1538-7836.2005.01527.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Formation of the intrinsic tenase complex is an essential event in the procoagulant reactions that lead to clot formation. The tenase complex is formed when the activated serine protease, Factor IXa (FIXa), and its cofactor Factor VIIIa (FVIIIa) assemble on a phospholipid surface to proteolytically convert the zymogen Factor X (FX) into its active form FXa. The physiological relevance of the tenase complex is evident in hemophilia A or B patients who present with bleeding disorders. OBJECTIVES The purpose of this study was to establish three-dimensional (3D) models of the FVIIIa-FIXa complex. METHODS First, we built two new theoretical models of FVIIIa via homology modeling, inter-domain docking and loop simulation algorithms as well as a model for FIXa. This was followed by pseudo-Brownian protein-protein docking in internal coordinates with the ICM (Internal Coordinates Mechanics) program between the two FVIIIa and the FIXa structures. RESULTS Ten representative models of this complex are presented based on agreements with known experimental data and according to structural criteria. CONCLUSIONS These novel 3D models will help guide future site directed mutagenesis aimed at improving the functionality of FVIIIa and/or FIXa and will contribute to a better understanding of the role of this macromolecular complex in the blood coagulation cascade.
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Affiliation(s)
- L Autin
- Inserm U648, Paris 5 University, 4 Ave de l'Observatoire, Paris, France
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25
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Schmidt AE, Stewart JE, Mathur A, Krishnaswamy S, Bajaj SP. Na+ site in blood coagulation factor IXa: effect on catalysis and factor VIIIa binding. J Mol Biol 2005; 350:78-91. [PMID: 15913649 DOI: 10.1016/j.jmb.2005.04.052] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 04/20/2005] [Accepted: 04/25/2005] [Indexed: 11/17/2022]
Abstract
During blood coagulation, factor IXa (FIXa) activates factor X (FX) requiring Ca2+, phospholipid, and factor VIIIa (FVIIIa). The serine protease domain of FIXa contains a Ca2+ site and is predicted to contain a Na+ site. Comparative homology analysis revealed that Na+ in FIXa coordinates to the carbonyl groups of residues 184A, 185, 221A, and 224 (chymotrypsin numbering). Kinetic data obtained at several concentrations of Na+ and Ca2+ with increasing concentrations of a synthetic substrate (CH3-SO2-d-Leu-Gly-Arg-p-nitroanilide) were fit globally, assuming rapid equilibrium conditions. Occupancy by Na+ increased the affinity of FIXa for the synthetic substrate, whereas occupancy by Ca2+ decreased this affinity but increased k(cat) dramatically. Thus, Na+-FIXa-Ca2+ is catalytically more active than free FIXa. FIXa(Y225P), a Na+ site mutant, was severely impaired in Na+ potentiation of its catalytic activity and in binding to p-aminobenzamidine (S1 site probe) validating that substrate binding in FIXa is linked positively to Na+ binding. Moreover, the rate of carbamylation of NH2 of Val16, which forms a salt-bridge with Asp194 in serine proteases, was faster for FIXa(Y225P) and addition of Ca2+ overcame this impairment only partially. Further studies were aimed at delineating the role of the FIXa Na+ site in macromolecular catalysis. In the presence of Ca2+ and phospholipid, with or without saturating FVIIIa, FIXa(Y225P) activated FX with similar K(m) but threefold reduced k(cat). Further, interaction of FVIIIa:FIXa(Y225P) was impaired fourfold. Our previous data revealed that Ca2+ binding to the protease domain increases the affinity of FIXa for FVIIIa approximately 15-fold. The present data indicate that occupancy of the Na+ site further increases the affinity of FIXa for FVIIIa fourfold and k(cat) threefold. Thus, in the presence of Ca2+, phospholipid, and FVIIIa, binding of Na+ to FIXa increases its biologic activity by approximately 12-fold, implicating its role in physiologic coagulation.
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Affiliation(s)
- Amy E Schmidt
- UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery and Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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Gudderra NP, Ribeiro JMC, Andersen JF. Structural Determinants of Factor IX(a) Binding in Nitrophorin 2, a Lipocalin Inhibitor of the Intrinsic Coagulation Pathway. J Biol Chem 2005; 280:25022-8. [PMID: 15866866 DOI: 10.1074/jbc.m504386200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitrophorin 2 (NP2) is a salivary lipocalin from Rhodnius prolixus that binds with coagulation factors IX (fIX) and IXa (fIXa). Binding of NP2 with fIXa results in potent inhibition of the intrinsic factor Xase complex. A panel of site-directed surface mutants of NP2 was generated to locate determinants of high affinity fIX(a) binding. The locations of the mutations were based on comparisons with the related, but less potent, inhibitor nitrophorin 3 (NP3). Three point mutants (K21A, K92A, and V94A) were found that clearly reduced the inhibitory potency as measured by the activity of a reconstituted factor Xase system. Binding of NP2 with fIXa and fIX as measured by surface plasmon resonance and isothermal titration calorimetry was reduced in a similar manner. Of the three mutants, two (K92A and V94A) were located on the loop connecting beta-strands E and F of the lipocalin beta-barrel. The largest changes were seen with the K92A mutation, which lies at the apex of the loop, with a smaller effect being seen with mutation of Val(94). Combination of four E-F loop mutations (K92A, A93K, V94A, E97A) in a single mutant reduced the inhibitory potency and binding to levels similar to those seen with NP3 without affecting heme or histamine binding.
