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Han Y, Duan J, Chen M, Huang S, Zhang B, Wang Y, Liu J, Li X, Yu W. Relationship between serum sodium level and sepsis-induced coagulopathy. Front Med (Lausanne) 2024; 10:1324369. [PMID: 38298508 PMCID: PMC10828971 DOI: 10.3389/fmed.2023.1324369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 12/21/2023] [Indexed: 02/02/2024] Open
Abstract
Purpose A discussion about the correlation between the level of serum sodium and sepsis-induced coagulopathy (SIC). Materials and methods A retrospective analysis was conducted on sepsis patients who were admitted to the Intensive Care Unit (ICU) of Nanjing Drum Tower Hospital from January 2021 to December 2022. Based on the presence of coagulation disorders, the patients were divided into two groups: sepsis-induced coagulopathy (SIC) and non-sepsis-induced coagulopathy (non-SIC) groups. We recorded demographic characteristics and laboratory indicators at the time of ICU admission, and analyzed relationship between serum sodium level and SIC. Results One hundred and twenty-five patients with sepsis were enrolled, among which, the SIC and the non-SIC groups included 62 and 63 patients, respectively. Compared to patients in the non-SIC group, the level of serum sodium of those in the SIC was significantly higher (p < 0.001). Multi-factor logistic regression showed serum sodium level was independently associated with SIC (or = 1.127, p = 0.001). Pearson's correlation analysis indicated that the higher the serum sodium level, the significantly higher the SIC score was (r = 0.373, p < 0.001). Additionally, the mortality rate of patients with sepsis in the ICU were significantly correlated with increased serum sodium levels (p = 0.014). Conclusion An increase in serum sodium level was independently associated with an increased occurrence of SIC and also associated with the poor prognosis for patients with sepsis.
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Affiliation(s)
- Yanyu Han
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Drum Tower Clinical College, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jianfeng Duan
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Ming Chen
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Shijie Huang
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Drum Tower Clinical College, Nanjing University of Chinese Medicine, Nanjing, China
| | - Beiyuan Zhang
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Yan Wang
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Jiali Liu
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Xiaoyao Li
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Wenkui Yu
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Drum Tower Clinical College, Nanjing University of Chinese Medicine, Nanjing, China
- Department of Critical Care Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
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Stojanovski BM, Di Cera E. Comparative sequence analysis of vitamin K-dependent coagulation factors. J Thromb Haemost 2022; 20:2837-2849. [PMID: 36156849 PMCID: PMC9669250 DOI: 10.1111/jth.15897] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/22/2022] [Accepted: 09/22/2022] [Indexed: 01/13/2023]
Abstract
BACKGROUND Prothrombin, protein C, and factors VII, IX, and X are vitamin K (VK)-dependent coagulation proteins that play an important role in the initiation, amplification, and subsequent attenuation of the coagulation response. Blood coagulation evolved in the common vertebrate ancestor as a specialization of the complement system and immune response, which in turn bear close evolutionary ties with developmental enzyme cascades. There is currently no comprehensive analysis of the evolutionary changes experienced by these coagulation proteins during the radiation of vertebrates and little is known about conservation of residues that are important for zymogen activation and catalysis. OBJECTIVES To characterize the conservation level of functionally important residues among VK-dependent coagulation proteins from different vertebrate lineages. METHODS The conservation level of residues important for zymogen activation and catalysis was analyzed in >1600 primary sequences of VK-dependent proteins. RESULTS Functionally important residues are most conserved in prothrombin and least conserved in protein C. Some of the most profound functional modifications in protein C occurred in the ancestor of bony fish when the basic residue in the activation site was replaced by an aromatic residue. Furthermore, during the radiation of placental mammals from marsupials, protein C acquired a cysteine-rich insert that introduced an additional disulfide in the EGF1 domain and evolved a proprotein convertase cleavage site in the activation peptide linker that also became significantly elongated. CONCLUSIONS Sequence variabilities at functionally important residues may lead to interspecies differences in the zymogen activation and catalytic properties of orthologous VK-dependent proteins.
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Affiliation(s)
- Bosko M. Stojanovski
- Edward A. Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMissouriUSA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSt. LouisMissouriUSA
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3
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Vadivel K, Schmidt AE, Cascio D, Padmanabhan K, Krishnaswamy S, Brandstetter H, Bajaj SP. Structure of human factor VIIa-soluble tissue factor with calcium, magnesium and rubidium. Acta Crystallogr D Struct Biol 2021; 77:809-819. [PMID: 34076594 PMCID: PMC8171065 DOI: 10.1107/s2059798321003922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 04/12/2021] [Indexed: 11/10/2022] Open
Abstract
Coagulation factor VIIa (FVIIa) consists of a γ-carboxyglutamic acid (GLA) domain, two epidermal growth factor-like (EGF) domains and a protease domain. FVIIa binds three Mg2+ ions and four Ca2+ ions in the GLA domain, one Ca2+ ion in the EGF1 domain and one Ca2+ ion in the protease domain. Further, FVIIa contains an Na+ site in the protease domain. Since Na+ and water share the same number of electrons, Na+ sites in proteins are difficult to distinguish from waters in X-ray structures. Here, to verify the Na+ site in FVIIa, the structure of the FVIIa-soluble tissue factor (TF) complex was solved at 1.8 Å resolution containing Mg2+, Ca2+ and Rb+ ions. In this structure, Rb+ replaced two Ca2+ sites in the GLA domain and occupied three non-metal sites in the protease domain. However, Rb+ was not detected at the expected Na+ site. In kinetic experiments, Na+ increased the amidolytic activity of FVIIa towards the synthetic substrate S-2288 (H-D-Ile-Pro-Arg-p-nitroanilide) by ∼20-fold; however, in the presence of Ca2+, Na+ had a negligible effect. Ca2+ increased the hydrolytic activity of FVIIa towards S-2288 by ∼60-fold in the absence of Na+ and by ∼82-fold in the presence of Na+. In molecular-dynamics simulations, Na+ stabilized the two Na+-binding loops (the 184-loop and 220-loop) and the TF-binding region spanning residues 163-180. Ca2+ stabilized the Ca2+-binding loop (the 70-loop) and Na+-binding loops but not the TF-binding region. Na+ and Ca2+ together stabilized both the Na+-binding and Ca2+-binding loops and the TF-binding region. Previously, Rb+ has been used to define the Na+ site in thrombin; however, it was unsuccessful in detecting the Na+ site in FVIIa. A conceivable explanation for this observation is provided.
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Affiliation(s)
- Kanagasabai Vadivel
- Department of Orthopaedic Surgery, University of California, Los Angeles, CA 90095, USA
| | - Amy E. Schmidt
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Duilio Cascio
- DOE Institute for Genomics and Proteomics, University of California, Los Angeles, CA 90095, USA
| | | | - Sriram Krishnaswamy
- Division of Hematology, The Children’s Hospital of Philadelphia University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Hans Brandstetter
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria
| | - S. Paul Bajaj
- 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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4
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Mapping specificity, cleavage entropy, allosteric changes and substrates of blood proteases in a high-throughput screen. Nat Commun 2021; 12:1693. [PMID: 33727531 PMCID: PMC7966775 DOI: 10.1038/s41467-021-21754-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 02/10/2021] [Indexed: 02/06/2023] Open
Abstract
Proteases are among the largest protein families and critical regulators of biochemical processes like apoptosis and blood coagulation. Knowledge of proteases has been expanded by the development of proteomic approaches, however, technology for multiplexed screening of proteases within native environments is currently lacking behind. Here we introduce a simple method to profile protease activity based on isolation of protease products from native lysates using a 96FASP filter, their analysis in a mass spectrometer and a custom data analysis pipeline. The method is significantly faster, cheaper, technically less demanding, easy to multiplex and produces accurate protease fingerprints. Using the blood cascade proteases as a case study, we obtain protease substrate profiles that can be used to map specificity, cleavage entropy and allosteric effects and to design protease probes. The data further show that protease substrate predictions enable the selection of potential physiological substrates for targeted validation in biochemical assays. Characterizing proteases in their native environment is still challenging. Here, the authors develop a proteomics workflow for analyzing protease-specific peptides from cell lysates in 96-well format, providing mechanistic insights into blood proteases and enabling the prediction of protease substrates.
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5
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Ahnström J, Gierula M, Temenu J, Laffan MA, Lane DA. Partial rescue of naturally occurring active site factor X variants through decreased inhibition by tissue factor pathway inhibitor and antithrombin. J Thromb Haemost 2020; 18:136-150. [PMID: 31466141 DOI: 10.1111/jth.14627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 08/22/2019] [Accepted: 08/26/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Activated coagulation factor X (FXa) is the serine protease component of prothrombinase, the physiological activator of prothrombin. Factor X Nottingham (A404T) and Taunton (R405G) are two naturally occurring mutations, identified in families with a bleeding phenotype. OBJECTIVE To characterize these FX variants functionally. METHODS The activity and inhibition of recombinant FX variants were quantified in plasma-based and pure component assays. RESULTS The prothrombin times in FX-depleted plasma supplemented with FX Nottingham and Taunton were greatly increased compared to that of wild-type (WT) FX. Kinetic investigations of activated variants in the prothrombinase complex showed kcat /Km reduced ~50-fold and ~5-fold, respectively, explaining the prolonged prothrombin time (PT). The substituted residues are located in the protease domain Na+ -binding loop, important for the activity of FXa, as well as its inhibition. Both FXa Nottingham and Taunton showed reduced affinity for Na+ . Plasma-based thrombin generation assays triggered with 1 pmol/L tissue factor (TF) demonstrated only small differences in activities compared to WT FX, but large reductions at 10 pmol/L TF. Severely reduced inhibition of both FXa Nottingham and Taunton by tissue factor pathway inhibitor (TFPI) and antithrombin (AT), was shown in pure-component FXa inhibition assays. Factor Xa Nottingham and Taunton produced higher amounts of thrombin than WT FXa in pure-component prothrombinase assays in the presence of TFPI and AT, explaining the results from the plasma-based assay. CONCLUSIONS Factor X Nottingham and Taunton both display decreased proteolytic activity. However, their reduced activity in plasma triggered by low TF can be rescued by decreased inhibition by the natural FXa inhibitors, TFPI and AT.
