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Lai Z, Li J, Zhou S, Wu X, Yuan J, Li F, Wu W, Ding Q, Dai J, Wang X, Lu Y, Cai X. Mutation Ter462GlnextTer17 introduces a tail to C-terminus of protein C and causes venous thrombosis. Thromb Res 2024; 240:109044. [PMID: 38824799 DOI: 10.1016/j.thromres.2024.109044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/23/2024] [Accepted: 05/28/2024] [Indexed: 06/04/2024]
Abstract
Protein C (PC), a vitamin K-dependent serine protease zymogen in plasma, can be activated by thrombin-thrombomodulin(TM) complex, resulting in the formation of activated protein C (APC). APC functions to downregulate thrombin generation by inactivating active coagulation factors V(FVa) and VIII(FVIIIa). Deficiency in PC increases the risk of venous thromboembolism (VTE). We have identified two unrelated VTE patients with the same heterozygous mutation (c.1384 T > C, p.Ter462GlnextTer17) in PROC. To comprehend the role of this mutation in VTE development, we expressed recombinant PC-Ter462GlnextTer17 in mammalian cells and evaluated its characteristics using established coagulation assay systems. Functional studies revealed a significant impairment in the activation of the mutant by thrombin or thrombin-TM complex. Furthermore, APC-Ter462GlnextTer17 demonstrated diminished hydrolytic activity towards the chromogenic substrate S2366. APTT and FVa degradation assays showed that both the anticoagulant activity of the mutant protein was markedly impaired, regardless of whether protein S was present or absent. These results were further supported by a thrombin generation assay conducted using purified and plasma-based systems. In conclusion, the Ter462GlnextTer17 mutation introduces a novel tail at the C-terminus of PC, leading to impaired activity in both PC zymogen activation and APC's anticoagulant function. This impairment contributes to thrombosis in individuals carrying this heterozygous mutation and represents a genetic risk factor for VTE.
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Affiliation(s)
- Zhe Lai
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jiaming Li
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Transfusion Department, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Shijie Zhou
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Xi Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Junwei Yuan
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Fang Li
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Wenman Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Qiulan Ding
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jing Dai
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Xuefeng Wang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
| | - Yeling Lu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
| | - Xiaohong Cai
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Transfusion Department, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
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2
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Stojanovski BM, Pelc LA, Di Cera E. Thrombin has dual trypsin-like and chymotrypsin-like specificity. J Thromb Haemost 2024; 22:1009-1015. [PMID: 38160728 PMCID: PMC10960677 DOI: 10.1016/j.jtha.2023.12.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/16/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND The residue at the site of activation of protein C is Arg in all species except the ray-finned fish, where it is Trp. This feature raises the question of whether thrombin is the physiological activator of protein C across vertebrates. OBJECTIVES To establish if thrombin can cleave at Trp residues. METHODS The activity of wild-type thrombin and mutant D189S was tested with a library of chromogenic substrates and toward wild-type protein C and mutants carrying substitutions at the site of cleavage. RESULTS Thrombin has trypsin-like and chymotrypsin-like specificity and cleaves substrates at Arg or Trp residues. Cleavage at Arg is preferred, but cleavage at Trp is significant and comparable with that of chymotrypsin. The D189S mutant of thrombin has broad specificity and cleaves at basic and aromatic residues without significant preference. Thrombin also cleaves natural substrates at Arg or Trp residues, showing activity toward protein C across vertebrates, including the ray-finned fish. The rate of activation of protein C in the ray-finned fish is affected by the sequence preceding Trp at the scissile bond. CONCLUSION The results provide a possible solution for the paradoxical presence of a Trp residue at the site of cleavage of protein C in ray-finned fish and support thrombin as the physiological activator of protein C in all vertebrates. The dual trypsin-like and chymotrypsin-like specificity of thrombin suggests that the spectrum of physiological substrates of this enzyme is broader currently assumed.