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Affiliation(s)
- Nanda P Gudderra
- Laboratory of Malaria and Vector Research NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA
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Saller F, Villoutreix BO, Amelot A, Kaabache T, Le Bonniec BF, Aiach M, Gandrille S, Borgel D. The γ-carboxyglutamic acid domain of anticoagulant protein S is involved in activated protein C cofactor activity, independently of phospholipid binding. Blood 2005; 105:122-30. [PMID: 15308562 DOI: 10.1182/blood-2004-06-2176] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractWe expressed 2 chimeras between human protein S (PS) and human prothrombin (FII) in which the prothrombin γ-carboxyglutamic acid (Gla) domain replaced the PS Gla domain in native PS (GlaFII-PS) or in PS deleted of the thrombin-sensitive region (TSR) (GlaFII-ΔTSR-PS). Neither PS/FII chimera had activated protein C (APC) cofactor activity in plasma clotting assays or purified systems, but both bound efficiently to phospholipids. This pointed to a direct involvement of the PS Gla domain in APC cofactor activity through molecular interaction with APC. Using computational methods, we identified 2 opposite faces of solvent-exposed residues on the PS Gla domain (designated faces 1 and 2) as potentially involved in this interaction. Their importance was supported by functional characterization of a PS mutant in which the face 1 and face 2 PS residues were reintroduced into GlaFII-PS, leading to significant APC cofactor activity, likely through restored interaction with APC. Furthermore, by characterizing PS mutants in which PS face 1 and PS face 2 were individually replaced by the corresponding prothrombin faces, we found that face 1 was necessary for efficient phospholipid binding but that face 2 residues were not strictly required for phospholipid binding and were involved in the interaction with APC.
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Affiliation(s)
- François Saller
- Institut Natioanl de la Santé et de la Recherche Médicale U428, Faculté des Sciences Pharmaceutique et Biologiques, IFR 71 Sciences du Médicament, Université Paris V, France
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Yang X, Chang YJ, Lin SW, Walsh PN. Identification of Residues Asn89, Ile90, and Val107 of the Factor IXa Second Epidermal Growth Factor Domain That Are Essential for the Assembly of the Factor X-activating Complex on Activated Platelets. J Biol Chem 2004; 279:46400-5. [PMID: 15328360 DOI: 10.1074/jbc.m406552200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activated platelets promote intrinsic factor X-activating complex assembly by presenting high affinity, saturable binding sites for factor IXa mediated by two disulfide-constrained loop structures (loop 1, Cys88-Cys99; loop 2, Cys95-Cys109) within the second epidermal growth factor (EGF2) domain. To identify amino acids essential for factor X activation complex assembly, recombinant factor IXa point mutants in loop 1 (N89A, I90A, K91A, and R94A) and loop 2 (D104A, N105A, and V107A) were prepared. All seven mutants were similar to the native factor IXa by SDS-PAGE, active site titration, and content of gamma-carboxyglutamic acid residues. Kinetic constants obtained by either titrating factor X or factor VIIIa on SFLLRN-activated platelets or phospholipid vesicles revealed near normal values of Km(app) and Kd(app)FVIIIa for all mutants, indicating normal substrate and cofactor binding. In a factor Xa generation assay in the presence of activated platelets and cofactor factor VIIIa, compared with native factor IXa (Kd(app)FIXa approximately 1.1 nm, Vmax approximately 12 nm min(-1)), N89A displayed an increase of approximately 20-fold in Kd(app)FIXa and a decrease of approximately 20-fold in Vmax; I90A had an increase of approximately 5-fold in Kd(app)FIXa and approximately 10-fold decrease in Vmax; and V107A had an increase of approximately 3-fold in Kd(app)FIXa and approximately 4-fold decrease in Vmax. We conclude that residues Asn89, Ile90, and Val107 within loops 1 and 2 (Cys88-Cys109) of the EGF2 domain of factor IXa are essential for normal interactions with the platelet surface and for the assembly of the factor X-activating complex on activated platelets.
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Affiliation(s)
- Xia Yang
- Sol Sherry Thrombosis Research Center, Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Abstract
PURPOSE OF REVIEW The biochemistry of blood coagulation has been well defined over the past 50 years. Although much is known about the sequence of the proteolytic cascade and its regulation in the pathway to fibrin generation, many important questions remain unsolved about the mechanism of initiation and the structure of the protein complexes that form during blood coagulation. RECENT FINDINGS This article summarizes some of the advances that have been made in this field from the last quarter of 2002 and during 2003. The papers, which vary in rigor and content, have been selected on the basis of their interest and possible contribution to knowledge in this field. Summaries are given of new findings on the source of factor V and the synthesis of factor VIII, the mechanism of tissue factor action in the initiation of blood coagulation, the structure and membrane-binding properties of the protein complexes formed, and regulation of the blood coagulation cascade. SUMMARY Continued progress in this field offers opportunity for understanding the basis of thrombotic diseases and bleeding disorders, with the potential for defining novel targets for therapeutic applications. Some of the conclusions reviewed are conflicting, and further work will be necessary to place the results in the context of what has already been established. The structural biology of the coagulation proteins and understanding of hemostasis and thrombosis in a physiologic context have important implications for future work.
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Affiliation(s)
- Monica Schenone
- Center for Hemostasis, Thrombosis and Vascular Biology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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