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Affiliation(s)
- Josefin Ahnström
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, UK
| | - Magdalena Gierula
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, UK
| | - Joseph Temenu
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, UK
| | - Michael A Laffan
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, UK
| | - David A Lane
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, UK
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6
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Goettig P, Brandstetter H, Magdolen V. Surface loops of trypsin-like serine proteases as determinants of function. Biochimie 2019; 166:52-76. [PMID: 31505212 PMCID: PMC7615277 DOI: 10.1016/j.biochi.2019.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 09/06/2019] [Indexed: 02/07/2023]
Abstract
Trypsin and chymotrypsin-like serine proteases from family S1 (clan PA) constitute the largest protease group in humans and more generally in vertebrates. The prototypes chymotrypsin, trypsin and elastase represent simple digestive proteases in the gut, where they cleave nearly any protein. Multidomain trypsin-like proteases are key players in the tightly controlled blood coagulation and complement systems, as well as related proteases that are secreted from diverse immune cells. Some serine proteases are expressed in nearly all tissues and fluids of the human body, such as the human kallikreins and kallikrein-related peptidases with specialization for often unique substrates and accurate timing of activity. HtrA and membrane-anchored serine proteases fulfill important physiological tasks with emerging roles in cancer. The high diversity of all family members, which share the tandem β-barrel architecture of the chymotrypsin-fold in the catalytic domain, is conferred by the large differences of eight surface loops, surrounding the active site. The length of these loops alters with insertions and deletions, resulting in remarkably different three-dimensional arrangements. In addition, metal binding sites for Na+, Ca2+ and Zn2+ serve as regulatory elements, as do N-glycosylation sites. Depending on the individual tasks of the protease, the surface loops determine substrate specificity, control the turnover and allow regulation of activation, activity and degradation by other proteins, which are often serine proteases themselves. Most intriguingly, in some serine proteases, the surface loops interact as allosteric network, partially tuned by protein co-factors. Knowledge of these subtle and complicated molecular motions may allow nowadays for new and specific pharmaceutical or medical approaches.
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Affiliation(s)
- Peter Goettig
- Division of Structural Biology, Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria.
| | - Hans Brandstetter
- Division of Structural Biology, Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Viktor Magdolen
- Clinical Research Unit, Department of Obstetrics and Gynecology, School of Medicine, Technical University of Munich, Ismaninger Strasse 22, 81675, München, Germany
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7
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Structural determinants of specificity and regulation of activity in the allosteric loop network of human KLK8/neuropsin. Sci Rep 2018; 8:10705. [PMID: 30013126 PMCID: PMC6048020 DOI: 10.1038/s41598-018-29058-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/27/2018] [Indexed: 11/12/2022] Open
Abstract
Human KLK8/neuropsin, a kallikrein-related serine peptidase, is mostly expressed in skin and the hippocampus regions of the brain, where it regulates memory formation by synaptic remodeling. Substrate profiles of recombinant KLK8 were analyzed with positional scanning using fluorogenic tetrapeptides and the proteomic PICS approach, which revealed the prime side specificity. Enzyme kinetics with optimized substrates showed stimulation by Ca2+ and inhibition by Zn2+, which are physiological regulators. Crystal structures of KLK8 with a ligand-free active site and with the inhibitor leupeptin explain the subsite specificity and display Ca2+ bound to the 75-loop. The variants D70K and H99A confirmed the antagonistic role of the cation binding sites. Molecular docking and dynamics calculations provided insights in substrate binding and the dual regulation of activity by Ca2+ and Zn2+, which are important in neuron and skin physiology. Both cations participate in the allosteric surface loop network present in related serine proteases. A comparison of the positional scanning data with substrates from brain suggests an adaptive recognition by KLK8, based on the tertiary structures of its targets. These combined findings provide a comprehensive picture of the molecular mechanisms underlying the enzyme activity of KLK8.
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8
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Pijning AE, Chiu J, Yeo RX, Wong JWH, Hogg PJ. Identification of allosteric disulfides from labile bonds in X-ray structures. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171058. [PMID: 29515832 PMCID: PMC5830721 DOI: 10.1098/rsos.171058] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/03/2018] [Indexed: 05/08/2023]
Abstract
Protein disulfide bonds link pairs of cysteine sulfur atoms and are either structural or functional motifs. The allosteric disulfides control the function of the protein in which they reside when cleaved or formed. Here, we identify potential allosteric disulfides in all Protein Data Bank X-ray structures from bonds that are present in some molecules of a protein crystal but absent in others, or present in some structures of a protein but absent in others. We reasoned that the labile nature of these disulfides signifies a propensity for cleavage and so possible allosteric regulation of the protein in which the bond resides. A total of 511 labile disulfide bonds were identified. The labile disulfides are more stressed than the average bond, being characterized by high average torsional strain and stretching of the sulfur-sulfur bond and neighbouring bond angles. This pre-stress likely underpins their susceptibility to cleavage. The coagulation, complement and oxygen-sensing hypoxia inducible factor-1 pathways, which are known or have been suggested to be regulated by allosteric disulfides, are enriched in proteins containing labile disulfides. The identification of labile disulfide bonds will facilitate the study of this post-translational modification.
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Affiliation(s)
- Aster E. Pijning
- The Centenary Institute, Camperdown, New South Wales 2050, Australia
| | - Joyce Chiu
- The Centenary Institute, Camperdown, New South Wales 2050, Australia
- National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Reichelle X. Yeo
- The Centenary Institute, Camperdown, New South Wales 2050, Australia
| | - Jason W. H. Wong
- Prince of Wales Clinical School and Lowy Cancer Research Centre, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Philip J. Hogg
- The Centenary Institute, Camperdown, New South Wales 2050, Australia
- National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney, New South Wales 2006, Australia
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9
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Basagaoglu Demirekin Z, Aydemir Sezer U, Ulusoy Karatopuk D, Sezer S. Development of Metal Ion Binded Oxidized Regenerated Cellulose Powder as Hemostatic Agent: A Comparative Study with in Vivo Performance. Ind Eng Chem Res 2015. [DOI: 10.1021/ie504985b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zeynep Basagaoglu Demirekin
- Faculty of Dentistry, Department of Prosthodontics and ‡Faculty of Medicine,
Department of
Histology and Embryology, Suleyman Demirel University, 32260 Isparta, Turkey
- Materials
Institute and ⊥Chemistry Institute, TUBITAK Marmara Research Center, 41470 Kocaeli, Turkey
| | - Umran Aydemir Sezer
- Faculty of Dentistry, Department of Prosthodontics and ‡Faculty of Medicine,
Department of
Histology and Embryology, Suleyman Demirel University, 32260 Isparta, Turkey
- Materials
Institute and ⊥Chemistry Institute, TUBITAK Marmara Research Center, 41470 Kocaeli, Turkey
| | - Dilek Ulusoy Karatopuk
- Faculty of Dentistry, Department of Prosthodontics and ‡Faculty of Medicine,
Department of
Histology and Embryology, Suleyman Demirel University, 32260 Isparta, Turkey
- Materials
Institute and ⊥Chemistry Institute, TUBITAK Marmara Research Center, 41470 Kocaeli, Turkey
| | - Serdar Sezer
- Faculty of Dentistry, Department of Prosthodontics and ‡Faculty of Medicine,
Department of
Histology and Embryology, Suleyman Demirel University, 32260 Isparta, Turkey
- Materials
Institute and ⊥Chemistry Institute, TUBITAK Marmara Research Center, 41470 Kocaeli, Turkey
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10
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Xu N, Cioffi DL, Alexeyev M, Rich TC, Stevens T. Sodium entry through endothelial store-operated calcium entry channels: regulation by Orai1. Am J Physiol Cell Physiol 2014; 308:C277-88. [PMID: 25428882 DOI: 10.1152/ajpcell.00063.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Orai1 interacts with transient receptor potential protein of the canonical subfamily (TRPC4) and contributes to calcium selectivity of the endothelial cell store-operated calcium entry current (ISOC). Orai1 silencing increases sodium permeability and decreases membrane-associated calcium, although it is not known whether Orai1 is an important determinant of cytosolic sodium transitions. We test the hypothesis that, upon activation of store-operated calcium entry channels, Orai1 is a critical determinant of cytosolic sodium transitions. Activation of store-operated calcium entry channels transiently increased cytosolic calcium and sodium, characteristic of release from an intracellular store. The sodium response occurred more abruptly and returned to baseline more rapidly than did the transient calcium rise. Extracellular choline substitution for sodium did not inhibit the response, although 2-aminoethoxydiphenyl borate and YM-58483 reduced it by ∼50%. After this transient response, cytosolic sodium continued to increase due to influx through activated store-operated calcium entry channels. The magnitude of this sustained increase in cytosolic sodium was greater when experiments were conducted in low extracellular calcium and when Orai1 expression was silenced; these two interventions were not additive, suggesting a common mechanism. 2-Aminoethoxydiphenyl borate and YM-58483 inhibited the sustained increase in cytosolic sodium, only in the presence of Orai1. These studies demonstrate that sodium permeates activated store-operated calcium entry channels, resulting in an increase in cytosolic sodium; the magnitude of this response is determined by Orai1.
