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Lopes TJS, Nogueira T, Rios R. A Machine Learning Framework Predicts the Clinical Severity of Hemophilia B Caused by Point-Mutations. FRONTIERS IN BIOINFORMATICS 2022; 2:912112. [DOI: 10.3389/fbinf.2022.912112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
Blood coagulation is a vital physiological mechanism to stop blood loss following an injury to a blood vessel. This process starts immediately upon damage to the endothelium lining a blood vessel, and results in the formation of a platelet plug that closes the site of injury. In this repair operation, an essential component is the coagulation factor IX (FIX), a serine protease encoded by the F9 gene and whose deficiency causes hemophilia B. If not treated by prophylaxis or gene therapy, patients with this condition are at risk of life-threatening bleeding episodes. In this sense, a deep understanding of the FIX protein and its activated form (FIXa) is essential to develop efficient therapeutics. In this study, we used well-studied structural analysis techniques to create a residue interaction network of the FIXa protein. Here, the nodes are the amino acids of FIXa, and two nodes are connected by an edge if the two residues are in close proximity in the FIXa 3D structure. This representation accurately captured fundamental properties of each amino acid of the FIXa structure, as we found by validating our findings against hundreds of clinical reports about the severity of HB. Finally, we established a machine learning framework named HemB-Class to predict the effect of mutations of all FIXa residues to all other amino acids and used it to disambiguate several conflicting medical reports. Together, these methods provide a comprehensive map of the FIXa protein architecture and establish a robust platform for the rational design of FIX therapeutics.
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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] [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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Beauglehole AC, Roche Recinos D, Pegg CL, Lee YY, Turnbull V, Herrmann S, Marcellin E, Howard CB, Schulz BL. Recent advances in the production of recombinant factor IX: bioprocessing and cell engineering. Crit Rev Biotechnol 2022; 43:484-502. [PMID: 35430942 DOI: 10.1080/07388551.2022.2036691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Appropriate treatment of Hemophilia B is vital for patients' quality of life. Historically, the treatment used was the administration of coagulation Factor IX derived from human plasma. Advancements in recombinant technologies allowed Factor IX to be produced recombinantly. Successful recombinant production has triggered a gradual shift from the plasma derived origins of Factor IX, as it provides extended half-life and expanded production capacity. However, the complex post-translational modifications of Factor IX have made recombinant production at scale difficult. Considerable research has therefore been invested into understanding and optimizing the recombinant production of Factor IX. Here, we review the evolution of recombinant Factor IX production, focusing on recent developments in bioprocessing and cell engineering to control its post-translational modifications in its expression from Chinese Hamster Ovary (CHO) cells.
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Affiliation(s)
- Aiden C. Beauglehole
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
- CSL Innovation, Parkville, Victoria, Australia
| | - Dinora Roche Recinos
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
- CSL Innovation, Parkville, Victoria, Australia
| | - Cassandra L. Pegg
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia
| | | | - Victor Turnbull
- CSL Innovation, Bio21 Institute of Molecular Science and Biotechnology, Parkville, Victoria, Australia
| | - Susann Herrmann
- CSL Innovation, Bio21 Institute of Molecular Science and Biotechnology, Parkville, Victoria, Australia
| | - Esteban Marcellin
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
| | - Christopher B. Howard
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
| | - Benjamin L. Schulz
- ARC Training Centre for Biopharmaceutical Innovation, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia
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Shen G, Gao M, Cao Q, Li W. The Molecular Basis of FIX Deficiency in Hemophilia B. Int J Mol Sci 2022; 23:ijms23052762. [PMID: 35269902 PMCID: PMC8911121 DOI: 10.3390/ijms23052762] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/23/2022] [Accepted: 02/27/2022] [Indexed: 12/15/2022] Open
Abstract
Coagulation factor IX (FIX) is a vitamin K dependent protein and its deficiency causes hemophilia B, an X-linked recessive bleeding disorder. More than 1000 mutations in the F9 gene have been identified in hemophilia B patients. Here, we systematically summarize the structural and functional characteristics of FIX and the pathogenic mechanisms of the mutations that have been identified to date. The mechanisms of FIX deficiency are diverse in these mutations. Deletions, insertions, duplications, and indels generally lead to severe hemophilia B. Those in the exon regions generate either frame shift or inframe mutations, and those in the introns usually cause aberrant splicing. Regarding point mutations, the bleeding phenotypes vary from severe to mild in hemophilia B patients. Generally speaking, point mutations in the F9 promoter region result in hemophilia B Leyden, and those in the introns cause aberrant splicing. Point mutations in the coding sequence can be missense, nonsense, or silent mutations. Nonsense mutations generate truncated FIX that usually loses function, causing severe hemophilia B. Silent mutations may lead to aberrant splicing or affect FIX translation. The mechanisms of missense mutation, however, have not been fully understood. They lead to FIX deficiency, often by affecting FIX’s translation, protein folding, protein stability, posttranslational modifications, activation to FIXa, or the ability to form functional Xase complex. Understanding the molecular mechanisms of FIX deficiency will provide significant insight for patient diagnosis and treatment.
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Affiliation(s)
- Guomin Shen
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang 471023, China
- School of Basic Medical Science, Henan University of Science and Technology, Luoyang 471023, China
| | - Meng Gao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang 471023, China
- School of Basic Medical Science, Henan University of Science and Technology, Luoyang 471023, China
| | - Qing Cao
- Henan International Joint Laboratory of Thrombosis and Hemostasis, Henan University of Science and Technology, Luoyang 471023, China
- School of Basic Medical Science, Henan University of Science and Technology, Luoyang 471023, China
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
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Gao W, Xu Y, Liu H, Gao M, Cao Q, Wang Y, Cui L, Huang R, Shen Y, Li S, Yang H, Chen Y, Li C, Yu H, Li W, Shen G. Characterization of missense mutations in the signal peptide and propeptide of FIX in hemophilia B by a cell-based assay. Blood Adv 2020; 4:3659-3667. [PMID: 32766856 PMCID: PMC7422117 DOI: 10.1182/bloodadvances.2020002520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/06/2020] [Indexed: 11/20/2022] Open
Abstract
Many mutations in the signal peptide and propeptide of factor IX (FIX) cause hemophilia B. A FIX variants database reports 28 unique missense mutations in these regions that lead to FIX deficiency, but the underlying mechanism is known only for the mutations on R43 that interfere with propeptide cleavage. It remains unclear how other mutations result in FIX deficiency and why patients carrying the same mutation have different bleeding tendencies. Here, we modify a cell-based reporter assay to characterize the missense mutations in the signal peptide and propeptide of FIX. The results show that the level of secreted conformation-specific reporter (SCSR), which has a functional γ-carboxyglutamate (Gla) domain of FIX, decreases significantly in most mutations. The decreased SCSR level is consistent with FIX deficiency in hemophilia B patients. Moreover, we find that the decrease in the SCSR level is caused by several distinct mechanisms, including interfering with cotranslational translocation into the endoplasmic reticulum, protein secretion, γ-carboxylation of the Gla domain, and cleavage of the signal peptide or propeptide. Importantly, our results also show that the SCSR levels of most signal peptide and propeptide mutations increase with vitamin K concentration, suggesting that the heterogeneity of bleeding tendencies may be related to vitamin K levels in the body. Thus, oral administration of vitamin K may alleviate the severity of bleeding tendencies in patients with missense mutations in the FIX signal peptide and propeptide regions.
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Affiliation(s)
- Wenwen Gao
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Yaqi Xu
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Hongli Liu
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Meng Gao
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Qing Cao
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Yiyi Wang
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Longteng Cui
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Rong Huang
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Yan Shen
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Sanqiang Li
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Haiping Yang
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
- First Affiliated Hospital, Henan University of Science and Technology, Luoyang, People's Republic of China
| | - Yixiang Chen
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
| | - Chaokun Li
- Sino-UK Joint Laboratory for Brain Function and Injury, School of Basic Medical Sciences, and
| | - Haichuan Yu
- Department of Biochemistry and Molecular Biology, School of Medical Laboratory, Xinxiang Medical University, Xinxiang, People's Republic of China; and
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Guomin Shen
- Department of Medical Genetics, Institute of Hemostasis and Thrombosis, School of Basic Medical Sciences, and
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Superwarfarin (Long-Acting Anticoagulant Rodenticides) Poisoning: from Pathophysiology to Laboratory-Guided Clinical Management. Clin Biochem Rev 2019; 40:175-185. [PMID: 31857739 DOI: 10.33176/aacb-19-00029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Superwarfarins are long-acting anticoagulant rodenticides developed from warfarin. The mechanism of action is by inhibition of vitamin K epoxide reductase, resulting in the inability of the body to recycle vitamin K. Deficiency of vitamin K thereafter leads to inability for the body to synthesise vitamin K-dependent coagulation factors, factor II, VII, IX, and X, leading to prolonged prothrombin time. Due to the bulky aromatic sidechains, superwarfarins have a much longer half-life when compared to warfarin, and exposure to superwarfarins results in a prolonged period of anticoagulation which can result in clinical bleeding. Diagnosis is straightforward in patients with known history of superwarfarin exposure but has proved difficult for patients who did not report superwarfarin intake. Superwarfarin poisoning should therefore be suspected in all patients with unexplained prolongation of prothrombin time, and can be confirmed by their detection in serum. Treatment for superwarfarin poisoning includes rapid correction of factor deficiencies with either 4-factor prothrombin complex concentrate or fresh frozen plasma in patients with active bleeding, and high dose vitamin K therapy given multiple times per day for a prolonged period of weeks to months.