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Affiliation(s)
- Bosko M Stojanovski
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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3
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Rosenfeld MA, Yurina LV, Gavrilina ES, Vasilyeva AD. Post-Translational Oxidative Modifications of Hemostasis Proteins: Structure, Function, and Regulation. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:S14-S33. [PMID: 38621742 DOI: 10.1134/s0006297924140025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 09/01/2023] [Accepted: 09/05/2023] [Indexed: 04/17/2024]
Abstract
Reactive oxygen species (ROS) are constantly generated in a living organism. An imbalance between the amount of generated reactive species in the body and their destruction leads to the development of oxidative stress. Proteins are extremely vulnerable targets for ROS molecules, which can cause oxidative modifications of amino acid residues, thus altering structure and function of intra- and extracellular proteins. The current review considers the effect of oxidation on the structural rearrangements and functional activity of hemostasis proteins: coagulation system proteins such as fibrinogen, prothrombin/thrombin, factor VII/VIIa; anticoagulant proteins - thrombomodulin and protein C; proteins of the fibrinolytic system such as plasminogen, tissue plasminogen activator and plasminogen activator inhibitor-1. Structure and function of the proteins, oxidative modifications, and their detrimental consequences resulting from the induced oxidation or oxidative stress in vivo are described. Possible effects of oxidative modifications of proteins in vitro and in vivo leading to disruption of the coagulation and fibrinolysis processes are summarized and systematized, and the possibility of a compensatory mechanism in maintaining hemostasis under oxidative stress is analyzed.
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Affiliation(s)
- Mark A Rosenfeld
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia.
| | - Lyubov V Yurina
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Elizaveta S Gavrilina
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Alexandra D Vasilyeva
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia
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4
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Acquasaliente L, Pierangelini A, Pagotto A, Pozzi N, De Filippis V. From haemadin to haemanorm: Synthesis and characterization of full-length haemadin from the leech Haemadipsa sylvestris and of a novel bivalent, highly potent thrombin inhibitor (haemanorm). Protein Sci 2023; 32:e4825. [PMID: 37924304 PMCID: PMC10683372 DOI: 10.1002/pro.4825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/06/2023]
Abstract
Hirudin from Hirudo medicinalis is a bivalent α-Thrombin (αT) inhibitor, targeting the enzyme active site and exosite-I, and is currently used in anticoagulant therapy along with its simplified analogue hirulog. Haemadin, a small protein (57 amino acids) isolated from the land-living leech Haemadipsa sylvestris, selectively inhibits αT with a potency identical to that of recombinant hirudin (KI = 0.2 pM), with which it shares a common disulfide topology and overall fold. At variance with hirudin, haemadin targets exosite-II and therefore (besides the free protease) it also blocks thrombomodulin-bound αT without inhibiting the active intermediate meizothrombin, thus offering potential advantages over hirudin. Here, we produced in reasonably high yields and pharmaceutical purity (>98%) wild-type haemadin and the oxidation resistant Met5 → nor-Leucine analogue, both inhibiting αT with a KI of 0.2 pM. Thereafter, we used site-directed mutagenesis, spectroscopic, ligand-displacement, and Hydrogen/Deuterium Exchange-Mass Spectrometry techniques to map the αT regions relevant for the interaction with full-length haemadin and with the synthetic N- and C-terminal peptides Haem(1-10) and Haem(45-57). Haem(1-10) competitively binds to/inhibits αT active site (KI = 1.9 μM) and its potency was enhanced by 10-fold after Phe3 → β-Naphthylalanine exchange. Conversely to full-length haemadin, haem(45-57) displays intrinsic affinity for exosite-I (KD = 1.6 μM). Hence, we synthesized a peptide in which the sequences 1-9 and 45-57 were joined together through a 3-Glycine spacer to yield haemanorm, a highly potent (KI = 0.8 nM) inhibitor targeting αT active site and exosite-I. Haemanorm can be regarded as a novel class of hirulog-like αT inhibitors with potential pharmacological applications.