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Affiliation(s)
- Ningyong Xu
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Donna L Cioffi
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Mikhail Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Thomas C Rich
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Troy Stevens
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Department of Medicine, University of South Alabama, Mobile, Alabama; and Center for Lung Biology, University of South Alabama, Mobile, Alabama
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11
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Lu Q, Yang L, Manithody C, Wang X, Rezaie AR. Molecular basis of the clotting defect in a bleeding patient missing the Asp-185 codon in the factor X gene. Thromb Res 2014; 134:1103-9. [PMID: 25179519 DOI: 10.1016/j.thromres.2014.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/08/2014] [Accepted: 08/12/2014] [Indexed: 11/28/2022]
Abstract
Factor X (FX) is a vitamin K-dependent plasma zymogen, which following activation to factor Xa (FXa), converts prothrombin to thrombin in the blood clotting cascade. It was recently demonstrated that a natural variant of FX carrying the Asp-185 deletion (FX-D185del, chymotrypsinogen numbering) was associated with mild bleeding in a patient with severe FX deficiency. In this study, we expressed FX-D185del in mammalian cells and characterized its properties in appropriate kinetic assays in purified systems. We discovered that while the FX variant can be normally activated by physiological activators; both amidolytic and proteolytic activities of the mutant are dramatically impaired. Interestingly, factor Va (FVa) significantly improved the proteolytic defect when the mutant protease was assembled into the prothrombinase complex. Thus, in contrast to >50-fold catalytic defect in the absence of FVa, the variant activated prothrombin with only ~2.5-fold decreased catalytic efficiency in the presence of the cofactor. The FXa variant dramatically lost its susceptibility to inhibition by antithrombin and tissue factor pathway inhibitor, thus exhibiting ~2-3 orders of magnitude lower reactivity with the plasma inhibitors. Further studies revealed that Na(+) no longer activates the variant protease, suggesting that the functionally important allosteric linkage between the Na(+)-binding and the P1-binding sites of the protease has been eliminated. These results suggest that the lower catalytic efficiency of FXa-D185del in the bleeding patient may be partially compensated by the loss of its reactivity with plasma inhibitors, possibly explaining the basis for the paradoxical severe FX deficiency with only mild bleeding tendency for this mutation.
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Affiliation(s)
- Qiuya Lu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Likui Yang
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO, USA
| | - Chandrashekhara Manithody
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO, USA
| | - Xuefeng Wang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
| | - Alireza R Rezaie
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO, USA.
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12
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Majumder R, Koklic T, Rezaie AR, Lentz BR. Phosphatidylserine-induced factor Xa dimerization and binding to factor Va are competing processes in solution. Biochemistry 2013; 52:143-51. [PMID: 23214401 PMCID: PMC3544317 DOI: 10.1021/bi301239z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A soluble, short chain phosphatidylserine, 1,2-dicaproyl-sn-glycero-3-phospho-l-serine (C6PS), binds to discrete sites on FXa, FVa, and prothrombin to alter their conformations, to promote FXa dimerization (K(d) ~ 14 nM), and to enhance both the catalytic activity of FXa and the cofactor activity of FVa. In the presence of calcium, C6PS binds to two sites on FXa, one in the epidermal growth factor-like (EGF) domain and one in the catalytic domain; the latter interaction is sensitive to Na(+) binding and probably represents a protein recognition site. Here we ask whether dimerization of FXa and its binding to FVa in the presence of C6PS are competitive processes. We monitored FXa activity at 5, 20, and 50 nM FXa while titrating with FVa in the presence of 400 μM C6PS and 3 or 5 mM Ca(2+) to show that the apparent K(d) of FVa-FXa interaction increased with an increase in FXa concentration at 5 mM Ca(2+), but the K(d) was only slightly affected at 3 mM Ca(2+). A mixture of 50 nM FXa and 50 nM FVa in the presence of 400 μM C6PS yielded both Xa homodimers and Xa·Va heterodimers, but no FXa dimers bound to FVa. A mutant FXa (R165A) that has reduced prothrombinase activity showed both weakened dimerization (K(d) ~ 147 nM) and weakened FVa binding (apparent K(d) values of 58, 92, and 128 nM for 5, 20, and 50 nM R165A FXa, respectively). Native gel electrophoresis showed that the GLA-EGF(NC) fragment of FXa (lacking the catalytic domain) neither dimerized nor formed a complex with FVa in the presence of 400 μM C6PS and 5 mM Ca(2+). Our results demonstrate that the dimerization site and FVa-binding site are both located in the catalytic domain of FXa and that these sites are linked thermodynamically.
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Affiliation(s)
- Rinku Majumder
- Department of Biochemistry and Biophysics and Program in Molecular & Cellular Biophysics, CB # 7260, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7260
| | - Tilen Koklic
- Laboratory of Biophysics (EPR center), Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Alireza R. Rezaie
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO-63104
| | - Barry R. Lentz
- Department of Biochemistry and Biophysics and Program in Molecular & Cellular Biophysics, CB # 7260, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7260
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13
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Manithody C, Yang L, Rezaie AR. Identification of exosite residues of factor Xa involved in recognition of PAR-2 on endothelial cells. Biochemistry 2012; 51:2551-7. [PMID: 22409427 DOI: 10.1021/bi300200p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent results have indicated that factor Xa (FXa) cleaves protease-activated receptor 2 (PAR-2) to elicit protective intracellular signaling responses in endothelial cells. In this study, we investigated the molecular determinants of the specificity of FXa interaction with PAR-2 by monitoring the cleavage of PAR-2 by FXa in endothelial cells transiently transfected with a PAR-2 cleavage reporter construct in which the extracellular domain of the receptor was fused to cDNA encoding for alkaline phosphatase. Comparison of the cleavage efficiency of PAR-2 by a series of FXa mutants containing mutations in different surface loops indicated that the acidic residues of 39-loop (Glu-36, Glu-37, and Glu-39) and the basic residues of 60-loop (Lys-62 and Arg-63), 148-loop (Arg-143, Arg-150, and Arg-154), and 162-helix (Arg-165 and Lys-169) contribute to the specificity of receptor recognition by FXa on endothelial cells. This was evidenced by significantly reduced activity of mutants toward PAR-2 expressed on transfected cells. The extent of loss in the PAR-2 cleavage activity of FXa mutants correlated with the extent of loss in their PAR-2-dependent intracellular signaling activity. Further characterization of FXa mutants indicated that, with the exception of basic residues of 162-helix, which play a role in the recognition specificity of the prothrombinase complex, none of the surface loop residues under study makes a significant contribution to the activity of FXa in the prothrombinase complex. These results provide new insight into mechanisms through which FXa specifically interacts with its macromolecular substrates in the clotting and signaling pathways.
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Affiliation(s)
- Chandrashekhara Manithody
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States
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14
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Pozzi N, Chen R, Chen Z, Bah A, Di Cera E. Rigidification of the autolysis loop enhances Na(+) binding to thrombin. Biophys Chem 2011; 159:6-13. [PMID: 21536369 DOI: 10.1016/j.bpc.2011.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/04/2011] [Accepted: 04/04/2011] [Indexed: 01/09/2023]
Abstract
Binding of Na(+) to thrombin ensures high activity toward physiological substrates and optimizes the procoagulant and prothrombotic roles of the enzyme in vivo. Under physiological conditions of pH and temperature, the binding affinity of Na(+) is weak due to large heat capacity and enthalpy changes associated with binding, and the K(d)=80 mM ensures only 64% saturation of the site at the concentration of Na(+) in the blood (140 mM). Residues controlling Na(+) binding and activation have been identified. Yet, attempts to improve the interaction of Na(+) with thrombin and possibly increase catalytic activity under physiological conditions have so far been unsuccessful. Here we report how replacement of the flexible autolysis loop of human thrombin with the homologous rigid domain of the murine enzyme results in a drastic (up to 10-fold) increase in Na(+) affinity and a significant improvement in the catalytic activity of the enzyme. Rigidification of the autolysis loop abolishes the heat capacity change associated with Na(+) binding observed in the wild-type and also increases the stability of thrombin. These findings have general relevance to protein engineering studies of clotting proteases and trypsin-like enzymes.
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Affiliation(s)
- Nicola Pozzi
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
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15
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Abstract
Enzyme activation by monovalent cations is widely documented in plants and the animal world. In type II enzymes, activation entails two steps: binding of the monovalent cation to its allosteric site and transduction of this event into enhanced catalytic activity. The effect has exquisite specificity for either Na(+) or K(+), the most abundant cations present in physiological environments. Enzymes requiring K(+) such as kinases and molecular chaperones are not activated as well or at all by the larger cation Cs(+) or the smaller cations Na(+) and Li(+). Enzymes requiring Na(+) such as β-galactosidase and clotting proteases are not activated as well by Li(+), or the larger cations K(+), Rb(+), and Cs(+). Efforts to switch specificity between Na(+) and K(+) in this large class of enzymes and completely redesign the mechanism of allosteric transduction leading to enhanced catalytic activity have so far been unsuccessful. Here we show how mutagenesis of two loops defining the Na(+) binding site of thrombin, a Na(+)-activated clotting protease, generates a construct that is most active in the presence of K(+) toward synthetic and physiological substrates. The effect is the result of a higher binding affinity and more efficient allosteric transduction of binding into enhanced catalytic activity for K(+) compared to Na(+), which represents a complete reversal of the properties of wild type. In addition, the construct features altered specificity toward physiological substrates resulting in a significant anticoagulant profile. The findings are relevant to all Na(+)-activated proteases involved in blood coagulation and the complement system.