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Muller MP, Wang Y, Morrissey JH, Tajkhorshid E. Lipid specificity of the membrane binding domain of coagulation factor X. J Thromb Haemost 2017; 15:2005-2016. [PMID: 28782177 PMCID: PMC5630516 DOI: 10.1111/jth.13788] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 01/19/2023]
Abstract
Essentials Membrane-binding GLA domains of coagulation factors are essential for proper clot formation. Factor X (FX) is specific to phosphatidylserine (PS) lipids through unknown atomic-level interactions. Molecular dynamics simulations were used to develop the first membrane-bound model of FX-GLA. PS binding modes of FX-GLA were described, and potential PS-specific binding sites identified. SUMMARY Background Factor X (FX) binds to cell membranes in a highly phospholipid-dependent manner and, in complex with tissue factor and factor VIIa (FVIIa), initiates the clotting cascade. Experimental information concerning the membrane-bound structure of FX with atomic resolution has remained elusive because of the fluid nature of cellular membranes. FX is known to bind preferentially to phosphatidylserine (PS). Objectives To develop the first membrane-bound model of the FX-GLA domain to PS at atomic level, and to identify PS-specific binding sites of the FX-GLA domain. Methods Molecular dynamics (MD) simulations were performed to develop an atomic-level model for the FX-GLA domain bound to PS bilayers. We utilized a membrane representation with enhanced lipid mobility, termed the highly mobile membrane mimetic (HMMM), permitting spontaneous membrane binding and insertion by FX-GLA in multiple 100-ns simulations. In 14 independent simulations, FX-GLA bound spontaneously to the membrane. The resulting membrane-bound models were converted from HMMM to conventional membrane and simulated for an additional 100 ns. Results The final membrane-bound FX-GLA model allowed for detailed characterization of the orientation, insertion depth and lipid interactions of the domain, providing insight into the molecular basis of its PS specificity. All binding simulations converged to the same configuration despite differing initial orientations. Conclusions Analysis of interactions between residues in FX-GLA and lipid-charged groups allowed for potential PS-specific binding sites to be identified. This new structural and dynamic information provides an additional step towards a full understanding of the role of atomic-level lipid-protein interactions in regulating the critical and complex clotting cascade.
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Affiliation(s)
- Melanie P. Muller
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - Yan Wang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - James H. Morrissey
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
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8
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Bah A, Forman-Kay JD. Modulation of Intrinsically Disordered Protein Function by Post-translational Modifications. J Biol Chem 2016; 291:6696-705. [PMID: 26851279 DOI: 10.1074/jbc.r115.695056] [Citation(s) in RCA: 347] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Post-translational modifications (PTMs) produce significant changes in the structural properties of intrinsically disordered proteins (IDPs) by affecting their energy landscapes. PTMs can induce a range of effects, from local stabilization or destabilization of transient secondary structure to global disorder-to-order transitions, potentially driving complete state changes between intrinsically disordered and folded states or dispersed monomeric and phase-separated states. Here, we discuss diverse biological processes that are dependent on PTM regulation of IDPs. We also present recent tools for generating homogenously modified IDPs for studies of PTM-mediated IDP regulatory mechanisms.
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Affiliation(s)
- Alaji Bah
- From the Program in Molecular Structure & Function, The Hospital for Sick Children, Toronto, Ontario M5G 0A4 and the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Julie D Forman-Kay
- From the Program in Molecular Structure & Function, The Hospital for Sick Children, Toronto, Ontario M5G 0A4 and the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Vanderslice NC, Messer AS, Vadivel K, Bajaj SP, Phillips M, Fatemi M, Xu W, Velander WH. Quantifying vitamin K-dependent holoprotein compaction caused by differential γ-carboxylation using high-pressure size exclusion chromatography. Anal Biochem 2015; 479:6-14. [PMID: 25804408 PMCID: PMC4428943 DOI: 10.1016/j.ab.2015.03.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 03/09/2015] [Accepted: 03/15/2015] [Indexed: 11/19/2022]
Abstract
This study uses high-pressure size exclusion chromatography (HPSEC) to quantify divalent metal ion (X(2+))-induced compaction found in vitamin K-dependent (VKD) proteins. Multiple X(2+) binding sites formed by the presence of up to 12 γ-carboxyglutamic acid (Gla) residues are present in plasma-derived FIX (pd-FIX) and recombinant FIX (r-FIX). Analytical ultracentrifugation (AUC) was used to calibrate the Stokes radius (R) measured by HPSEC. A compaction of pd-FIX caused by the filling of Ca(2+) and Mg(2+) binding sites resulted in a 5 to 6% decrease in radius of hydration as observed by HPSEC. The filling of Ca(2+) sites resulted in greater compaction than for Mg(2+) alone where this effect was additive or greater when both ions were present at physiological levels. Less X(2+)-induced compaction was observed in r-FIX with lower Gla content populations, which enabled the separation of biologically active r-FIX species from inactive ones by HPSEC. HPSEC was sensitive to R changes of approximately 0.01nm that enabled the detection of FIX compaction that was likely cooperative in nature between lower avidity X(2+) sites of the Gla domain and higher avidity X(2+) sites of the epidermal growth factor 1 (EGF1)-like domain.
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Affiliation(s)
- Nicholas C Vanderslice
- Protein Purification and Characterization Laboratories, Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Amanda S Messer
- Protein Purification and Characterization Laboratories, Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; Protein Science Laboratory, UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kanagasabai Vadivel
- Protein Science Laboratory, UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - S Paul Bajaj
- Protein Science Laboratory, UCLA/Orthopaedic Hospital, Department of Orthopaedic Surgery and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Martin Phillips
- UCLA-DOE Biochemistry Instrumentation Facility, Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Mostafa Fatemi
- Protein Purification and Characterization Laboratories, Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Weijie Xu
- Protein Purification and Characterization Laboratories, Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - William H Velander
- Protein Purification and Characterization Laboratories, Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
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Remko M, Broer R, Remková A, Van Duijnen PT. Acidity and metal (Mg 2+ , Ca 2+ , Zn 2+ ) affinity of l -γ-carboxyglutamic acid and its peptide analog. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.09.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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11
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Lew ED, Oh J, Burrola PG, Lax I, Zagórska A, Través PG, Schlessinger J, Lemke G. Differential TAM receptor-ligand-phospholipid interactions delimit differential TAM bioactivities. eLife 2014; 3. [PMID: 25265470 PMCID: PMC4206827 DOI: 10.7554/elife.03385] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 09/28/2014] [Indexed: 12/22/2022] Open
Abstract
The TAM receptor tyrosine kinases Tyro3, Axl, and Mer regulate key features of cellular physiology, yet the differential activities of the TAM ligands Gas6 and Protein S are poorly understood. We have used biochemical and genetic analyses to delineate the rules for TAM receptor–ligand engagement and find that the TAMs segregate into two groups based on ligand specificity, regulation by phosphatidylserine, and function. Tyro3 and Mer are activated by both ligands but only Gas6 activates Axl. Optimal TAM signaling requires coincident TAM ligand engagement of both its receptor and the phospholipid phosphatidylserine (PtdSer): Gas6 lacking its PtdSer-binding ‘Gla domain’ is significantly weakened as a Tyro3/Mer agonist and is inert as an Axl agonist, even though it binds to Axl with wild-type affinity. In two settings of TAM-dependent homeostatic phagocytosis, Mer plays a predominant role while Axl is dispensable, and activation of Mer by Protein S is sufficient to drive phagocytosis. DOI:http://dx.doi.org/10.7554/eLife.03385.001 Cells send out and receive signals to communicate with other cells. Detecting these signals is largely carried out by proteins called receptors that span the cell surface membrane. These proteins typically have extracellular domains outside of the cell that can bind to specific signaling molecules and an intracellular domain inside the cell that relays the information inwards to trigger a response. Three such receptor proteins are collectively known as the TAM receptors. Each day, many billions of cells in the human body die and are engulfed by other cells and broken down so that their building blocks can be reused. TAM receptors are required for this process; and the TAM receptors also help prevent the immune system from going out of control, which would damage the body's own tissues. Two different signaling proteins, called Gas6 and Protein S, can bind to and activate TAM receptors. Both of the signaling proteins can also bind to a phospholipid molecule that is found on the surface membrane of dead cells. However, it is not known if all three TAM receptors bind to both signaling proteins equally, and the importance of the phospholipid-binding domain in the signaling proteins remains unclear. To shed light on the workings of these receptors, Lew et al. created mouse cells that each only express one out of the three TAM receptors. These cells were then exposed to intact Gas6 and Protein S, or shortened versions that lacked the phospholipid-binding domain. Lew et al. found that Gas6 could trigger a response through all three TAM receptors but that Protein S was specific for only two out of the three receptors. Signaling proteins with or without their phospholipid-binding domains bound equally well to the receptors, but the maximum level of response was only triggered when both signaling proteins were intact and the phospholipid molecule was present. This is important since the phospholipid can be thought of as an ‘eat-me’ signal by which the dead cells are recognized by the TAM receptor-expressing cells that will engulf them. Using mice that only produce a TAM receptor called Mer, Lew et al. show that Protein S alone can trigger the process that engulfs and breaks down cells in a living organism. These data and previous work suggest that two TAM receptors—including Mer—are involved in the daily engulfment of dying cells, whereas the third mediates this process during infection and tissue damage. Molecules that inhibit or activate the function of TAM receptors are currently being developed to treat cancer and other diseases. By revealing which receptors respond to which signaling molecules, the findings of Lew et al. will serve to guide these efforts. DOI:http://dx.doi.org/10.7554/eLife.03385.002
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Affiliation(s)
- Erin D Lew
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Jennifer Oh
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Patrick G Burrola
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Irit Lax
- Department of Pharmacology, Yale University School of Medicine, New Haven, United States
| | - Anna Zagórska
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Paqui G Través
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Joseph Schlessinger
- Department of Pharmacology, Yale University School of Medicine, New Haven, United States
| | - Greg Lemke
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
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12
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Vadivel K, Agah S, Messer AS, Cascio D, Bajaj MS, Krishnaswamy S, Esmon CT, Padmanabhan K, Bajaj SP. Structural and functional studies of γ-carboxyglutamic acid domains of factor VIIa and activated Protein C: role of magnesium at physiological calcium. J Mol Biol 2013; 425:1961-1981. [PMID: 23454357 PMCID: PMC4017951 DOI: 10.1016/j.jmb.2013.02.017] [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: 11/21/2012] [Revised: 02/10/2013] [Accepted: 02/14/2013] [Indexed: 11/28/2022]
Abstract
Crystal structures of factor (F) VIIa/soluble tissue factor (TF), obtained under high Mg(2+) (50mM Mg(2+)/5mM Ca(2+)), have three of seven Ca(2+) sites in the γ-carboxyglutamic acid (Gla) domain replaced by Mg(2+) at positions 1, 4, and 7. We now report structures under low Mg(2+) (2.5mM Mg(2+)/5mM Ca(2+)) as well as under high Ca(2+) (5mM Mg(2+)/45 mM Ca(2+)). Under low Mg(2+), four Ca(2+) and three Mg(2+) occupy the same positions as in high-Mg(2+) structures. Conversely, under low Mg(2+), reexamination of the structure of Gla domain of activated Protein C (APC) complexed with soluble endothelial Protein C receptor (sEPCR) has position 4 occupied by Ca(2+) and positions 1 and 7 by Mg(2+). Nonetheless, in direct binding experiments, Mg(2+) replaced three Ca(2+) sites in the unliganded Protein C or APC. Further, the high-Ca(2+) condition was necessary to replace Mg4 in the FVIIa/soluble TF structure. In biological studies, Mg(2+) enhanced phospholipid binding to FVIIa and APC at physiological Ca(2+). Additionally, Mg(2+) potentiated phospholipid-dependent activations of FIX and FX by FVIIa/TF and inactivation of activated factor V by APC. Since APC and FVIIa bind to sEPCR involving similar interactions, we conclude that under the low-Mg(2+) condition, sEPCR binding to APC-Gla (or FVIIa-Gla) replaces Mg4 by Ca4 with an attendant conformational change in the Gla domain ω-loop. Moreover, since phospholipid and sEPCR bind to FVIIa or APC via the ω-loop, we predict that phospholipid binding also induces the functional Ca4 conformation in this loop. Cumulatively, the data illustrate that Mg(2+) and Ca(2+) act in concert to promote coagulation and anticoagulation.