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Affiliation(s)
- Laura Acquasaliente
- Laboratory of Protein Chemistry & Molecular Hematology, Department of Pharmaceutical and Pharmacological Sciences, School of MedicineUniversity of PadovaPaduaItaly
| | - Andrea Pierangelini
- Laboratory of Protein Chemistry & Molecular Hematology, Department of Pharmaceutical and Pharmacological Sciences, School of MedicineUniversity of PadovaPaduaItaly
| | - Anna Pagotto
- Laboratory of Protein Chemistry & Molecular Hematology, Department of Pharmaceutical and Pharmacological Sciences, School of MedicineUniversity of PadovaPaduaItaly
| | - Nicola Pozzi
- Laboratory of Protein Chemistry & Molecular Hematology, Department of Pharmaceutical and Pharmacological Sciences, School of MedicineUniversity of PadovaPaduaItaly
- Department of Biochemistry and Molecular Biology, Edward A. Doisy Research CenterSaint Louis UniversitySt. LouisMissouriUSA
| | - Vincenzo De Filippis
- Laboratory of Protein Chemistry & Molecular Hematology, Department of Pharmaceutical and Pharmacological Sciences, School of MedicineUniversity of PadovaPaduaItaly
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5
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Ruben EA, Summers B, Rau MJ, Fitzpatrick JAJ, Di Cera E. Cryo-EM structure of the prothrombin-prothrombinase complex. Blood 2022; 139:3463-3473. [PMID: 35427420 PMCID: PMC9203702 DOI: 10.1182/blood.2022015807] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/30/2022] [Indexed: 11/23/2022] Open
Abstract
The intrinsic and extrinsic pathways of the coagulation cascade converge to a common step where the prothrombinase complex, comprising the enzyme factor Xa (fXa), the cofactor fVa, Ca2+ and phospholipids, activates the zymogen prothrombin to the protease thrombin. The reaction entails cleavage at 2 sites, R271 and R320, generating the intermediates prethrombin 2 and meizothrombin, respectively. The molecular basis of these interactions that are central to hemostasis remains elusive. We solved 2 cryogenic electron microscopy (cryo-EM) structures of the fVa-fXa complex, 1 free on nanodiscs at 5.3-Å resolution and the other bound to prothrombin at near atomic 4.1-Å resolution. In the prothrombin-fVa-fXa complex, the Gla domains of fXa and prothrombin align on a plane with the C1 and C2 domains of fVa for interaction with membranes. Prothrombin and fXa emerge from this plane in curved conformations that bring their protease domains in contact with each other against the A2 domain of fVa. The 672ESTVMATRKMHDRLEPEDEE691 segment of the A2 domain closes on the protease domain of fXa like a lid to fix orientation of the active site. The 696YDYQNRL702 segment binds to prothrombin and establishes the pathway of activation by sequestering R271 against D697 and directing R320 toward the active site of fXa. The cryo-EM structure provides a molecular view of prothrombin activation along the meizothrombin pathway and suggests a mechanism for cleavage at the alternative R271 site. The findings advance our basic knowledge of a key step of coagulation and bear broad relevance to other interactions in the blood.
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Affiliation(s)
- Eliza A Ruben
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
| | | | | | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging
- Department of Cell Biology and Physiology, and
- Department of Neuroscience, Washington University School of Medicine, St Louis, MO; and
- Department of Biomedical Engineering, Washington University in Saint Louis, St. Louis, MO
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO
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6
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Pelc LA, Koester SK, Kukla CR, Chen Z, Di Cera E. The active site region plays a critical role in Na + binding to thrombin. J Biol Chem 2022; 298:101458. [PMID: 34861239 PMCID: PMC8695361 DOI: 10.1016/j.jbc.2021.101458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 11/23/2022] Open
Abstract
The catalytic activity of thrombin and other enzymes of the blood coagulation and complement cascades is enhanced significantly by binding of Na+ to a site >15 Å away from the catalytic residue S195, buried within the 180 and 220 loops that also contribute to the primary specificity of the enzyme. Rapid kinetics support a binding mechanism of conformational selection where the Na+-binding site is in equilibrium between open (N) and closed (N∗) forms and the cation binds selectively to the N form. Allosteric transduction of this binding step produces enhanced catalytic activity. Molecular details on how Na+ gains access to this site and communicates allosterically with the active site remain poorly defined. In this study, we show that the rate of the N∗→N transition is strongly correlated with the analogous E∗→E transition that governs the interaction of synthetic and physiologic substrates with the active site. This correlation supports the active site as the likely point of entry for Na+ to its binding site. Mutagenesis and structural data rule out an alternative path through the pore defined by the 180 and 220 loops. We suggest that the active site communicates allosterically with the Na+ site through a network of H-bonded water molecules that embeds the primary specificity pocket. Perturbation of the mobility of S195 and its H-bonding capabilities alters interaction with this network and influences the kinetics of Na+ binding and allosteric transduction. These findings have general mechanistic relevance for Na+-activated proteases and allosteric enzymes.
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Affiliation(s)
- Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Sarah K Koester
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Cassandra R Kukla
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Zhiwei Chen
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA.