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Affiliation(s)
- Sadhna Rana
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
| | - Nicola Pozzi
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
| | - Leslie A. Pelc
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
| | - Enrico Di Cera
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104
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16
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Di Cera E. Thrombin as an Anticoagulant. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 99:145-84. [DOI: 10.1016/b978-0-12-385504-6.00004-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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17
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Vogt AD, Bah A, Di Cera E. Evidence of the E*-E equilibrium from rapid kinetics of Na+ binding to activated protein C and factor Xa. J Phys Chem B 2010; 114:16125-30. [PMID: 20809655 DOI: 10.1021/jp105502c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Na(+) binding to thrombin enhances the procoagulant and prothrombotic functions of the enzyme and obeys a mechanism that produces two kinetic phases: one fast (in the microsecond time scale) due to Na(+) binding to the low activity form E to produce the high activity form E:Na(+) and another considerably slower (in the millisecond time scale) that reflects a pre-equilibrium between E and the inactive form E*. In this study, we demonstrate that this mechanism also exists in other Na(+)-activated clotting proteases like factor Xa and activated protein C. These findings, along with recent structural data, suggest that the E*-E equilibrium is a general feature of the trypsin fold.
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Affiliation(s)
- Austin D Vogt
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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18
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Ono Y, Ojima K, Torii F, Takaya E, Doi N, Nakagawa K, Hata S, Abe K, Sorimachi H. Skeletal muscle-specific calpain is an intracellular Na+-dependent protease. J Biol Chem 2010; 285:22986-98. [PMID: 20460380 PMCID: PMC2906292 DOI: 10.1074/jbc.m110.126946] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Because intracellular [Na+] is kept low by Na+/K+-ATPase, Na+ dependence is generally considered a property of extracellular enzymes. However, we found that p94/calpain 3, a skeletal-muscle-specific member of the Ca2+-activated intracellular “modulator proteases” that is responsible for a limb-girdle muscular dystrophy (“calpainopathy”), underwent Na+-dependent, but not Cs+-dependent, autolysis in the absence of Ca2+. Furthermore, Na+ and Ca2+ complementarily activated autolysis of p94 at physiological concentrations. By blocking Na+/K+-ATPase, we confirmed intracellular autolysis of p94 in cultured cells. This was further confirmed using inactive p94:C129S knock-in (p94CS-KI) mice as negative controls. Mutagenesis studies showed that much of the p94 molecule contributed to its Na+/Ca2+-dependent autolysis, which is consistent with the scattered location of calpainopathy-associated mutations, and that a conserved Ca2+-binding sequence in the protease acted as a Na+ sensor. Proteomic analyses using Cs+/Mg2+ and p94CS-KI mice as negative controls revealed that Na+ and Ca2+ direct p94 to proteolyze different substrates. We propose three roles for Na+ dependence of p94; 1) to increase sensitivity of p94 to changes in physiological [Ca2+], 2) to regulate substrate specificity of p94, and 3) to regulate contribution of p94 as a structural component in muscle cells. Finally, this is the first example of an intracellular Na+-dependent enzyme.
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Affiliation(s)
- Yasuko Ono
- Calpain Project, The Tokyo Metropolitan Institute of Medical Science (Rinshoken), Tokyo 156-8506, Japan
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19
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Page MJ, Di Cera E. Combinatorial enzyme design probes allostery and cooperativity in the trypsin fold. J Mol Biol 2010; 399:306-19. [PMID: 20399789 DOI: 10.1016/j.jmb.2010.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 04/12/2010] [Accepted: 04/13/2010] [Indexed: 01/05/2023]
Abstract
Converting one enzyme into another is challenging due to the uneven distribution of important amino acids for function in both protein sequence and structure. We report a strategy for protein engineering allowing an organized mixing and matching of genetic material that leverages lower throughput with increased quality of screens. Our approach successfully tested the contribution of each surface-exposed loop in the trypsin fold alone and the cooperativity of their combinations towards building the substrate selectivity and Na(+)-dependent allosteric activation of the protease domain of human coagulation factor Xa into a bacterial trypsin. As the created proteases lack additional protein domains and protein co-factor activation mechanism requisite for the complexity of blood coagulation, they are stepping-stones towards further understanding and engineering of artificial clotting factors.
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Affiliation(s)
- Michael J Page
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
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20
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Niu W, Chen Z, Bush-Pelc LA, Bah A, Gandhi PS, Di Cera E. Mutant N143P reveals how Na+ activates thrombin. J Biol Chem 2009; 284:36175-36185. [PMID: 19846563 PMCID: PMC2794733 DOI: 10.1074/jbc.m109.069500] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/12/2009] [Indexed: 01/09/2023] Open
Abstract
The molecular mechanism of thrombin activation by Na(+) remains elusive. Its kinetic formulation requires extension of the classical Botts-Morales theory for the action of a modifier on an enzyme to correctly account for the contribution of the E*, E, and E:Na(+) forms. The extended scheme establishes that analysis of k(cat) unequivocally identifies allosteric transduction of Na(+) binding into enhanced catalytic activity. The thrombin mutant N143P features no Na(+)-dependent enhancement of k(cat) yet binds Na(+) with an affinity comparable to that of wild type. Crystal structures of the mutant in the presence and absence of Na(+) confirm that Pro(143) abrogates the important H-bond between the backbone N atom of residue 143 and the carbonyl O atom of Glu(192), which in turn controls the orientation of the Glu(192)-Gly(193) peptide bond and the correct architecture of the oxyanion hole. We conclude that Na(+) activates thrombin by securing the correct orientation of the Glu(192)-Gly(193) peptide bond, which is likely flipped in the absence of cation. Absolute conservation of the 143-192 H-bond in trypsin-like proteases and the importance of the oxyanion hole in protease function suggest that this mechanism of Na(+) activation is present in all Na(+)-activated trypsin-like proteases.
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Affiliation(s)
- Weiling Niu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Zhiwei Chen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Leslie A Bush-Pelc
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Alaji Bah
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Prafull S Gandhi
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
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21
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Qureshi SH, Yang L, Manithody C, Iakhiaev AV, Rezaie AR. Mutagenesis studies toward understanding allostery in thrombin. Biochemistry 2009; 48:8261-70. [PMID: 19640005 DOI: 10.1021/bi900921t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The binding of thrombomodulin (TM) to exosite-1 and the binding of Na(+) to 225-loop allosterically modulate the catalytic activity and substrate specificity of thrombin. To determine whether the conformation of these two cofactor-binding loops are energetically linked to each other and to the active site, we rationally designed two thrombin mutants in which either the 70-80 loop of exosite-1 or the 225-loop of the Na(+)-binding site was stabilized by an engineered disulfide bond. This was possible by replacing two residues, Arg-67 and Ile-82, in the first mutant and two residues, Glu-217 and Lys-224, in the second mutant with Cys residues. These mutants were expressed in mammalian cells as monomeric molecules, purified to homogeneity and characterized with respect to their ability to bind TM and Na(+) by kinetic and direct binding approaches. The Cys-67/Cys-82 mutant did not bind TM and exhibited a normal amidolytic activity, however, the activity of Cys-217/Cys-224 was dramatically impaired, though TM interacted with this mutant with >20-fold elevated K(D) to partially restore its activity. Both mutants exhibited approximately 2-3-fold higher K(D) for interaction with Na(+), and neither mutant clotted fibrinogen or activated protein C in the presence of TM. Both mutants interacted with heparin with a normal affinity. These results suggest that, while exosite-2 of thrombin is an independent cofactor binding-site, both Na(+)-binding and exosite-1 are energetically linked. Further studies with the fluorescein labeled Cys-195 mutant of thrombin revealed that the catalytic residue of thrombin is modulated by Na(+), but TM has no effect on the conformation of this residue.
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Affiliation(s)
- Shabir H Qureshi
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, USA
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22
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Chattopadhyay R, Iacob R, Sen S, Majumder R, Tomer KB, Lentz BR. Functional and structural characterization of factor Xa dimer in solution. Biophys J 2009; 96:974-86. [PMID: 19186135 DOI: 10.1016/j.bpj.2008.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 10/14/2008] [Indexed: 10/21/2022] Open
Abstract
Previous studies showed that binding of water-soluble phosphatidylserine (C6PS) to bovine factor Xa (FXa) leads to Ca2+-dependent dimerization in solution. We report the effects of Ca2+, C6PS, and dimerization on the activity and structure of human and bovine FXa. Both human and bovine dimers are 10(6)- to 10(7)-fold less active toward prothrombin than the monomer, with the decrease being attributed mainly to a substantial decrease in k(cat). Dimerization appears not to block the active site, since amidolytic activity toward a synthetic substrate is largely unaffected. Circular dichroism reveals a substantial change in tertiary or quaternary structure with a concomitant decrease in alpha-helix upon dimerization. Mass spectrometry identifies a lysine (K(270)) in the catalytic domain that appears to be buried at the dimer interface and is part of a synthetic peptide sequence reported to interfere with factor Va (FVa) binding. C6PS binding exposes K(351) (part of a reported FVa binding region), K(242) (adjacent to the catalytic triad), and K(420) (part of a substrate exosite). We interpret our results to mean that C6PS-induced dimerization produces substantial conformational changes or domain rearrangements such that structural data on PS-activated FXa is required to understand the structure of the FXa dimer or the FXa-FVa complex.
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Affiliation(s)
- Rima Chattopadhyay
- Department of Biochemistry and Biophysics and Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA
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23
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Abstract
Meizothrombin is the physiologically active intermediate generated by a single cleavage of prothrombin at R320 to separate the A and B chains. Recent evidence has suggested that meizothrombin, like thrombin, is a Na(+)-activated enzyme. In this study we present the first X-ray crystal structure of human meizothrombin desF1 solved in the presence of the active site inhibitor PPACK at 2.1 A resolution. The structure reveals a Na(+) binding site whose architecture is practically identical to that of human thrombin. Stopped-flow measurements of Na(+) binding to meizothrombin desF1 document a slow phase of fluorescence change with a k(obs) decreasing hyperbolically with increasing [Na(+)], consistent with the existence of three conformations in equilibrium, E*, E and E:Na(+), as for human thrombin. Evidence that meizothrombin exists in multiple conformations provides valuable new information for studies of the mechanism of prothrombin activation.