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Affiliation(s)
- Kanagasabai Vadivel
- UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, Los Angeles, CA 90095, USA
| | - Sayeh Agah
- UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, Los Angeles, CA 90095, USA
| | - Amanda S Messer
- UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, Los Angeles, CA 90095, USA
| | - Duilio Cascio
- UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, CA 90095, USA
| | - Madhu S Bajaj
- Division of Pulmonology and Critical Care, Department of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Sriram Krishnaswamy
- Department of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Charles T Esmon
- Oklahoma Medical Research Foundation, Howard Hughes Medical Institute, Oklahoma City, OK 73104, USA
| | - Kaillathe Padmanabhan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - S Paul Bajaj
- UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
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13
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Houde D, Berkowitz SA. Conformational comparability of factor IX-Fc fusion protein, factor IX, and purified Fc fragment in the absence and presence of calcium. J Pharm Sci 2012; 101:1688-700. [PMID: 22271461 DOI: 10.1002/jps.23064] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/29/2011] [Accepted: 01/05/2012] [Indexed: 01/13/2023]
Abstract
A long lasting recombinant factor IX -Fc fusion protein (rFIX-Fc) is being developed for the treatment of hemophilia B and is currently in late stage clinical investigation. By limiting injection frequency and maintaining efficacy, rFIX-Fc shows promise as a new therapeutic option for hemophilia B patients. However, before gaining regulatory approval, rFIX-Fc must undergo rigorous analytical and biological testing, in addition to clinical trials. Included in this testing is the need to understand this protein's higher-order structure and dynamics. In this study, we investigated and compared the biophysical properties of rFIX-Fc, rFIX, and Fc using hydrogen/deuterium exchange mass spectrometry and differential scanning calorimetry. Within the limits of these techniques, our results show that structural comparability exists between rFIX and the FIX region of rFIX-Fc. In addition, changes in the structure and dynamics of both proteins, in response to calcium binding, a requirement for FIX function, are also highly comparable. In the case of Fc and Fc region of rFIX-Fc, conformational comparability is also established. These biophysical results further support the conclusion that fusing an immunoglobulin gamma 1 Fc to rFIX does not significantly alter the higher-order structure of FIX or Fc, Ca binding to FIX, or Fc functionality.
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Affiliation(s)
- Damian Houde
- Analytical Development, Biogen Idec, Cambridge, Massachusetts 02142, USA.
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14
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Li H, Bai S, Wei JY, Berkowitz SA, Brader ML. Calcium binding to a factor ix Fc fusion protein and effects on higher-order structure. J Pharm Sci 2011; 100:4597-606. [PMID: 21678428 DOI: 10.1002/jps.22660] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 05/18/2011] [Accepted: 05/20/2011] [Indexed: 11/10/2022]
Abstract
There is significant scope for more meaningful evaluation of higher-order structure in defining the quality of biopharmaceutical products [Bush L. 2010. Biopharm Int 23(4):14]. We have used isothermal titration calorimetry (ITC) to characterize the Ca(2+) -binding isotherm of a recombinant human factor IX Fc fusion protein (rFIXFc) and the parent recombinant human factor IX molecule (rFIX). Circular dichroism, intrinsic fluorescence, and Fourier transform infrared spectroscopies detected characteristic spectral changes that appear qualitatively consistent with the previously characterized behavior of the factor IX molecule. Sedimentation velocity and dynamic light scattering measurements were recorded in the presence and absence of Ca(2+) over the protein concentration range 1-10 mg/mL. ITC of Ca(2+) binding to rFIXFc reveals a distinctive exothermic-binding isotherm, which is interpreted as consistent with two high-affinity and approximately 14 lower-affinity Ca(2+) sites reported in the literature for human factor IX (Schmidt AE, Bajaj SP. 2003. Trends Cardiovasc Med 13(1):39-45). Analysis of accelerated degradation samples showed significant alterations in Ca(2+) binding, which correlates with significant loss of biopotency and fragmentation by gel chip capillary electrophoresis. Collectively, these data establish a close correspondence in the Ca(2+) -binding characteristics of rFIXFc and its parent rFIX molecule. The utility of ITC to provide a highly pertinent and selective biophysical signature of structure-function for a therapeutic factor protein is discussed.
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Affiliation(s)
- Hao Li
- Department of Protein Pharmaceutical Development, Biogen Idec, San Diego, California 92122, USA
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15
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Arcario MJ, Ohkubo YZ, Tajkhorshid E. Capturing spontaneous partitioning of peripheral proteins using a biphasic membrane-mimetic model. J Phys Chem B 2011; 115:7029-37. [PMID: 21561114 PMCID: PMC3102442 DOI: 10.1021/jp109631y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 04/20/2011] [Indexed: 12/25/2022]
Abstract
Membrane binding of peripheral proteins, mediated by specialized anchoring domains, is a crucial step for their biological function. Computational studies of membrane insertion, however, have proven challenging and largely inaccessible, due to the time scales required for the complete description of the process, mainly caused by the slow diffusion of the lipid molecules composing the membrane. Furthermore, in many cases, the nature of the membrane "anchor", i.e., the part of the protein that inserts into the membrane, is also unknown. Here, we address some of these issues by developing and employing a simplified representation of the membrane by a biphasic solvent model which we demonstrate can be used efficiently to capture and describe the process of hydrophobic insertion of membrane anchoring domains in all-atom molecular dynamics simulations. Applying the model, we have studied the insertion of the anchoring domain of a coagulation protein (the GLA domain of human protein C), starting from multiple initial configurations varying with regard to the initial orientation and height of the protein with respect to the membrane. In addition to efficiently and consistently identifying the "keel" region as the hydrophobic membrane anchor, within a few nanoseconds each configuration simulated showed a convergent height (2.20 ± 1.04 Å) and angle with respect to the interface normal (23.37 ± 12.48°). We demonstrate that the model can produce the same results as those obtained from a full representation of a membrane, in terms of both the depth of penetration and the orientation of the protein in the final membrane-bound form with an order of magnitude decrease in the required computational time compared to previous models, allowing for a more exhaustive search for the correct membrane-bound configuration.
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Affiliation(s)
- Mark J. Arcario
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Y. Zenmei Ohkubo
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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16
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Wu H, Xu X, Zhang L, Shen D, Peng L, Zhang Y, Song J. Mg(II)-induced binding of factor IX-binding protein from the venom of Agkistrodon Halys Pallas with factor Xa. Toxicon 2010; 55:1358-64. [PMID: 20156470 DOI: 10.1016/j.toxicon.2010.02.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 01/30/2010] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
Abstract
Factor IX-binding protein (AHP IX-bp), a Ca2+- and Zn2+-binding protein from the venom of Agkistrodon Halys Pallas was reported to bind specifically with factor IX in a Zn2+-dependent manner. Here we have purified AHP IX-bp by a simple two-step of chromatography procedure and found that AHP IX-bp also binds factor Xa (FXa) with high binding-affinity in a Mg2+-dependent manner. Although Mg2+ ions have a significantly low binding-affinity for apo-AHP IX-bp as determined by isothermal titration calorimetry, they can induce the binding of apo-AHP IX-bp with FXa even in the absence of Ca2+ as determined by native PAGE and surface plasmon resonance. Mg2+ ions are required to maintain in vivo function of FX Gla domain for its recognition of AHP IX-bp. Both Ca2+ and Zn2+ ions fail to induce the binding between apo-AHP IX-bp and FXa. The abundant Mg2+ ions in blood play an important role in the anticoagulation of AHP IX-bp.