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7
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Stojanovski BM, Pelc LA, Zuo X, Di Cera E. Zymogen and activated protein C have similar structural architecture. J Biol Chem 2020; 295:15236-15244. [PMID: 32855236 PMCID: PMC7650249 DOI: 10.1074/jbc.ra120.014789] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/14/2020] [Indexed: 11/06/2022] Open
Abstract
Activated protein C is a trypsin-like protease with anticoagulant and cytoprotective properties that is generated by thrombin from the zymogen precursor protein C in a reaction greatly accelerated by the cofactor thrombomodulin. The molecular details of this activation remain elusive due to the lack of structural information. We now fill this gap by providing information on the overall structural organization of these proteins using single molecule FRET and small angle X-ray scattering. Under physiological conditions, both zymogen and protease adopt a conformation with all domains vertically aligned along an axis 76 Å long and maximal particle size of 120 Å. This conformation is stabilized by binding of Ca2+ to the Gla domain and is affected minimally by interaction with thrombin. Hence, the zymogen protein C likely interacts with the thrombin-thrombomodulin complex through a rigid body association that produces a protease with essentially the same structural architecture. This scenario stands in contrast to an analogous reaction in the coagulation cascade where conversion of the zymogen prothrombin to the protease meizothrombin by the prothrombinase complex is linked to a large conformational transition of the entire protein. The presence of rigid epidermal growth factor domains in protein C as opposed to kringles in prothrombin likely accounts for the different conformational plasticity of the two zymogens. The new structural features reported here for protein C have general relevance to vitamin K-dependent clotting factors containing epidermal growth factor domains, such as factors VII, IX, and X.
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Affiliation(s)
- Bosko M Stojanovski
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Xiaobing Zuo
- X-Ray Science Division, Argonne National Laboratory, Lemont, Illinois, USA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA.
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8
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Stojanovski BM, Pelc LA, Di Cera E. Role of the activation peptide in the mechanism of protein C activation. Sci Rep 2020; 10:11079. [PMID: 32632109 PMCID: PMC7338465 DOI: 10.1038/s41598-020-68078-z] [Citation(s) in RCA: 8] [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: 03/24/2020] [Accepted: 06/17/2020] [Indexed: 12/19/2022] Open
Abstract
Protein C is a natural anticoagulant activated by thrombin in a reaction accelerated by the cofactor thrombomodulin. The zymogen to protease conversion of protein C involves removal of a short activation peptide that, relative to the analogous sequence present in other vitamin K-dependent proteins, contains a disproportionately high number of acidic residues. Through a combination of bioinformatic, mutagenesis and kinetic approaches we demonstrate that the peculiar clustering of acidic residues increases the intrinsic disorder propensity of the activation peptide and adversely affects the rate of activation. Charge neutralization of the acidic residues in the activation peptide through Ala mutagenesis results in a mutant activated by thrombin significantly faster than wild type. Importantly, the mutant is also activated effectively by other coagulation factors, suggesting that the acidic cluster serves a protective role against unwanted proteolysis by endogenous proteases. We have also identified an important H-bond between residues T176 and Y226 that is critical to transduce the inhibitory effect of Ca2+ and the stimulatory effect of thrombomodulin on the rate of zymogen activation. These findings offer new insights on the role of the activation peptide in the function of protein C.
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Affiliation(s)
- Bosko M Stojanovski
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA.
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9
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Residues W215, E217 and E192 control the allosteric E*-E equilibrium of thrombin. Sci Rep 2019; 9:12304. [PMID: 31444378 PMCID: PMC6707225 DOI: 10.1038/s41598-019-48839-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 08/13/2019] [Indexed: 01/07/2023] Open
Abstract
A pre-existing, allosteric equilibrium between closed (E*) and open (E) conformations of the active site influences the level of activity in the trypsin fold and defines ligand binding according to the mechanism of conformational selection. Using the clotting protease thrombin as a model system, we investigate the molecular determinants of the E*-E equilibrium through rapid kinetics and X-ray structural biology. The equilibrium is controlled by three residues positioned around the active site. W215 on the 215-217 segment defining the west wall of the active site controls the rate of transition from E to E* through hydrophobic interaction with F227. E192 on the opposite 190-193 segment defining the east wall of the active site controls the rate of transition from E* to E through electrostatic repulsion of E217. The side chain of E217 acts as a lever that moves the entire 215-217 segment in the E*-E equilibrium. Removal of this side chain converts binding to the active site to a simple lock-and-key mechanism and freezes the conformation in a state intermediate between E* and E. These findings reveal a simple framework to understand the molecular basis of a key allosteric property of the trypsin fold.