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Affiliation(s)
- M. E. Papaconstantinou
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110 USA
| | - P. S. Gandhi
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110 USA
| | - Z. Chen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110 USA
| | - A. Bah
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110 USA
| | - E. Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110 USA
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24
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Toso R, Zhu H, Camire RM. The conformational switch from the factor X zymogen to protease state mediates exosite expression and prothrombinase assembly. J Biol Chem 2008; 283:18627-35. [PMID: 18460471 DOI: 10.1074/jbc.m802205200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Zymogens of the chymotrypsin-like serine protease family are converted to the protease state following insertion of a newly formed, highly conserved N terminus. This transition is accompanied by active site formation and ordering of several surface loops in the catalytic domain. Here we show that disruption of this transition in factor X through mutagenesis (FXa(I16L) and FXa(V17A)) not only alters active site function, but also significantly impairs Na(+) and factor Va binding. Active site binding was improved in the presence of high NaCl or with saturating amounts of factor Va membranes, suggesting that allosteric linkage exists between these sites. In line with this, irreversible stabilization of FXa(I16L) with Glu-Gly-Arg-chloromethyl ketone fully rescued FVa binding. Furthermore, the K(m) for prothrombin conversion with the factor Xa variants assembled into prothrombinase was unaltered, whereas the k(cat) was modestly reduced (3- to 4-fold). These findings show that intramolecular activation of factor X following the zymogen to protease transition not only drives catalytic site activation but also contributes to the formation of the Na(+) and factor Va binding sites. This structural plasticity of the catalytic domain plays a key role in the regulation of exosite expression and prothrombinase assembly.
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Affiliation(s)
- Raffaella Toso
- Department of Pediatrics, Division of Hematology, The Children's Hospital of Philadelphia, Pennsylvania 19104, USA
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25
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Yang L, Manithody C, Qureshi SH, Rezaie AR. Factor Va alters the conformation of the Na+-binding loop of factor Xa in the prothrombinase complex. Biochemistry 2008; 47:5976-85. [PMID: 18457426 DOI: 10.1021/bi800319r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structural and mutagenesis data have indicated that the 220-loop of thrombin is stabilized by a salt-bridge between Glu-217 and Lys-224, thereby facilitating the octahedral coordination of Na (+) with contributions from two carbonyl O atoms of Arg-221a and Lys-224. All three residues are also conserved in fXa and the X-ray crystal structure of fXa indicates that both Glu-217 and Lys-224 are within hydrogen-bonding distance from one another. To investigate the role of these three residues in the catalytic function of fXa and their contribution to interaction with Na (+), we substituted them with Ala and characterized their properties in both amidolytic and proteolytic activity assays. The results indicate that the affinity of all three mutants for interaction with Na (+) has been impaired. The mutant with the greatest loss of affinity for Na (+) (E217A or E217Q) also exhibited a dramatic impairment ( approximately 3-4 orders of magnitude) in its activity toward both synthetic and natural substrates. Interestingly, factor Va (fVa) restored most of the catalytic defect with prothrombin, but not with the synthetic substrate. Both Glu-217 mutants exhibited a near normal affinity for fVa in the prothrombinase assay, but a markedly lower affinity for the cofactor in a direct-binding assay. These results suggest that, similar to thrombin, an ionic interaction between Glu-217 and Lys-224 stabilizes the 220-loop of fXa for binding Na (+). They further support the hypothesis that the Na (+) and fVa-binding sites of fXa are energetically linked and that a cofactor function for fVa in the prothrombinase complex involves inducing a conformational change in the 220-loop of fXa that appears to stabilize this loop in the Na (+)-bound active conformation.
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Affiliation(s)
- Likui Yang
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, USA
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26
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Page MJ, Carrell CJ, Di Cera E. Engineering protein allostery: 1.05 A resolution structure and enzymatic properties of a Na+-activated trypsin. J Mol Biol 2008; 378:666-72. [PMID: 18377928 DOI: 10.1016/j.jmb.2008.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 02/29/2008] [Accepted: 03/04/2008] [Indexed: 11/28/2022]
Abstract
Some trypsin-like proteases are endowed with Na(+)-dependent allosteric enhancement of catalytic activity, but this important mechanism has been difficult to engineer in other members of the family. Replacement of 19 amino acids in Streptomyces griseus trypsin targeting the active site and the Na(+)-binding site were found necessary to generate efficient Na(+) activation. Remarkably, this property was linked to the acquisition of a new substrate selectivity profile similar to that of factor Xa, a Na(+)-activated protease involved in blood coagulation. The X-ray crystal structure of the mutant trypsin solved to 1.05 A resolution defines the engineered Na(+) site and active site loops in unprecedented detail. The results demonstrate that trypsin can be engineered into an efficient allosteric protease, and that Na(+) activation is interwoven with substrate selectivity in the trypsin scaffold.
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Affiliation(s)
- Michael J Page
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Box 8231, St. Louis, MO 63110, USA
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27
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Abstract
Thrombin is a Na+-activated, allosteric serine protease that plays opposing functional roles in blood coagulation. Binding of Na+ is the major driving force behind the procoagulant, prothrombotic and signaling functions of the enzyme, but is dispensable for cleavage of the anticoagulant protein C. The anticoagulant function of thrombin is under the allosteric control of the cofactor thrombomodulin. Much has been learned on the mechanism of Na+ binding and recognition of natural substrates by thrombin. Recent structural advances have shed light on the remarkable molecular plasticity of this enzyme and the molecular underpinnings of thrombin allostery mediated by binding to exosite I and the Na+ site. This review summarizes our current understanding of the molecular basis of thrombin function and allosteric regulation. The basic information emerging from recent structural, mutagenesis and kinetic investigation of this important enzyme is that thrombin exists in three forms, E*, E and E:Na+, that interconvert under the influence of ligand binding to distinct domains. The transition between the Na+ -free slow from E and the Na+ -bound fast form E:Na+ involves the structure of the enzyme as a whole, and so does the interconversion between the two Na+ -free forms E* and E. E* is most likely an inactive form of thrombin, unable to interact with Na + and substrate. The complexity of thrombin function and regulation has gained this enzyme pre-eminence as the prototypic allosteric serine protease. Thrombin is now looked upon as a model system for the quantitative analysis of biologically important enzymes.
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Affiliation(s)
- Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University Medical School, St. Louis, MO 63110, United States.
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28
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Levigne S, Thiec F, Cherel G, Irving JA, Fribourg C, Christophe OD. Role of the alpha-helix 163-170 in factor Xa catalytic activity. J Biol Chem 2007; 282:31569-79. [PMID: 17726015 DOI: 10.1074/jbc.m704837200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Factor Xa (FXa) is a key protease of the coagulation pathway whose activity is known to be in part modulated by binding to factor Va (FVa) and sodium ions. Previous investigations have established that solvent-exposed, charged residues of the FXa alpha-helix 163-170 (h163-170), Arg(165) and Lys(169), participate in its binding to FVa. In the present study we aimed to investigate the role of the other residues of h163-170 in the catalytic functions of the enzyme. FX derivatives were constructed in which point mutations were made or parts of h163-170 were substituted with the corresponding region of either FVIIa or FIXa. Purified FXa derivatives were compared with wild-type FXa. Kinetic studies in the absence of FVa revealed that, compared with wild-type FXa, key functional parameters (catalytic activity toward prothrombin and tripeptidyl substrates and non-enzymatic interaction of a probe with the S1 site) were diminished by mutations in the NH(2)-terminal portion of h163-170. The defective amidolytic activity of these FXa derivatives appears to result from their impaired interaction with Na(+) because using a higher Na(+) concentration partially restored normal catalytic parameters. Furthermore, kinetic measurements with tripeptidyl substrates or prothrombin indicated that assembly of these FXa derivatives with an excess of FVa in the prothrombinase complex improves their low catalytic efficiency. These data indicate that residues in the NH(2)-terminal portion of the FVa-binding h163-170 are energetically linked to the S1 site and Na(+)-binding site of the protease and that residues Val(163) and Ser(167) play a key role in this interaction.
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Affiliation(s)
- Stéphanie Levigne
- INSERM U770 and Université Paris-Sud, F-94276, Le Kremlin-Bicêtre, France
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29
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Abstract
The specificity of blood coagulation proteinases for substrate, inhibitor, and effector recognition is mediated by exosites on the surfaces of the catalytic domains, physically separated from the catalytic site. Some thrombin ligands bind specifically to either exosite I or II, while others engage both exosites. The involvement of different, overlapping constellations of exosite residues enables binding of structurally diverse ligands. The flexibility of the thrombin structure is central to the mechanism of complex formation and the specificity of exosite interactions. Encounter complex formation is driven by electrostatic ligand-exosite interactions, followed by conformational rearrangement to a stable complex. Exosites on some zymogens are in low affinity proexosite states and are expressed concomitant with catalytic site activation. The requirement for exosite expression controls the specificity of assembly of catalytic complexes on the coagulation pathway, such as the membrane-bound factor Xa*factor Va (prothrombinase) complex, and prevents premature assembly. Substrate recognition by prothrombinase involves a two-step mechanism with initial docking of prothrombin to exosites, followed by a conformational change to engage the FXa catalytic site. Prothrombin and its activation intermediates bind prothrombinase in two alternative conformations determined by the zymogen to proteinase transition that are hypothesized to involve prothrombin (pro)exosite I interactions with FVa, which underpin the sequential activation pathway. The role of exosites as the major source of substrate specificity has stimulated development of exosite-targeted anticoagulants for treatment of thrombosis.
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Affiliation(s)
- P E Bock
- Department of Pathology, Vanderbilt University, Nashville, TN 37232-2561, USA.