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Affiliation(s)
- Hao Wu
- Department of Chemistry, University of Science and Technology of China, No. 96, Jinzhai Road, Hefei 230026, PR China
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17
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Krisinger MJ, Guo LJ, Salvagno GL, Guidi GC, Lippi G, Dahlbäck B. Mouse recombinant protein C variants with enhanced membrane affinity and hyper-anticoagulant activity in mouse plasma. FEBS J 2009; 276:6586-602. [PMID: 19817854 DOI: 10.1111/j.1742-4658.2009.07371.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mouse anticoagulant protein C (461 residues) shares 69% sequence identity with its human ortholog. Interspecies experiments suggest that there is an incompatibility between mouse and human protein C, such that human protein C does not function efficiently in mouse plasma, nor does mouse protein C function efficiently in human plasma. Previously, we described a series of human activated protein C (APC) Gla domain mutants (e.g. QGNSEDY-APC), with enhanced membrane affinity that also served as superior anticoagulants. To characterize these Gla mutants further in mouse models of diseases, the analogous mutations were now made in mouse protein C. In total, seven mutants (mutated at one or more of positions P(10)S(12)D(23)Q(32)N(33)) and wild-type protein C were expressed and purified to homogeneity. In a surface plasmon resonance-based membrane-binding assay, several high affinity protein C mutants were identified. In Ca(2+) titration experiments, the high affinity variants had a significantly reduced (four-fold) Ca(2+) requirement for half-maximum binding. In a tissue factor-initiated thrombin generation assay using mouse plasma, all mouse APC variants, including wild-type, could completely inhibit thrombin generation; however, one of the variants denoted mutant III (P10Q/S12N/D23S/Q32E/N33D) was found to be a 30- to 50-fold better anticoagulant compared to the wild-type protein. This mouse APC variant will be attractive to use in mouse models aiming to elucidate the in vivo effects of APC variants with enhanced anticoagulant activity.
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Affiliation(s)
- Michael J Krisinger
- Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital, Malmö, Sweden
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18
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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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19
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Rajotte I, Hasanbasic I, Blostein M. Gas6-mediated signaling is dependent on the engagement of its gamma-carboxyglutamic acid domain with phosphatidylserine. Biochem Biophys Res Commun 2008; 376:70-3. [PMID: 18760998 DOI: 10.1016/j.bbrc.2008.08.083] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Accepted: 08/19/2008] [Indexed: 11/30/2022]
Abstract
Gas6 is a vitamin K-dependent protein containing gamma-carboxyglutamic acid (Gla) at its N-terminus and a receptor binding domain at its C-terminus. Gas6-Axl binding is necessary but not sufficient to support endothelial cell survival as decarboxylated gas6 inhibits the pro-survival function of gas6 by binding and inhibiting Axl, even though decarboxylated gas6 cannot support endothelial cell survival itself. It is hypothesized that interactions between the Gla domain of gas6 and phosphatidylserine (PS), though not required for gas6 binding to Axl, are necessary for gas6-Axl function. In support of this hypothesis are results showing that (1) two specific inhibitors of Gla-PS interactions, namely soluble PS and Annexin V, abrogate gas6-mediated endothelial cell survival and (2) Soluble PS inhibits Akt activation, a downstream intracellular event triggered by gas6-Axl binding. In conclusion, we propose a heretofore unknown function of Gla, where Gla-PS binding on the N-terminus of gas6 is necessary for a gas6 function mediated through its binding to Axl via its C-terminus.
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Affiliation(s)
- Isabelle Rajotte
- The Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, 3755 Cote Sainte Catherine, Montreal, Que., Canada H3T1E2
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20
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Fischer TH, Wolberg AS, Bode AP, Nichols TC. The interaction of factor VIIa with rehydrated, lyophilized platelets. Platelets 2008; 19:182-91. [PMID: 18432519 DOI: 10.1080/09537100701493794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The experiments presented here were undertaken to determine if factor VIIa (rFVIIa, the Novo Nordisk product NovoSeven) will directly bind to rehydrated, lyophilized (RL) platelets for the formation of a catalytic surface with an enhanced ability to generate thrombin. The interaction between rFVIIa and the RL platelet surface was examined by measuring equilibrium and non-equilibrium binding of the coagulation factor to the cells and by following the effects of the surface modification on the kinetics of thrombin generation. The association of rFVIIa with RL platelets was rapid with saturation occurring within minutes. Disassociation was slow, with over half of the coagulation factor remaining bound after two hours. Densities of over one million molecules of rFVIIa per RL platelet were obtained when high concentrations of rFVIIa were incubated with RL platelets. Thrombin generation measurements showed that RL platelet-bound rFVIIa was catalytically active. Thus we can expect that RL platelets, which have been shown to effectively bind to sites of vascular injury, will localize rFVIIa to wounds for an increase in therapeutic index. These studies indicate that rFVIIa-RL platelets are worthy of preclinical and clinical development as an infusion agent for severe bleeding.
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Affiliation(s)
- Thomas H Fischer
- Francis Owen Blood Research Laboratory, Department of Pathology and Laboratory Medicine, 125 University Lake Dr., University of North Carolina at Chapel Hill, NC 27516, USA.
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21
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Gopinath S, Shikamoto Y, Mizuno H, Kumar P. Snake-venom-derived Factor IX-binding protein specifically blocks the gamma-carboxyglutamic acid-rich-domain-mediated membrane binding of human Factors IX and X. Biochem J 2007; 405:351-7. [PMID: 17407444 PMCID: PMC1904519 DOI: 10.1042/bj20061737] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A potent anticoagulant protein, IX-bp (Factor IX binding protein), has been isolated from the venom of Trimeresurus flavoviridis (habu snake) and is known to bind specifically to the Gla (gamma-carboxyglutamic acid-rich) domain of Factor IX. To evaluate the molecular basis for its anticoagulation activity, we assessed its interactions with various clotting factors. We found that the anticoagulation activity is primarily due to binding to the Gla domains of Factors IX and X, thus preventing these factors from recognizing phosphatidylserine on the plasma membrane. The present study suggests that ligands that bind to the Gla domains of Factors IX and X may have the potential to become novel anticoagulants.
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Affiliation(s)
- Subash C. B. Gopinath
- *Functional Nucleic Acids Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba City 305-8566, Ibaraki, Japan
| | - Yasuo Shikamoto
- †Age Dimension Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba City 305-8566, Ibaraki, Japan
| | - Hiroshi Mizuno
- *Functional Nucleic Acids Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba City 305-8566, Ibaraki, Japan
- ‡VALWAY Technology Center, NEC Soft Co. Ltd, 1-18-7, Shinkiba, Koto-ku, Tokyo 136-8627, Japan
| | - Penmetcha K. R. Kumar
- *Functional Nucleic Acids Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba City 305-8566, Ibaraki, Japan
- To whom correspondence should be addressed (email )
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22
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Abstract
Herein, we describe the design and surface-binding characterization of a de novo designed peptide, JAK1, which undergoes surface-induced folding at the hydroxyapatite (HA)-solution interface. JAK1 is designed to be unstructured in buffered saline solution, yet undergo HA-induced folding that is largely governed by the periodic positioning of gamma-carboxyglutamic acid (Gla) residues within the primary sequence of the peptide. Circular dichroism (CD) spectroscopy and analytical ultracentrifugation indicate that the peptide remains unfolded and monomeric in solution under normal physiological conditions; however, CD spectroscopy indicates that in the presence of hydroxyapatite, the peptide avidly binds to the mineral surface adopting a helical structure. Adsorption isotherms indicate nearly quantitative surface coverage and Kd = 310 nM for the peptide-surface binding event. X-ray photoelectron spectroscopy (XPS) coupled with the adsorption isotherm data suggests that JAK1 binds to HA, forming a self-limiting monolayer. This study demonstrates the feasibility of using HA surfaces to trigger the intramolecular folding of designed peptides and represents the initial stages of defining the design rules that allow HA-induced peptide folding.
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Affiliation(s)
- Lisa A Capriotti
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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23
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Hansson K, Stenflo J. Post-translational modifications in proteins involved in blood coagulation. J Thromb Haemost 2005; 3:2633-48. [PMID: 16129023 DOI: 10.1111/j.1538-7836.2005.01478.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K Hansson
- Department of Clinical Chemistry, Lund University, University Hospital Malmö, Malmö, Sweden.