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10
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De Filippis V, Pozzi N, Acquasaliente L, Artusi I, Pontarollo G, Peterle D. Protein engineering by chemical methods: Incorporation of nonnatural amino acids as a tool for studying protein folding, stability, and function. Pept Sci (Hoboken) 2018. [DOI: 10.1002/pep2.24090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Vincenzo De Filippis
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
| | - Nicola Pozzi
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
| | - Laura Acquasaliente
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
| | - Ilaria Artusi
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
| | - Giulia Pontarollo
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
| | - Daniele Peterle
- Laboratory of Protein Chemistry, Department of Pharmaceutical & Pharmacological SciencesUniversity of Padua Padua Italy
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11
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Chakraborty P, Acquasaliente L, Pelc LA, Di Cera E. Interplay between conformational selection and zymogen activation. Sci Rep 2018; 8:4080. [PMID: 29511224 PMCID: PMC5840343 DOI: 10.1038/s41598-018-21728-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 02/09/2018] [Indexed: 11/09/2022] Open
Abstract
Trypsin-like proteases are synthesized as zymogens and activated through a mechanism that folds the active site for efficient binding and catalysis. Ligand binding to the active site is therefore a valuable source of information on the changes that accompany zymogen activation. Using the physiologically relevant transition of the clotting zymogen prothrombin to the mature protease thrombin, we show that the mechanism of ligand recognition follows selection within a pre-existing ensemble of conformations with the active site accessible (E) or inaccessible (E*) to binding. Prothrombin exists mainly in the E* conformational ensemble and conversion to thrombin produces two dominant changes: a progressive shift toward the E conformational ensemble triggered by removal of the auxiliary domains upon cleavage at R271 and a drastic drop of the rate of ligand dissociation from the active site triggered by cleavage at R320. Together, these effects produce a significant (700-fold) increase in binding affinity. Limited proteolysis reveals how the E*-E equilibrium shifts during prothrombin activation and influences exposure of the sites of cleavage at R271 and R320. These new findings on the molecular underpinnings of prothrombin activation are relevant to other zymogens with modular assembly involved in blood coagulation, complement and fibrinolysis.
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Affiliation(s)
- Pradipta Chakraborty
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Laura Acquasaliente
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA
| | - Enrico Di Cera
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, 63104, USA.
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12
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Pontarollo G, Acquasaliente L, Peterle D, Frasson R, Artusi I, De Filippis V. Non-canonical proteolytic activation of human prothrombin by subtilisin from Bacillus subtilis may shift the procoagulant-anticoagulant equilibrium toward thrombosis. J Biol Chem 2017; 292:15161-15179. [PMID: 28684417 DOI: 10.1074/jbc.m117.795245] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/28/2017] [Indexed: 12/26/2022] Open
Abstract
Blood coagulation is a finely regulated physiological process culminating with the factor Xa (FXa)-mediated conversion of the prothrombin (ProT) zymogen to active α-thrombin (αT). In the prothrombinase complex on the platelet surface, FXa cleaves ProT at Arg-271, generating the inactive precursor prethrombin-2 (Pre2), which is further attacked at Arg-320-Ile-321 to yield mature αT. Whereas the mechanism of physiological ProT activation has been elucidated in great detail, little is known about the role of bacterial proteases, possibly released in the bloodstream during infection, in inducing blood coagulation by direct proteolytic ProT activation. This knowledge gap is particularly concerning, as bacterial infections are frequently complicated by severe coagulopathies. Here, we show that addition of subtilisin (50 nm to 2 μm), a serine protease secreted by the non-pathogenic bacterium Bacillus subtilis, induces plasma clotting by proteolytically converting ProT into active σPre2, a nicked Pre2 derivative with a single cleaved Ala-470-Asn-471 bond. Notably, we found that this non-canonical cleavage at Ala-470-Asn-471 is instrumental for the onset of catalysis in σPre2, which was, however, reduced about 100-200-fold compared with αT. Of note, σPre2 could generate fibrin clots from fibrinogen, either in solution or in blood plasma, and could aggregate human platelets, either isolated or in whole blood. Our findings demonstrate that alternative cleavage of ProT by proteases, even by those secreted by non-virulent bacteria such as B. subtilis, can shift the delicate procoagulant-anticoagulant equilibrium toward thrombosis.