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30
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Kroh HK, Tans G, Nicolaes GAF, Rosing J, Bock PE. Expression of allosteric linkage between the sodium ion binding site and exosite I of thrombin during prothrombin activation. J Biol Chem 2007; 282:16095-104. [PMID: 17430903 PMCID: PMC2292469 DOI: 10.1074/jbc.m610577200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The specificity of thrombin for procoagulant and anticoagulant substrates is regulated allosterically by Na+. Ordered cleavage of prothrombin (ProT) at Arg320 by the prothrombinase complex generates proteolytically active, meizothrombin (MzT), followed by cleavage at Arg271 to produce thrombin and fragment 1.2. The alternative pathway of initial cleavage at Arg271 produces the inactive zymogen form, the prethrombin 2 (Pre 2).fragment 1.2 complex, which is cleaved subsequently at Arg320. Cleavage at Arg320 of ProT or prethrombin 1 (Pre 1) activates the catalytic site and the precursor form of exosite I (proexosite I). To determine the pathway of expression of Na+-(pro)exosite I linkage during ProT activation, the effects of Na+ on the affinity of fluorescein-labeled hirudin-(54-65) ([5F]Hir-(54-65)(SO-3)) for the zymogens, ProT, Pre 1, and Pre 2, and for the proteinases, MzT and MzT-desfragment 1 (MzT(-F1)) were quantitated. The zymogens showed no significant linkage between proexosite I and Na+, whereas cleavage at Arg320 caused the affinities of MzT and MzT(-F1) for [5F]Hir-(54-65)(SO-3) to be enhanced by Na+ 8- to 10-fold and 5- to 6-fold, respectively. MzT and MzT(-F1) showed kinetically different mechanisms of Na+ enhancement of chromogenic substrate hydrolysis. The results demonstrate for the first time that MzT is regulated allosterically by Na+. The results suggest that the distinctive procoagulant substrate specificity of MzT, in activating factor V and factor VIII on membranes, and the anticoagulant, membrane-modulated activation of protein C by MzT bound to thrombomodulin are regulated by Na+-induced allosteric transition. Further, the Na+ enhancement in MzT activity and exosite I affinity may function in directing the sequential ProT activation pathway by accelerating thrombin formation from the MzT fast form.
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Affiliation(s)
- Heather K. Kroh
- Department of Pathology, Vanderbilt University, Nashville, Tennessee 37232
| | - Guido Tans
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, University Maastricht, Maastricht 6200MD, The Netherlands
| | - Gerry A. F. Nicolaes
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, University Maastricht, Maastricht 6200MD, The Netherlands
| | - Jan Rosing
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, University Maastricht, Maastricht 6200MD, The Netherlands
| | - Paul E. Bock
- Department of Pathology, Vanderbilt University, Nashville, Tennessee 37232
- To whom correspondence should be addressed: Dept. of Pathology, Vanderbilt University School of Medicine, C3321A Medical Center North, Nashville, TN 37232-2561. Tel.: 615-343-9863; Fax: 615-322-1855; E-mail:
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31
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Marino F, Chen ZW, Ergenekan CE, Bush-Pelc LA, Mathews FS, Di Cera E. Structural basis of Na+ activation mimicry in murine thrombin. J Biol Chem 2007; 282:16355-61. [PMID: 17428793 DOI: 10.1074/jbc.m701323200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Unlike human thrombin, murine thrombin lacks Na+ activation due to the charge reversal substitution D222K in the Na+ binding loop. However, the enzyme is functionally stabilized in a Na+-bound form and is highly active toward physiologic substrates. The structural basis of this peculiar property is unknown. Here, we present the 2.2 A resolution x-ray crystal structure of murine thrombin in the absence of inhibitors and salts. The enzyme assumes an active conformation, with Ser-195, Glu-192, and Asp-189 oriented as in the Na+-bound fast form of human thrombin. Lys-222 completely occludes the pore of entry to the Na+ binding site and positions its side chain inside the pore, with the Nzeta atom H-bonded to the backbone oxygen atoms of Lys-185, Asp-186b, and Lys-186d. The same architecture is observed in the 1.75 A resolution structure of a thrombin chimera in which the human enzyme carries all residues defining the Na+ pore in the murine enzyme. These findings demonstrate that Na+ activation in thrombin is linked to the architecture of the Na+ pore. The molecular strategy of Na+ activation mimicry unraveled for murine thrombin is relevant to serine proteases and enzymes activated by monovalent cations in general.
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Affiliation(s)
- Francesca Marino
- Department of Biochemistry and Molecular Biophysics, Washington University Medical School, St. Louis, Missouri 63110, USA
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32
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Abstract
Thrombin is a Na(+)-activated, allosteric serine protease that plays multiple functional roles in blood pathophysiology. Binding of Na(+) is the major driving force behind the procoagulant, prothrombotic and signaling functions of the enzyme. This review summarizes our current understanding of the molecular basis of thrombin allostery with special emphasis on the kinetic aspects of Na(+) activation. The molecular mechanism of thrombin allostery is a remarkable example of long-range communication that offers a paradigm for many other biological systems.
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Affiliation(s)
- Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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33
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Yang L, Gopalakrishna K, Manithody C, Rezaie AR. Expression, purification and characterization of factor IX derivatives using a novel vector system. Protein Expr Purif 2006; 50:196-202. [PMID: 16829135 DOI: 10.1016/j.pep.2006.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 05/23/2006] [Indexed: 11/23/2022]
Abstract
Recent studies have indicated that the loop harboring the S1 specificity site (residues 185-189 in chymotrypsin numbering) of coagulation proteases has several charged residues with important structural and functional roles for the catalytic activity of these proteases. This loop is allosterically linked to the Na(+)-binding site in both factor Xa and thrombin. There are three candidate residues (His-185, Glu-186, and Arg-188) on this loop of factor IXa (fIXa) whose side chains can influence the Na(+) binding and the catalytic function of the protease in the intrinsic Xase complex. In this study, we developed a novel expression/purification vector system, substituted all three residues of factor IX individually with Ala, and expressed the mutant zymogens in mammalian cells. Following activation, all three fIXa mutants exhibited normal activity towards a fIXa-specific chromogenic substrate in the presence of Ca(2+) with no obvious requirement for Na(+) in the reaction. Furthermore, all three mutants interacted with factor VIIIa with near normal affinity and catalyzed the activation of factor X in the intrinsic Xase complex with a normal catalytic efficiency. These results suggest that, unlike thrombin and factor Xa, the charged residues of this loop do not play a functional role in modulating the catalytic function of fIXa in the intrinsic Xase complex.
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Affiliation(s)
- Likui Yang
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
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34
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Abstract
Metal complexation is a key mediator or modifier of enzyme structure and function. In addition to divalent and polyvalent metals, group IA metals Na+and K+play important and specific roles that assist function of biological macromolecules. We examine the diversity of monovalent cation (M+)-activated enzymes by first comparing coordination in small molecules followed by a discussion of theoretical and practical aspects. Select examples of enzymes that utilize M+as a cofactor (type I) or allosteric effector (type II) illustrate the structural basis of activation by Na+and K+, along with unexpected connections with ion transporters. Kinetic expressions are derived for the analysis of type I and type II activation. In conclusion, we address evolutionary implications of Na+binding in the trypsin-like proteases of vertebrate blood coagulation. From this analysis, M+complexation has the potential to be an efficient regulator of enzyme catalysis and stability and offers novel strategies for protein engineering to improve enzyme function.
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Affiliation(s)
- Michael J Page
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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35
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Bush LA, Nelson RW, Di Cera E. Murine Thrombin Lacks Na+ Activation but Retains High Catalytic Activity. J Biol Chem 2006; 281:7183-8. [PMID: 16428384 DOI: 10.1074/jbc.m512082200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Human thrombin utilizes Na+ as a driving force for the cleavage of substrates mediating its procoagulant, prothrombotic, and signaling functions. Murine thrombin has Asp-222 in the Na+ binding site of the human enzyme replaced by Lys. The charge reversal substitution abrogates Na+ activation, which is partially restored with the K222D mutation, and ensures high activity even in the absence of Na+. This property makes the murine enzyme more resistant to the effect of mutations that destabilize Na+ binding and shift thrombin to its anticoagulant slow form. Compared with the human enzyme, murine thrombin cleaves fibrinogen and protein C with similar k(cat)/K(m) values but activates PAR1 and PAR4 with k(cat)/K(m) values 4- and 26-fold higher, respectively. The significantly higher specificity constant toward PAR4 accounts for the dominant role of this receptor in platelet activation in the mouse. Murine thrombin can also cleave substrates carrying Phe at P1, which potentially broadens the repertoire of molecular targets available to the enzyme in vivo.
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Affiliation(s)
- Leslie A Bush
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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36
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Abstract
Proteases play diverse roles in a variety of essential biological processes, both as non-specific catalysts of protein degradation and as highly specific agents that control physiologic events. Here, we review the mechanisms of substrate specificity employed by serine proteases and focus our discussion on coagulation proteases. We dissect the interplay between active site and exosite specificity and how substrate recognition is regulated allosterically by Na+ binding. We also draw attention to a functional polarity that exists in the serine protease fold, which sheds light on the structural linkages between the active site and exosites.
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Affiliation(s)
- M J Page
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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37
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Abstract
Enzymes activated by monovalent cations are abundantly represented in plants and in the animal world. The mechanism, of activation involves formation of a ternary intermediate with the enzyme-substrate complex, or binding of the cation to an allosteric site in the protein. Thrombin is a Na+-activated enzyme with procoagulant, anticoagulant and signaling roles. The binding of Na+ influences allosterically thrombin function and offers a paradigm for regulatory control of protease activity and specificity. Here we review the molecular basis of thrombin allostery as recently emerged from mutagenesis and structural studies. The role of Na+ in blood coagulation and the evolution of serine proteases are also discussed.
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Affiliation(s)
- Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA.