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24
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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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25
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Preston RJS, Villegas-Mendez A, Sun YH, Hermida J, Simioni P, Philippou H, Dahlbäck B, Lane DA. Selective modulation of protein C affinity for EPCR and phospholipids by Gla domain mutation. FEBS J 2004; 272:97-108. [PMID: 15634335 DOI: 10.1111/j.1432-1033.2004.04401.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Uniquely amongst vitamin K-dependent coagulation proteins, protein C interacts via its Gla domain both with a receptor, the endothelial cell protein C receptor (EPCR), and with phospholipids. We have studied naturally occurring and recombinant protein C Gla domain variants for soluble (s)EPCR binding, cell surface activation to activated protein C (APC) by the thrombin-thrombomodulin complex, and phospholipid dependent factor Va (FVa) inactivation by APC, to establish if these functions are concordant. Wild-type protein C binding to sEPCR was characterized with surface plasmon resonance to have an association rate constant of 5.23 x 10(5) m(-1).s(-1), a dissociation rate constant of 7.61 x 10(-2) s(-1) and equilibrium binding constant (K(D)) of 147 nm. It was activated by thrombin over endothelial cells with a K(m) of 213 nm and once activated to APC, rapidly inactivated FVa. Each of these interactions was dramatically reduced for variants causing gross Gla domain misfolding (R-1L, R-1C, E16D and E26K). Recombinant variants Q32A, V34A and D35A had essentially normal functions. However, R9H and H10Q/S11G/S12N/D23S/Q32E/N33D/H44Y (QGNSEDY) variants had slightly reduced (< twofold) binding to sEPCR, arising from an increased rate of dissociation, and increased K(m) (358 nm for QGNSEDY) for endothelial cell surface activation by thrombin. Interestingly, these variants had greatly reduced (R9H) or greatly enhanced (QGNSEDY) ability to inactivate FVa. Therefore, protein C binding to sEPCR and phospholipids is broadly dependent on correct Gla domain folding, but can be selectively influenced by judicious mutation.
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Affiliation(s)
- Roger J S Preston
- Department of Haematology, Division of Investigative Science, Hammersmith Campus, Imperial College London, UK
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26
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Perera L, Darden TA, Duke RE, Venkateswarlu D, Pedersen LG. Early Unfolding Response of a Stable Protein Domain to Environmental Changes. J Phys Chem A 2004. [DOI: 10.1021/jp048385l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lalith Perera
- High Performance Computing Group, Information Technology Services, CB#3455, and Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, and Laboratory of Quantitative and Computational Biology, National Institute of Environmental Health Science, Research Triangle Park, North Carolina 27709
| | - Thomas A. Darden
- High Performance Computing Group, Information Technology Services, CB#3455, and Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, and Laboratory of Quantitative and Computational Biology, National Institute of Environmental Health Science, Research Triangle Park, North Carolina 27709
| | - Robert E. Duke
- High Performance Computing Group, Information Technology Services, CB#3455, and Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, and Laboratory of Quantitative and Computational Biology, National Institute of Environmental Health Science, Research Triangle Park, North Carolina 27709
| | - Divi Venkateswarlu
- High Performance Computing Group, Information Technology Services, CB#3455, and Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, and Laboratory of Quantitative and Computational Biology, National Institute of Environmental Health Science, Research Triangle Park, North Carolina 27709
| | - Lee G. Pedersen
- High Performance Computing Group, Information Technology Services, CB#3455, and Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, and Laboratory of Quantitative and Computational Biology, National Institute of Environmental Health Science, Research Triangle Park, North Carolina 27709
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27
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Grant MA, Hansson K, Furie BC, Furie B, Stenflo J, Rigby AC. The Metal-free and Calcium-bound Structures of a γ-Carboxyglutamic Acid-containing Contryphan from Conus marmoreus, Glacontryphan-M. J Biol Chem 2004; 279:32464-73. [PMID: 15155731 DOI: 10.1074/jbc.m313826200] [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
Glacontryphan-M, a novel calcium-dependent inhibitor of L-type voltage-gated Ca(2+) channels expressed in mouse pancreatic beta-cells, was recently isolated from the venom of the cone snail Conus marmoreus (Hansson, K., Ma, X., Eliasson, L., Czerwiec, E., Furie, B., Furie, B. C., Rorsman, P., and Stenflo, J. (2004) J. Biol. Chem. 278, 32453-32463). The conserved disulfide-bonded loop of the contryphan family of conotoxins including a D-Trp is present; however, unique to glacontryphan-M is a histidine within the intercysteine-loop and two gamma-carboxyglutamic acid (Gla) residues, formed by post-translational modification of glutamic acid. The two calcium-binding Gla residues are located in a four residue N-terminal extension of this contryphan. To better understand the structural and functional significance of these residues, we have determined the structure of glacontryphan-M using two-dimensional (1)H NMR spectroscopy in the absence and presence of calcium. Comparisons of the glacontryphan-M structures reveal that calcium binding induces structural perturbations within the Gla-containing N terminus and the Cys(11)-Cys(5)-Pro(6) region of the intercysteine loop. The backbone of N-terminal residues perturbed by calcium, Gla(2) and Ser(3), moves away from the His(8) and Trp(10) aromatic rings and the alignment of the D-Trp(7) and His(8) aromatic rings with respect to the Trp(10) rings is altered. The blockage of L-type voltage-gated Ca(2+) channel currents by glacontryphan-M requires calcium binding to N-terminal Gla residues, where presumably histidine and tryptophan may be accessible for interaction with the channel. The backbone C alpha conformation of the intercysteine loop of calcium-bound glacontryphan-M superimposes on known structures of contryphan-R and Vn (0.83 and 0.66 A, respectively). Taken together these data identify that glacontryphan-M possesses the canonical contryphan intercysteine loop structure, yet possesses critical determinants necessary for a calcium-induced functionally required conformation.
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Affiliation(s)
- Marianne A Grant
- Center for Hemostasis, Thrombosis, and Vascular Biology, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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Huang M, Furie BC, Furie B. Crystal Structure of the Calcium-stabilized Human Factor IX Gla Domain Bound to a Conformation-specific Anti-factor IX Antibody. J Biol Chem 2004; 279:14338-46. [PMID: 14722079 DOI: 10.1074/jbc.m314011200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The binding of Factor IX to membranes during blood coagulation is mediated by the N-terminal gamma-carboxyglutamic acid-rich (Gla) domain, a membrane-anchoring domain found on vitamin K-dependent blood coagulation and regulatory proteins. Conformation-specific anti-Factor IX antibodies are directed at the calcium-stabilized Gla domain and interfere with Factor IX-membrane interaction. One such antibody, 10C12, recognizes the calcium-stabilized form of the Gla domain of Factor IX. We prepared the fully carboxylated Gla domain of Factor IX by solid phase peptide synthesis and crystallized Factor IX-(1-47) in complex with Fab fragments of the 10C12 antibody. The overall structure of the Gla domain in the Factor IX-(1-47)-antibody complex at 2.2 A is similar to the structure of the Factor IX Gla domain in the presence of calcium ions as determined by NMR spectroscopy (Freedman, S. J., Furie, B. C., Furie, B., and Baleja, J. D. (1995) Biochemistry 34, 12126-12137) and by x-ray crystallography (Shikamoto, Y., Morita, T., Fujimoto, Z., and Mizuno, H. (2003) J. Biol. Chem. 278, 24090-24094). The complex structure shows that the complementarity determining region loops of the 10C12 antibody form a hydrophobic pocket to accommodate the hydrophobic patch of the Gla domain consisting of Leu-6, Phe-9, and Val-10. Polar interactions also play an important role in the antibody-antigen recognition. Furthermore, the calcium coordination network of the Factor IX Gla domain is different than in Gla domain structures of other vitamin K-dependent proteins. We conclude that this antibody is directed at the membrane binding site in the omega loop of Factor IX and blocks Factor IX function by inhibiting its interaction with membranes.
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Affiliation(s)
- Mingdong Huang
- Center for Hemostasis, Thrombosis and Vascular Biology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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29
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Deguchi H, Yegneswaran S, Griffin JH. Sphingolipids as Bioactive Regulators of Thrombin Generation. J Biol Chem 2004; 279:12036-42. [PMID: 14722105 DOI: 10.1074/jbc.m302531200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sphingolipids contribute to modulation of two opposing cell processes, cell growth and apoptotic cell death; ceramide and sphingosine promote the latter and sphingosine-1-phosphate triggers the former. Thrombin, a pro-inflammatory protease that is regulated by the blood coagulation cascade, exerts similar effects depending on cell type. Here we report a new mechanism for cross-talk between sphingolipid metabolism and thrombin generation. Sphingosine and sphinganine, but not ceramide or sphingosine-1-phosphate, down-regulated thrombin generation on platelet surfaces (IC(50) = 2.4 and 1.4 microm for sphingosine and sphinganine, respectively) as well as in whole plasma clotting assays. Thrombin generation was also inhibited by glucosylsphingosine, lysosphingomyelin, phytosphingosine, and primary alkylamines with >10 carbons. Acylation of the amino group ablated anticoagulant activities. Factor Va was required for the anticoagulant property of sphingosine because prothrombin activation was inhibited by sphingosine, sphinganine, and stearylamine in the presence but not in the absence of factor Va. Sphingosine did not inhibit thrombin generation when Gla-domainless factor Xa was used in prothrombinase assays, whereas sphingosine inhibited activation of Gla-domainless prothrombin by factor Xa/factor Va in the absence of phospholipids (IC(50) = 0.49 microm). Fluorescence spectroscopy studies showed that sphingosine binds to fluorescein-labeled factor Xa and that this interaction required the Gla domain. These results imply that sphingosine disrupts interactions between factor Va and the Gla domain of factor Xa in the prothrombinase complex. Thus, certain sphingolipids may be bioactive lipid mediators of thrombin generation such that certain sphingolipid metabolites may modulate proteases that affect cell growth and death, blood coagulation, and inflammation.