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38
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Mengwasser KE, Bush LA, Shih P, Cantwell AM, Di Cera E. Hirudin Binding Reveals Key Determinants of Thrombin Allostery. J Biol Chem 2005; 280:26997-7003. [PMID: 15923186 DOI: 10.1074/jbc.m502678200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thrombin exists in two allosteric forms, slow (S) and fast (F), that recognize natural substrates and inhibitors with significantly different affinities. Because under physiologic conditions the two forms are almost equally populated, investigation of thrombin function must address the contribution from the S and F forms and the molecular origin of their differential recognition of ligands. Using a panel of 79 Ala mutants, we have mapped for the first time the epitopes of thrombin recognizing a macromolecular ligand, hirudin, in the S and F forms. Hirudin binding is a relevant model for the interaction of thrombin with fibrinogen and PAR1 and is likewise influenced by the allosteric S-->F transition. The epitopes are nearly identical and encompass two hot spots, one in exosite I and the other in the Na+ site at the opposite end of the protein. The higher affinity of the F form is due to the preferential interaction of hirudin with Lys-36, Leu-65, Thr-74, and Arg-75 in exosite I; Gly-193 in the oxyanion hole; and Asp-221 and Asp-222 in the Na+ site. Remarkably, no correlation is found between the energetic and structural involvements of thrombin residues in hirudin recognition, which invites caution in the analysis of protein-protein interactions in general.
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Affiliation(s)
- Kristen E Mengwasser
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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39
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Chen L, Manithody C, Yang L, Rezaie AR. Zymogenic and enzymatic properties of the 70-80 loop mutants of factor X/Xa. Protein Sci 2004; 13:431-42. [PMID: 14739327 PMCID: PMC2286711 DOI: 10.1110/ps.03406904] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The Ca(2+) binding 70-80 loop of factor X (fX) contains one basic (Arg(71)) and three acidic (Glu(74), Glu(76), and Glu(77)) residues whose contributions to the zymogenic and enzymatic properties of the protein have not been evaluated. We prepared four Ala substitution mutants of fX (R71A, E74A, E76A, and E77A) and characterized their activation kinetics by the factor VIIa and factor IXa in both the absence and presence of cofactors. Factor VIIa exhibited normal activity toward E74A and E76A and less than a twofold impaired activity toward R71A and E77A in both the absence and presence of tissue factor. Similarly, factor IXa in the absence of factor VIIIa exhibited normal activity toward both E74A and E76A; however, its activity toward R71A and E77A was impaired approximately two- to threefold. In the presence of factor VIIIa, factor IX activated all mutants with approximately two- to fivefold impaired catalytic efficiency. In contrast to changes in their zymogenic properties, all mutant enzymes exhibited normal affinities for factor Va, and catalyzed the conversion of prothrombin to thrombin with normal catalytic efficiencies. However, further studies revealed that the affinity of mutant enzymes for interaction with metal ions Na(+) and Ca(2+) was impaired. These results suggest that although charged residues of the 70-80 loop play an insignificant role in fX recognition by the factor VIIa-tissue factor complex, they are critical for the substrate recognition by factor IXa in the intrinsic Xase complex. The results further suggest that mutant residues do not play a specific role in the catalytic function of fXa in the prothrombinase complex.
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Affiliation(s)
- Lin Chen
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1402 S. Grand Blvd., St. Louis, MO 63104, USA
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40
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Rezaie AR, Kittur FS. The critical role of the 185-189-loop in the factor Xa interaction with Na+ and factor Va in the prothrombinase complex. J Biol Chem 2004; 279:48262-9. [PMID: 15347660 DOI: 10.1074/jbc.m409964200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The S1 site (Asp(189)) of factor Xa (fXa) is located on a loop (residues 185-189) that contains three solvent-exposed charged residues (Asp(185), Lys(186), and Glu(188)) below the active-site pocket of the protease. To investigate the role of these residues in the catalytic function of fXa, we expressed three mutants of the protease in which the charges of these residues were neutralized by their substitutions with Ala (D185A, K186A, and E188A). Kinetic studies revealed that E188A has a normal catalytic activity toward small synthetic and natural substrates and inhibitors of fXa; however, the same activities were slightly ( approximately 2-fold) and dramatically ( approximately 20-50-fold) impaired for the D185A and K186A mutants, respectively. Further studies revealed that the affinity of D185A and K186A for interaction with Na(+) has also been altered, with a modest impairment ( approximately 2-fold) for the former and a dramatic impairment for the latter mutant. Both prothrombinase and direct binding studies indicated that K186A also has an approximately 6-fold impaired affinity for factor Va. Interestingly, a saturating concentration of factor Va restored the catalytic defect of K186A in reactions with prothrombin and the recombinant tick anticoagulant peptide that is known to interact with the Na(+) loop of fXa, but not with other substrates. These results suggest that factor Va interacts with 185-189-loop for fXa, which is energetically linked to the Na(+)-binding site of the protease.
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Affiliation(s)
- Alireza R Rezaie
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
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41
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Pineda AO, Carrell CJ, Bush LA, Prasad S, Caccia S, Chen ZW, Mathews FS, Di Cera E. Molecular dissection of Na+ binding to thrombin. J Biol Chem 2004; 279:31842-53. [PMID: 15152000 DOI: 10.1074/jbc.m401756200] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Na(+) binding near the primary specificity pocket of thrombin promotes the procoagulant, prothrombotic, and signaling functions of the enzyme. The effect is mediated allosterically by a communication between the Na(+) site and regions involved in substrate recognition. Using a panel of 78 Ala mutants of thrombin, we have mapped the allosteric core of residues that are energetically linked to Na(+) binding. These residues are Asp-189, Glu-217, Asp-222, and Tyr-225, all in close proximity to the bound Na(+). Among these residues, Asp-189 shares with Asp-221 the important function of transducing Na(+) binding into enhanced catalytic activity. None of the residues of exosite I, exosite II, or the 60-loop plays a significant role in Na(+) binding and allosteric transduction. X-ray crystal structures of the Na(+)-free (slow) and Na(+)-bound (fast) forms of thrombin, free or bound to the active site inhibitor H-d-Phe-Pro-Arg-chloromethyl-ketone, document the conformational changes induced by Na(+) binding. The slow --> fast transition results in formation of the Arg-187:Asp-222 ion pair, optimal orientation of Asp-189 and Ser-195 for substrate binding, and a significant shift of the side chain of Glu-192 linked to a rearrangement of the network of water molecules that connect the bound Na(+) to Ser-195 in the active site. The changes in the water network and the allosteric core explain the thermodynamic signatures linked to Na(+) binding and the mechanism of thrombin activation by Na(+). The role of the water network uncovered in this study establishes a new paradigm for the allosteric regulation of thrombin and other Na(+)-activated enzymes involved in blood coagulation and the immune response.
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Affiliation(s)
- Agustin O Pineda
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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42
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Abstract
After generation from prothrombin, thrombin plays multiple roles in the blood coagulation cascade that are mediated by interaction with a number of physiologic substrates, effectors, and inhibitors. Structural and mutagenesis studies have helped unravel the molecular basis of thrombin interactions in the context of both well-established and emerging new roles of the enzyme. The functional versatility of thrombin owes much to its evolutionary origin and results from structural determinants and mechanisms that can be exploited by pharmacologic intervention.
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Affiliation(s)
- Enrico Di Cera
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO 63110, USA.
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43
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Chen L, Yang L, Rezaie AR. Proexosite-1 on prothrombin is a factor Va-dependent recognition site for the prothrombinase complex. J Biol Chem 2003; 278:27564-9. [PMID: 12750382 DOI: 10.1074/jbc.m302707200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the contribution of basic residues of exosite-1 to the catalytic function of thrombin has been studied extensively, their role in the specificity of prothrombin recognition by factor Xa in the prothrombinase complex (factor Xa, factor Va, phosphatidylcholine/phosphatidylserine vesicles, and Ca2+) has not been examined. In this study, we prepared several mutants of prethrombin-1 (prothrombin lacking Gla and Kringle-1 domains) in which basic residues of this site (Arg35, Lys36, Arg67, Lys70, Arg73, Arg75, and Arg77 in chymotrypsinogen numbering) were individually substituted with a Glu. Following expression in mammalian cells and purification to homogeneity, these mutants were characterized with respect to their ability to function as zymogens for both factor Xa and the prothrombinase complex. Factor Xa by itself exhibited similar catalytic activity toward both the wild type and mutant substrates; however, its activity in the prothrombinase complex toward most of mutants was severely impaired. Further kinetic studies in the presence of Tyr63-sulfated hirudin-(54-65) peptide suggested that although the peptide inhibits the prothrombinase activation of the wild type zymogen with a KD of 0.5-0.7 microm, it is ineffective in inhibiting the activation of mutant zymogens (KD = 2-30 microm). These results suggest that basic residues of proexosite-1 on prothrombin are factor Va-dependent recognition sites for factor Xa in the prothrombinase complex.
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Affiliation(s)
- Lin Chen
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
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44
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Majumder R, Wang J, Lentz BR. Effects of water soluble phosphotidylserine on bovine factor Xa: functional and structural changes plus dimerization. Biophys J 2003; 84:1238-51. [PMID: 12547804 PMCID: PMC1302700 DOI: 10.1016/s0006-3495(03)74939-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Previous work has shown that two molecules of a soluble form of phosphatidylserine, C6PS, bind to human and bovine factor X(a). Activity measurements along with the fluorescence of active-site-labeled human factor X(a) showed that two linked sites specifically regulate the active site conformation and proteolytic activity of the human enzyme. These results imply, but cannot demonstrate, a C6PS-induced factor X(a) conformational change. The purpose of this paper is to extend these observations to bovine factor X(a) and to demonstrate that they do reflect conformational changes. We report that the fluorescence of active-site-labeled bovine factor X(a) also varied with C6PS concentration in a sigmoidal manner, whereas amidolytic activity of unlabeled enzyme varied in a simple hyperbolic fashion, also as seen for human factor X(a). C6PS induced a 70-fold increase in bovine factor X(a)'s autolytic activity, consistent with the 60-fold increase in proteolytic activity reported for human factor X(a). In addition, circular dichroism spectroscopy clearly demonstrated that C6PS binding to bovine factor X(a) induces secondary structural changes. In addition, C6PS binding to the tighter of the two sites triggered structural changes that lead to Ca(2+)-dependent dimer formation, as demonstrated by changes in intrinsic fluorescence and quantitative native gel electrophoresis. Dimerization produced further change in secondary structure, either inter- or intramolecularly. These results, along with results presented previously, support a model in which C6PS binds in a roughly sequential fashion to two linked sites whose occupancy in both human and bovine factor X(a) elicits different structural and functional responses.