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Affiliation(s)
- Hiroshi Deguchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, MEM 180, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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30
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Huang M, Rigby AC, Morelli X, Grant MA, Huang G, Furie B, Seaton B, Furie BC. Structural basis of membrane binding by Gla domains of vitamin K-dependent proteins. Nat Struct Mol Biol 2003; 10:751-6. [PMID: 12923575 DOI: 10.1038/nsb971] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2003] [Accepted: 07/24/2003] [Indexed: 11/09/2022]
Abstract
In a calcium-dependent interaction critical for blood coagulation, vitamin K-dependent blood coagulation proteins bind cell membranes containing phosphatidylserine via gamma-carboxyglutamic acid-rich (Gla) domains. Gla domain-mediated protein-membrane interaction is required for generation of thrombin, the terminal enzyme in the coagulation cascade, on a physiologic time scale. We determined by X-ray crystallography and NMR spectroscopy the lysophosphatidylserine-binding site in the bovine prothrombin Gla domain. The serine head group binds Gla domain-bound calcium ions and Gla residues 17 and 21, fixed elements of the Gla domain fold, predicting the structural basis for phosphatidylserine specificity among Gla domains. Gla domains provide a unique mechanism for protein-phospholipid membrane interaction. Increasingly Gla domains are being identified in proteins unrelated to blood coagulation. Thus, this membrane-binding mechanism may be important in other physiologic processes.
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Affiliation(s)
- Mingdong Huang
- Center for Hemostasis and Thrombosis Research, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, 330 Brookline Avenue, Boston, Massachusetts 02215, USA
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31
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Blostein MD, Furie BC, Rajotte I, Furie B. The Gla domain of factor IXa binds to factor VIIIa in the tenase complex. J Biol Chem 2003; 278:31297-302. [PMID: 12782629 DOI: 10.1074/jbc.m302840200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During blood coagulation factor IXa binds to factor VIIIa on phospholipid membranes to form an enzymatic complex, the tenase complex. To test whether there is a protein-protein contact site between the gamma-carboxyglutamic acid (Gla) domain of factor IXa and factor VIIIa, we demonstrated that an antibody to the Gla domain of factor IXa inhibited factor VIIIa-dependent factor IXa activity, suggesting an interaction of the factor IXa Gla domain with factor VIIIa. To study this interaction, we synthesized three analogs of the factor IXa Gla domain (FIX1-47) with Phe-9, Phe-25, or Val-46 replaced, respectively, with benzoylphenylalanine (BPA), a photoactivatable cross-linking reagent. These factor IX Gla domain analogs maintain native tertiary structure, as demonstrated by calcium-induced fluorescence quenching and phospholipid binding studies. In the absence of phospholipid membranes, FIX1-47 was able to inhibit factor IXa activity. This inhibition is dependent on the presence of factor VIIIa, suggesting a contact site between the factor IXa Gla domain and factor VIIIa. To demonstrate a direct interaction we did cross-linking experiments with FIX1-479BPA, FIX1-4725BPA, and FIX1-4746BPA. Covalent cross-linking to factor VIIIa was observed primarily with FIX1-4725BPA and to a much lesser degree with FIX1-4746BPA. Immunoprecipitation experiments with an antibody to the C2 domain of factor VIIIa indicate that the factor IX Gla domain cross-links to the A3-C1-C2 domain of factor VIIIa. These results suggest that the factor IXa Gla domain contacts factor VIIIa in the tenase complex through a contact site that includes phenylalanine 25 and perhaps valine 46.
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Affiliation(s)
- Mark D Blostein
- The Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1A4, Canada.
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32
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Dowd TL, Rosen JF, Li L, Gundberg CM. The three-dimensional structure of bovine calcium ion-bound osteocalcin using 1H NMR spectroscopy. Biochemistry 2003; 42:7769-79. [PMID: 12820886 PMCID: PMC4517610 DOI: 10.1021/bi034470s] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Structural information on osteocalcin or other noncollagenous bone proteins is very limited. We have solved the three-dimensional structure of calcium bound osteocalcin using (1)H 2D NMR techniques and proposed a mechanism for mineral binding. The protons in the 49 amino acid sequence were assigned using standard two-dimensional homonuclear NMR experiments. Distance constraints, dihedral angle constraints, hydrogen bonds, and (1)H and (13)C chemical shifts were all used to calculate a family of 13 structures. The tertiary structure of the protein consisted of an unstructured N terminus and a C-terminal loop (residues 16-49) formed by long-range hydrophobic interactions. Elements of secondary structure within residues 16-49 include type III turns (residues 20-25) and two alpha-helical regions (residues 27-35 and 41-44). The three Gla residues project from the same face of the helical turns and are surface exposed. The genetic algorithm-molecular dynamics simulation approach was used to place three calcium atoms on the NMR-derived structure. One calcium atom was coordinated by three side chain oxygen atoms, two from Asp30, and one from Gla24. The second calcium atom was coordinated to four oxygen atoms, two from the side chain in Gla 24, and two from the side chain of Gla 21. The third calcium atom was coordinated to two oxygen atoms of the side chain of Gla17. The best correlation of the distances between the uncoordinated Gla oxygen atoms is with the intercalcium distance of 9.43 A in hydroxyapatite. The structure may provide further insight into the function of osteocalcin.
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Affiliation(s)
- T L Dowd
- Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York 10467, USA.
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33
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Shikamoto Y, Morita T, Fujimoto Z, Mizuno H. Crystal structure of Mg2+- and Ca2+-bound Gla domain of factor IX complexed with binding protein. J Biol Chem 2003; 278:24090-4. [PMID: 12695512 DOI: 10.1074/jbc.m300650200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Factor IX is an indispensable protein required in the blood coagulation cascade. It binds to the surface of phospholipid membrane by means of a gamma-carboxyglutamic acid (Gla) domain situated at the N terminus. Recently, we showed that physiological concentrations of Mg2+ ions affect the native conformation of the Gla domain and in doing so augment the biological activity of factor IXa and binding affinity with its binding protein even in the presence of Ca2+ ions. Here we report on the crystal structures of the Mg2+/Ca2+-bound and Ca2+-bound (Mg2+-free) factor IX Gla domain (IXGD1-46) in complex with its binding protein (IX-bp) at 1.55 and 1.80 A resolutions, respectively. Three Mg2+ and five Ca2+ ions were bound in the Mg2+/Ca2+-bound IXGD1-46, and the Mg2+ ions were replaced by Ca2+ ions in Mg2+-free IXGD1-46. Comparison of Mg2+/Ca2+-bound with Ca2+-bound structures of the complexes showed that Mg2+ ion, which formed a bridge between IXGD1-46 and IX-bp, forced IXGD1-46 to rotate 4 degrees relative to IX-bp and hence might be the cause of a more tight interaction between the molecules than in the case of the Mg2+-free structure. The results clearly suggest that Mg2+ ions are required to maintain native conformation and in vivo function of factor IX Gla domain during blood coagulation.
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Affiliation(s)
- Yasuo Shikamoto
- Department of Biochemistry, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki 305-8602, Japan
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34
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Rezende SM, Lane DA, Mille-Baker B, Samama MM, Conard J, Simmonds RE. Protein S Gla-domain mutations causing impaired Ca(2+)-induced phospholipid binding and severe functional protein S deficiency. Blood 2002; 100:2812-9. [PMID: 12351389 DOI: 10.1182/blood-2002-03-0909] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have identified 2 PROS1 missense mutations in the exon that encodes the vitamin K-dependent Gla domain of protein S (Gly11Asp and Thr37Met) in kindred with phenotypic protein S deficiency and thrombosis. In studies using recombinant proteins, substitution of Gly11Asp did not affect production of protein S but resulted in 15.2-fold reduced protein S activity in a factor Va inactivation assay. Substitution of Thr37Met reduced expression by 33.2% (P <.001) and activity by 3.6-fold. The Gly11Asp variant had 5.4-fold reduced affinity for anionic phospholipid vesicles (P <.0001) and decreased affinity for an antibody specific for the Ca(2+)-dependent conformation of the protein S Gla domain (HPS21). Examination of a molecular model suggested that this could be due to repositioning of Gla29. In contrast, the Thr37Met variant had only a modest 1.5-fold (P <.001), reduced affinities for phospholipid and HPS21. This mutation seems to disrupt the aromatic stack region. The proposita was a compound heterozygote with free protein S antigen levels just below the lower limit of the normal range, and this is now attributed to the partial expression defect of the Thr37Met mutation. The activity levels were strongly reduced to 15% of normal, probably reflecting the functional deficit of both protein S variants. Her son (who was heterozygous only for Thr37Met) had borderline levels of protein S antigen and activity, reflecting the partial secretion and functional defect associated with this mutation. This first characterization of natural protein S Gla-domain variants highlights the importance of the high affinity protein S-phospholipid interaction for its anticoagulant role.
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Affiliation(s)
- Suely M Rezende
- Department of Haematology, Division of Investigative Science, Hammersmith Campus, Imperial College of Science, Technology, and Medicine, London, United Kingdom
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35
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Refino CJ, Jeet S, DeGuzman L, Bunting S, Kirchhofer D. A human antibody that inhibits factor IX/IXa function potently inhibits arterial thrombosis without increasing bleeding. Arterioscler Thromb Vasc Biol 2002; 22:517-22. [PMID: 11884300 DOI: 10.1161/hq0302.105375] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
10C12, a human antibody F(ab')2, which specifically binds to the gamma-carboxyglutamic acid domain of factor IX/factor IXa (F.IX/IXa), interferes with all known coagulation processes in which F.IX/IXa is involved. In a rabbit model of carotid artery injury, intravenous administration of 10C12 or heparin decreased thrombosis dose dependently. The dose that resulted in a 90% reduction of thrombus mass (ED90) was a 30-microg/kg bolus of 10C12 or a 100-U/kg bolus plus 1.0 U x kg(-1) x min(-1) infusion of heparin. Heparin, at and below the ED90, significantly prolonged coagulation times and cuticle bleeding times. In contrast, 10C12 had no effect on coagulation or bleeding times at doses up to 4 times the ED90. To further evaluate the effect of 10C12 on bleeding, it was compared with heparin in a novel model of blood loss. At the ED90 of heparin, blood loss induced by a standardized injury to the vasculature of the rabbit tibia increased to more than 2 times that of saline controls. In contrast, the dose of 10C12 required to produce a similar increase in blood loss was more than 30 times the ED90. The antithrombotic potency and relative safety of this fully human antibody suggests that it may have therapeutic value for treatment of thrombotic disorders.
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Affiliation(s)
- Canio J Refino
- Department of Physiology, Genentech Inc, South San Francisco, Calif 94080, USA.
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36
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Falls LA, Furie BC, Jacobs M, Furie B, Rigby AC. The omega-loop region of the human prothrombin gamma-carboxyglutamic acid domain penetrates anionic phospholipid membranes. J Biol Chem 2001; 276:23895-902. [PMID: 11312259 DOI: 10.1074/jbc.m008332200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hydrophobic omega-loop within the prothrombin gamma-carboxyglutamic acid-rich (Gla) domain is important in membrane binding. The role of this region in membrane binding was investigated using a synthetic peptide, PT-(1-46)F4W, which includes the N-terminal 46 residues of human prothrombin with Phe-4 replaced by Trp providing a fluorescent probe. PT-(1-46)F4W and PT-(1-46) bind calcium ions and phospholipid membranes, and inhibit the prothrombinase complex. PT-(1-46)F4W, but not PT-(1-46), exhibits a blue shift (5 nm) and red-edge excitation shift (28 nm) in the presence of phosphatidylserine (PS)-containing vesicles, suggesting Trp-4 is located within the motionally restricted membrane interfacial region. PS-containing vesicles protect PT-(1-46)F4W, but not PT-(1-46), fluorescence from potassium iodide-induced quenching. Stern-Volmer analysis of the quenching of PT-(1-46)F4W in the presence and absence of 80% phosphatidylcholine/20% PS vesicles suggested that Trp-4 is positioned within the membrane and protected from aqueous quenching agents whereas Trp-41 remains solvent-accessible in the presence of PS-containing vesicles. Fluorescence quenching of membrane-bound PT-(1-46)F4W is optimal with 7- and 10-doxyl-labeled lipids, indicating that Trp-4 is inserted 5 to 7 A into the bilayer. This report demonstrates that the omega-loop region of prothrombin specifically interacts with PS-containing membranes within the interfacial membrane region.
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Affiliation(s)
- L A Falls
- Division of Hemostasis and Thrombosis Research, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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37
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Mizuno H, Fujimoto Z, Atoda H, Morita T. Crystal structure of an anticoagulant protein in complex with the Gla domain of factor X. Proc Natl Acad Sci U S A 2001; 98:7230-4. [PMID: 11404471 PMCID: PMC34651 DOI: 10.1073/pnas.131179698] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2000] [Accepted: 04/11/2001] [Indexed: 11/18/2022] Open
Abstract
The gamma-carboxyglutamic acid (Gla) domain of blood coagulation factors is responsible for Ca2+-dependent phospholipid membrane binding. Factor X-binding protein (X-bp), an anticoagulant protein from snake venom, specifically binds to the Gla domain of factor X. The crystal structure of X-bp in complex with the Gla domain peptide of factor X at 2.3-A resolution showed that the anticoagulation is based on the fact that two patches of the Gla domain essential for membrane binding are buried in the complex formation. The Gla domain thus is expected to be a new target of anticoagulant drugs, and X-bp provides a basis for designing them. This structure also provides a membrane-bound model of factor X.
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Affiliation(s)
- H Mizuno
- Department of Biotechnology, National Institute of Agrobiological Resources, Tsukuba, Ibaraki 305-8602, Japan.
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38
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Walker CS, Shetty RP, Clark K, Kazuko SG, Letsou A, Olivera BM, Bandyopadhyay PK. On a potential global role for vitamin K-dependent gamma-carboxylation in animal systems. Evidence for a gamma-glutamyl carboxylase in Drosophila. J Biol Chem 2001; 276:7769-74. [PMID: 11110799 DOI: 10.1074/jbc.m009576200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vitamin K-dependent gamma-carboxylation of glutamate to gamma-carboxyglutamate was originally well characterized in the mammalian blood clotting cascade. gamma-Carboxyglutamate has also been found in a number of other mammalian proteins and in neuropeptides from the venoms of marine snails belonging to the genus Conus, suggesting wider prevalence of gamma-carboxylation. We demonstrate that an open reading frame from a Drosophila melanogaster cDNA clone encodes a protein with vitamin K-dependent gamma-carboxylase activity. The open reading frame, 670 amino acids in length, is truncated at the C-terminal end compared with mammalian gamma-carboxylase, which is 758 amino acids. The mammalian gene has 14 introns; in Drosophila there are two much shorter introns but in positions precisely homologous to two of the mammalian introns. In addition, a deletion of 6 nucleotides is observed when cDNA and genomic sequences are compared. In situ hybridization to fixed embryos indicated ubiquitous presence of carboxylase mRNA throughout embryogenesis. Northern blot analysis revealed increased mRNA levels in 12-24-h embryos. The continued presence of carboxylase mRNA suggests that it plays an important role during embryogenesis. Although the model substrate FLEEL is carboxylated by the enzyme, a substrate containing the propeptide of a Conus carboxylase substrate, conantokin G, is poorly carboxylated. Its occurrence in vertebrates, molluscan systems (i.e. Conus), and Drosophila and the apparently strong homology between the three systems suggest that this is a highly conserved and widely distributed post-translational modification in biological systems.
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Affiliation(s)
- C S Walker
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
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39
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Metzler DE, Metzler CM, Sauke DJ. Transferring Groups by Displacement Reactions. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50015-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Baleja JD. Structure determination of membrane-associated proteins from nuclear magnetic resonance data. Anal Biochem 2001; 288:1-15. [PMID: 11141300 DOI: 10.1006/abio.2000.4815] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This Review covers the delineation and optimization of protein-lipid systems for study using solution-state NMR spectroscopy. The first half presents the necessary background for a membrane protein biochemist to initiate collaboration with an NMR spectroscopist. The second half provides guidelines for the spectroscopist on data collection, analysis for obtaining conformational information, and structure generation and assessment. Although the emphasis is on the study of peptides in detergent micelles, methods are outlined for larger membrane-associated proteins and for use of other solubilizing agents.
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Affiliation(s)
- J D Baleja
- Department of Biochemistry, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts, 02111, USA
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41
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Hackeng TM, Fernández JA, Dawson PE, Kent SB, Griffin JH. Chemical synthesis and spontaneous folding of a multidomain protein: anticoagulant microprotein S. Proc Natl Acad Sci U S A 2000; 97:14074-8. [PMID: 11106381 PMCID: PMC18873 DOI: 10.1073/pnas.260239797] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Because of recent high-yield native ligation techniques, chemical synthesis of larger multidomain bioactive proteins is rapidly coming within reach. Here we describe the total chemical synthesis of a designed "microprotein S," comprising the gamma-carboxyglutamic acid-rich module, the thrombin-sensitive module, and the first epidermal growth factor-like module of human plasma protein S (residues 1-116). Synthetic microprotein S expressed anticoagulant cofactor activity for activated protein C in the down-regulation of blood coagulation, and the anticoagulant activity of microprotein S was not neutralized by C4b-binding protein, a natural inhibitor of native protein S in plasma. The correct folding of this complex multidomain protein was enhanced compared with individual modules because the gamma-carboxyglutamic acid-rich module and the thrombin-sensitive module markedly facilitated correct folding of the first epidermal growth factor-like module compared with folding of the first epidermal growth factor-like module alone. These results demonstrate that total chemical synthesis of proteins offers an effective way to generate multidomain biologically active proteins.
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Affiliation(s)
- T M Hackeng
- Department of Molecular and Experimental Medicine, Skaggs Institute for Chemical Biology, La Jolla, CA 92037, USA.
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42
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Dodojacek R, Höfler G, Leschnik B, Muntean W. A novel type of mutation at the propeptide cleavage site (AlA+1Thr) causing symptomatic protein C type II deficiency. Thromb Res 2000; 100:109-13. [PMID: 11053623 DOI: 10.1016/s0049-3848(00)00291-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- R Dodojacek
- Department of Paediatrics, and Ludwig Boltzmann Research Institute for Paediatric Haemostasis and Thrombosis, University of Graz, Austria
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43
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Abstract
Vitamin K is required for the synthesis of gamma-carboxyglutamate (Gla) during postribosomal protein modification. Substrates include blood clotting proteins, bone proteins, cell signaling, and receptor proteins. In addition, Gla is a component of short toxin peptides from the marine snail Conus. Studies of structure-function relationships are the most advanced for the blood coagulation proteins. Reviews of vitamin K action and blood coagulation are presented. Special focus is on the structure-function role of Gla in blood coagulation and the impact of this amino acid on enzyme reaction kinetics. This amino acid forms calcium and membrane binding sites for these proteins. Two proposed mechanisms of protein-membrane attachment are reviewed. One involves membrane attachment by protein insertion into the hydrocarbon region of the membrane, while another considers attachment by specific interactions with phospholipid head groups. Membrane attachment generates the potential for several forms of nonclassical enzyme kinetic behaviors, all of which have been observed in vitro. For example, the reaction may be limited by properties of the enzyme active site, a condition that allows use of classic steady-state enzyme kinetic parameters. However, the reaction may be limited by substrate binding to the membrane, by substrate flux through solution, and/or by solvent flow rates across the membrane surface. These states provide special mechanisms that are not anticipated by classical steady-state kinetic derivations. They may be used to regulate coagulation in vivo. Overall, vitamin K research spans the spectrum of biological research and experience. Exciting new ideas and findings continue to emanate from vitamin K-related research.