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Affiliation(s)
- Rinku Majumder
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7260, USA
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45
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Camire RM. Prothrombinase assembly and S1 site occupation restore the catalytic activity of FXa impaired by mutation at the sodium-binding site. J Biol Chem 2002; 277:37863-70. [PMID: 12149252 DOI: 10.1074/jbc.m203692200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two loop segments (183-189 and 221-225) in the protease domain of factor Xa contribute to the formation of a Na(+)-binding site. Studies with factor Xa indicate that binding of a single Na(+) ion to this site influences its activity by altering the S1 specificity site, and substitution of Tyr(225) with Pro diminishes sensitivity to Na(+). Using full-length factor Xa(Y225P), the allosteric relationship between the Na(+) site and other structural determinants in factor Xa and prothrombinase was investigated. Direct binding and kinetic measurements with probes that target the S1 specificity pocket indicate that assembly of the mutant in prothrombinase corrected the impaired binding of these probes observed with free factor Xa(Y225P). This appears to result from the apparent allosteric linkage between the factor Va, S1, and Na(+)-binding sites, since binding of the cofactor to membrane-bound factor Xa(Y225P) enhances binding at the S1 site and vice versa. Additional studies revealed that the internal salt bridge (Ile(16)-Asp(194)) of factor Xa(Y225P) is partially destabilized, a process that is reversible upon occupation of the S1 site. The data establish that alterations at the factor Xa Na(+)-binding site shift the zymogen-protease equilibrium to a more zymogen-like state, and as a consequence binding of S1-directed probes and factor Va are adversely affected. Therefore, the zymogen-like characteristics of factor Xa(Y225P) have allowed for the apparent allosteric linkage between the S1, factor Va, and Na(+) sites to become evident and has provided insight into the structural transitions which accompany the conversion of factor X to factor Xa.
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Affiliation(s)
- Rodney M Camire
- Joseph Stokes, Jr. Research Institute, Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
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46
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Srivastava A, Wang J, Majumder R, Rezaie AR, Stenflo J, Esmon CT, Lentz BR. Localization of phosphatidylserine binding sites to structural domains of factor Xa. J Biol Chem 2002; 277:1855-63. [PMID: 11707438 DOI: 10.1074/jbc.m105697200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Binding of short chain phosphatidylserine (C6PS) enhances the proteolytic activity of factor X(a) by 60-fold (Koppaka, V., Wang, J., Banerjee, M., and Lentz, B. R. (1996) Biochemistry 35, 7482-7491). In the present study, we locate three C6PS binding sites to different domains of factor X(a) using a combination of activity, circular dichroism, fluorescence, and equilibrium dialysis measurements on proteolytic and biosynthetic fragments of factor X(a). Our results demonstrate that the structural responses of human and bovine factor X(a) to C6PS binding are somewhat different. Despite this difference, data obtained with fragments from both human and bovine factor X(a) are consistent with a common hypothesis for the location of C6PS binding sites to different structural domains. First, the gamma-carboxyglutamic acid (Gla) domain binds C6PS only in the absence of Ca(2+) (k(d) approximately 1 mm), although this PS site does not influence the functional response of factor X(a). Second, a Ca(2+)-dependent binding site is in the epidermal growth factor domains (EGF(NC)) that are linked by Ca(2+) and C6PS binding to the Gla domain. This site appears to be the lipid regulatory site of factor X(a). Third, a Ca(2+)-requiring site seems to be in the EGF(C)-catalytic domain. This site appears not to be a lipid regulatory site but rather to share residues with the substrate recognition site. Finally, the full functional response to C6PS requires linkage of the Gla, EGF(NC), and catalytic domains in the presence of Ca(2+), meaning that PS regulation of factor X(a) involves linkage between widely separated parts of the protein.
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Affiliation(s)
- Arvind Srivastava
- Department of Biochemistry & Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA
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47
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Rezaie AR, Yang L. Probing the molecular basis of factor Xa specificity by mutagenesis of the serpin, antithrombin. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1528:167-76. [PMID: 11687304 DOI: 10.1016/s0304-4165(01)00189-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The molecular basis of the substrate and inhibitor specificity of factor Xa, the serine proteinase of the prothrombinase complex, was investigated by constructing two mutants of human antithrombin (HAT) in which the reactive site loop of the serpin from the P4-P4' site was replaced with the corresponding residues of the two factor Xa cleavage sites in prothrombin (HAT/Proth-1 and HAT/Proth-2). These mutants together with prethrombin-2, the smallest zymogen form of thrombin containing only the second factor Xa cleavage site, were expressed in mammalian cells, purified to homogeneity and characterized in kinetic reactions with factor Xa in both the absence and presence of cofactors; factor Va, high affinity heparin and pentasaccharide fragment of heparin. HAT/Proth-1 inactivated factor Xa approximately 3-4-fold better than HAT/Proth-2 in either the absence or presence of heparin cofactors. In the absence of a cofactor, factor Xa reacted with the HAT/Proth-2 and prethrombin-2 with similar second-order rate constants (approximately 2-3x10(2) M(-1)s(-1)). Pentasaccharide catalyzed the inactivation rate of factor Xa by the HAT mutants 300-500-fold. A similar 10(4)-10(5)-fold enhancement in the reactivity of factor Xa with prethrombin-2 and the HAT mutants was observed in the presence of the cofactors Va and heparin, respectively. Factor Va did not influence the reactivity of factor Xa with either one of the HAT mutants. These results suggest that (1) in the absence of a cofactor, the P4-P4' residues of HAT and prethrombin-2 primarily determine the specificity reactions with factor Xa, (2) factor Va binding to factor Xa is not associated with allosteric changes in the catalytic pocket of enzyme that would involve interactions with the P4-P4' binding sites, and (3) similar to allosteric activation of HAT by heparin, a role for factor Va in the prothrombinase complex may involve rearrangement of the residues surrounding the scissile bond of the substrate to facilitate its optimal docking into the catalytic pocket of factor Xa.
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Affiliation(s)
- A R Rezaie
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, MO 63104, USA.
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48
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Abstract
The sodium binding to serine proteases triggers a conformational change in the proteins that enhances the catalytic activity of the enzymes. The interaction of the cation with the protein is mediated by the hydrogen-bonding network of water molecules that embed the Na+ site. We pointed out the crucial role of the insertion loop 186a-d and the I16-D194 ion pair in the stabilization of sodium binding pocket in thrombin. This paper contributes to better explain the molecular mechanism of sodium binding for different serine proteases leading to the identification of the structural changes necessary to engineer a functional Na+ site and regulate catalytic activity in serine proteases.
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Affiliation(s)
- N Griffon
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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Underwood MC, Zhong D, Mathur A, Heyduk T, Bajaj SP. Thermodynamic linkage between the S1 site, the Na+ site, and the Ca2+ site in the protease domain of human coagulation factor xa. Studies on catalytic efficiency and inhibitor binding. J Biol Chem 2000; 275:36876-84. [PMID: 10973949 DOI: 10.1074/jbc.m001386200] [Citation(s) in RCA: 46] [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
The serine protease domain of factor Xa (FXa) contains a sodium as well as a calcium-binding site. Here, we investigated the functional significance of these two cation-binding sites and their thermodynamic links to the S1 site. Kinetic data reveal that Na(+) binds to the substrate bound FXa with K(d) approximately 39 mm in the absence and approximately 9.5 mm in the presence of Ca(2+). Sodium-bound FXa (sodium-Xa) has approximately 18-fold increased catalytic efficiency ( approximately 4.5-fold decrease in K(m) and approximately 4-fold increase in k(cat)) in hydrolyzing S-2222 (benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide), and Ca(2+) further increases this k(cat) approximately 1.4-fold. Ca(2+) binds to the protease domain of substrate bound FXa with K(d) approximately 705 microm in the absence and approximately 175 microm in the presence of Na(+). Ca(2+) binding to the protease domain of FXa (Xa-calcium) has no effect on the K(m) but increases the k(cat) approximately 4-fold in hydrolyzing S-2222, and Na(+) further increases this k(cat) approximately 1.4-fold. In agreement with the K(m) data, sodium-Xa has approximately 5-fold increased affinity in its interaction with p-aminobenzamidine (S1 site probe) and approximately 4-fold increased rate in binding to the two-domain tissue factor pathway inhibitor; Ca(2+) (+/-Na(+)) has no effect on these interactions. Antithrombin binds to Xa-calcium with a approximately 4-fold faster rate, to sodium-Xa with a approximately 24-fold faster rate and to sodium-Xa-calcium with a approximately 28-fold faster rate. Thus, Ca(2+) and Na(+) together increase the catalytic efficiency of FXa approximately 28-fold. Na(+) enhances Ca(2+) binding, and Ca(2+) enhances Na(+) binding. Further, Na(+) enhances S1 site occupancy, and S1 site occupancy enhances Na(+) binding. Therefore, Na(+) site is thermodynamically linked to the S1 site as well as to the protease domain Ca(2+) site, whereas Ca(2+) site is only linked to the Na(+) site. The significance of these findings is that during physiologic coagulation, most of the FXa formed will exist as sodium-Xa-calcium, which has maximum biologic activity.
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Affiliation(s)
- M C Underwood
- Department of Biochemistry and Molecular Biology and the Departments of Medicine and Pathology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
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