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Affiliation(s)
- G L Nelsestuen
- Department of Biochemistry, University of Minnesota, St. Paul 55108, USA
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McGee MP, Teuschler H, Liang J. Electrostatic interactions during activation of coagulation factor IX via the tissue factor pathway: effect of univalent salts. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1453:239-53. [PMID: 10036322 DOI: 10.1016/s0925-4439(98)00108-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Interaction between the Gla-domain of coagulation proteins and negatively charged phospholipid membranes is essential for blood coagulation reactions. The interaction is calcium-dependent and mediated both by electrostatic and hydrophobic forces. This report focuses on the electrostatic component of factor IX activation via the extrinsic pathway. Effective charges during the reaction are measured by ionic titration of activity, according to the Debye-Huckel and Gouy-Chapman models. Rates of activation decrease with ionic strength independently of the type of monovalent salt used to control ionic strength. Moreover, the effect of ionic strength decreases at concentrations of charged phospholipid approaching saturation levels, indicating that membrane charges participate directly in the ionic interaction measured. The effective charge on calcium-bound factor IX during activation on phospholipid membranes is 0.95+/-0.1. Possible sites mediating contacts between the Gla-domain and membranes are selected by geometrical criteria in several metal-bound Gla-domain structures. A pocket with a solvent opening-pore of area 24-38 A2 is found in the Gla-domain of factors IX, VII, and prothrombin. The pocket contains atoms with negative partial charges, including carboxylate oxygens from Gla residues, and has a volume of 57-114 A3, sufficient to accommodate additional calcium atoms. These studies demonstrate that electrostatic forces modify the activity coefficient of factor IX during functional interactions and suggest a conserved pocket motif as the contact site between the calcium-bound Gla-domain and charged membranes.
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Affiliation(s)
- M P McGee
- Medicine Department, Rheumatology Section, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA
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Zwaal RF, Comfurius P, Bevers EM. Lipid-protein interactions in blood coagulation. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1376:433-53. [PMID: 9805008 DOI: 10.1016/s0304-4157(98)00018-5] [Citation(s) in RCA: 203] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has long been appreciated that lipids, particularly anionic phospholipids, promote blood coagulation. The last two decades have seen an increasing insight into the kinetic and mechanistic aspects regarding the mode of action of phospholipids in blood coagulation. This essay attempts to review these developments with particular emphasis on the structure of lipid-binding domains of blood coagulation proteins, and the variable effect of phospholipid composition on the interaction with these proteins. Some examples are discussed of how lipid membranes direct the pathway of enzymatic conversions in blood coagulation complexes, also illustrating that the membrane lipid surface is more than an inert platform for the assembly of coagulation factors. Finally, the controlled exposure of procoagulant lipid on the surface of blood cells is shortly reviewed, and an example is discussed of how interference with lipid-protein interactions in blood coagulation may result in pathological phenomena.
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Affiliation(s)
- R F Zwaal
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, P.O. Box 616, 6200 MD Maastricht, Netherlands
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Romero EE, Velazquez-Estades LJ, Deo R, Schapiro B, Roth DA. Cloning of rat vitamin K-dependent gamma-glutamyl carboxylase and developmentally regulated gene expression in postimplantation embryos. Exp Cell Res 1998; 243:334-46. [PMID: 9743593 DOI: 10.1006/excr.1998.4151] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vitamin K-dependent carboxylase catalyzes the posttranslational modification of glutamate to gamma-carboxyglutamate (Gla) in its substrates, the vitamin K-dependent proteins (VKDPs). This modification is required for the activities of the VKDPs. Recent evidence demonstrates previously unrecognized roles for VKDPs as signaling molecules important in the regulation of cell growth, adhesion, and apoptosis, suggesting developmental functions for VKDPs and hence the carboxylase. The tissue distribution and functions of carboxylase in development are unknown. In this study, we isolated and characterized the full-length cDNA encoding the rat carboxylase and analyzed, at the cellular level, the expression of this gene in rat embryos by in situ hybridization. We demonstrate that the expression of this gene is highly regulated in a developmental and tissue-specific manner. Hepatocytes, the major site of synthesis of VKDPs of blood coagulation, express carboxylase mRNA late in gestation, in contrast to the central nervous system, mesenchymal, and skeletal tissues which express carboxylase mRNA early during rat embryogenesis. The tissue-specific temporal expression of the carboxylase gene during embryogenesis indicates that vitamin K-dependent carboxylation and the formation of Gla is developmentally regulated. These studies suggest that vitamin K-dependent carboxylation is an important modulator of embryonic VKDP function.
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Affiliation(s)
- E E Romero
- Division of Hematology-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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Veeraraghavan S, Baleja JD, Gilbert GE. Structure and topography of the membrane-binding C2 domain of factor VIII in the presence of dodecylphosphocholine micelles. Biochem J 1998; 332 ( Pt 2):549-55. [PMID: 9601086 PMCID: PMC1219512 DOI: 10.1042/bj3320549] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A 21 residue peptide from the C2 domain of the antihaemophilic factor VIII competes with factor VIII for membrane-binding sites in vitro. Here, we provide the structure and topography of the peptide in solution, on dodecylphosphocholine (DPC) micelles, determined using 1H-NMR spectroscopy. The peptide assumes an amphipathic structure comprising an extended N-terminal region and a C-terminal helix. The average root-mean-square deviation is 0.7+/-0.2 A for the superimposition of the backbone atoms of Ile6 to Arg18 on the lowest energy structure. Whereas the backbone conformation is similar to that in SDS micelles, the Trp11 side-chain orientation is dramatically changed. The indole ring is nearly parallel to the peptide backbone in SDS micelles but perpendicular in DPC micelles. Further, pKa values of the two histidines change by more than 1 pH unit in SDS relative to DPC, which localizes the imidazole rings to the interfacial region. Line-broadening induced by spin-labelled phosphatidylcholine shows that most of the amino acid side-chains that penetrate the DPC micelle are hydrophobic. Thus, the long axis of the peptide lies parallel to the micelle surface and the hydrophobic face of the alpha-helix provides hydrophobic membrane interaction. The large chemical shift changes shown by Trp11 and N-terminal amino acid residues in SDS relative to DPC indicate that this region may be involved in membrane phospholipid recognition. 1H-NMR assignments, CD spectra, one-dimensional 1H-NMR spectra, chemical-shift analysis and nuclear Overhauser effect information are reported in Supplementary Publication SUP 50184 (11 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K, from whom copies can be obtained according to the terms indicated in Biochem. J. (1997) 321, 8.
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Affiliation(s)
- S Veeraraghavan
- Department of Biochemistry, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA
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Roy RS, Kim S, Baleja JD, Walsh CT. Role of the microcin B17 propeptide in substrate recognition: solution structure and mutational analysis of McbA1-26. CHEMISTRY & BIOLOGY 1998; 5:217-28. [PMID: 9545435 DOI: 10.1016/s1074-5521(98)90635-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The peptide antibiotic microcin B17 (MccB17) contains oxazole and thiazole heterocycles formed by the post-translational modification of four cysteine and four serine residues. An amino-terminal propeptide targets the 69 amino acid precursor of MccB17 (preproMccB17) to the heterocyclization enzyme MccB17 synthetase. The mode of synthetase recognition has been unclear, because there has been limited structural information available on the MccB17 propeptide to date. RESULTS The solution structure of the MccB17 propeptide (McbA1-26), determined using nuclear magnetic resonance, reveals that McbA1-26 is an amphipathic alpha helix. Mutational analysis of 13 propeptide residues showed that Phe8 and Leu12 are essential residues for MccB17 synthetase recognition. A domain of the propeptide was putatively identified as the region that interacts with the synthetase. CONCLUSIONS MccB17 synthetase recognizes key hydrophobic residues within a helical propeptide, allowing the selective heterocyclization of downstream cysteine and serine residues in preproMccB17. The determination of the solution structure of the propeptide should facilitate the investigation of other functions of the propeptide, including a potential role in antibiotic secretion.
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Affiliation(s)
- R S Roy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Wojcik EG, Cheung WF, van den Berg M, van der Linden IK, Stafford DW, Bertina RM. Identification of residues in the Gla-domain of human factor IX involved in the binding to conformation specific antibodies. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1382:91-101. [PMID: 9507074 DOI: 10.1016/s0167-4838(97)00149-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The binding of Ca2+ induces a conformational change in factor IX which can be monitored with conformation specific antibodies. Anti-FIX:Mg(II) antibodies recognize a conformational epitope (FIX') that can be induced by several metal ions such as Ca2+, Mg2+, Mn2+ and Ba2+, while anti-FIX:Ca(II) antibodies recognize a conformational epitope (FIX*) that can be only induced by Ca2+ and Sr2+ ions (Liebman et al., J. Biol. Chem., vol. 262 (1987) pp. 7605-7612). The latter conformation is essential for the function of factor IX. In this study we tried to identify residues in the Gla-domain of factor IX which are involved in binding to anti-factor IX:Mg(II) and anti-factor IX:Ca(II) antibodies. For this we substituted residues in recombinant human factor IX for those of factor X or factor VII. The substitution of residues 1-40 of factor IX by those of factor VII eliminated binding to both types of antibodies. Re-introduction of factor IX specific residues increased the binding to conformation specific anti-factor IX antibodies, but reduced the binding to conformation specific anti-factor VII antibodies, indicating that the structural integrity of the Gla-domain was not seriously affected by the mutations. We provide evidence that residues 33, 39 and 40 of human factor IX are important for binding to anti-factor IX:Mg(II) antibodies, while residues 1-11 are important for binding to anti-factor IX:Ca(II) antibodies.
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Affiliation(s)
- E G Wojcik
- Haemostasis and Thrombosis Research Centre, University Hospital Leiden, The Netherlands.
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