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Affiliation(s)
- Giulia Pontarollo
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
| | - Laura Acquasaliente
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
| | - Daniele Peterle
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
| | - Roberta Frasson
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
| | - Ilaria Artusi
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
| | - Vincenzo De Filippis
- From the Department of Pharmaceutical and Pharmacological Sciences, University of Padua, via Marzolo 5, Padua 35131, Italy
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13
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Abstract
In addition to its procoagulant and proinflammatory functions mediated by cleavage of fibrinogen and PAR1, the trypsin-like protease thrombin activates the anticoagulant protein C in a reaction that requires the cofactor thrombomodulin and the endothelial protein C receptor. Once in the circulation, activated protein C functions as an anticoagulant, anti-inflammatory and regenerative factor. Hence, availability of a protein C activator would afford a therapeutic for patients suffering from thrombotic disorders and a diagnostic tool for monitoring the level of protein C in plasma. Here, we present a fusion protein where thrombin and the EGF456 domain of thrombomodulin are connected through a peptide linker. The fusion protein recapitulates the functional and structural properties of the thrombin-thrombomodulin complex, prolongs the clotting time by generating pharmacological quantities of activated protein C and effectively diagnoses protein C deficiency in human plasma. Notably, these functions do not require exogenous thrombomodulin, unlike other anticoagulant thrombin derivatives engineered to date. These features make the fusion protein an innovative step toward the development of protein C activators of clinical and diagnostic relevance.
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14
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Vogt AD, Chakraborty P, Di Cera E. Kinetic dissection of the pre-existing conformational equilibrium in the trypsin fold. J Biol Chem 2015. [PMID: 26216877 DOI: 10.1074/jbc.m115.675538] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structural biology has recently documented the conformational plasticity of the trypsin fold for both the protease and zymogen in terms of a pre-existing equilibrium between closed (E*) and open (E) forms of the active site region. How such plasticity is manifested in solution and affects ligand recognition by the protease and zymogen is poorly understood in quantitative terms. Here we dissect the E*-E equilibrium with stopped-flow kinetics in the presence of excess ligand or macromolecule. Using the clotting protease thrombin and its zymogen precursor prethrombin-2 as relevant models we resolve the relative distribution of the E* and E forms and the underlying kinetic rates for their interconversion. In the case of thrombin, the E* and E forms are distributed in a 1:4 ratio and interconvert on a time scale of 45 ms. In the case of prethrombin-2, the equilibrium is shifted strongly (10:1 ratio) in favor of the closed E* form and unfolds over a faster time scale of 4.5 ms. The distribution of E* and E forms observed for thrombin and prethrombin-2 indicates that zymogen activation is linked to a significant shift in the pre-existing equilibrium between closed and open conformations that facilitates ligand binding to the active site. These findings broaden our mechanistic understanding of how conformational transitions control ligand recognition by thrombin and its zymogen precursor prethrombin-2 and have direct relevance to other members of the trypsin fold.
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Affiliation(s)
- Austin D Vogt
- From the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104
| | - Pradipta Chakraborty
- From the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104
| | - Enrico Di Cera
- From the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104
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15
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Chahal G, Thorpe M, Hellman L. The Importance of Exosite Interactions for Substrate Cleavage by Human Thrombin. PLoS One 2015; 10:e0129511. [PMID: 26110612 PMCID: PMC4482499 DOI: 10.1371/journal.pone.0129511] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/08/2015] [Indexed: 11/18/2022] Open
Abstract
Thrombin is a serine protease of the chymotrypsin family that acts both as a procoagulant and as an anticoagulant by cleaving either factor VIII, factor V and fibrinogen or protein C, respectively. Numerous previous studies have shown that electropositive regions at a distance from the active site, so called exosites, are of major importance for the cleavage by human thrombin. Upstream of all the known major cleavage sites for thrombin in factor VIII, factor V and fibrinogen are clusters of negatively charged amino acids. To study the importance of these sites for the interaction with the exosites and thereby the cleavage by thrombin, we have developed a new type of recombinant substrate. We have compared the cleavage rate of the minimal cleavage site, involving only 8-9 amino acids (typically the P4-P4' positions) surrounding the cleavage site, with the substrates also containing the negatively charged regions upstream of the cleavage sites. The results showed that addition of these regions enhanced the cleavage rate by more than fifty fold. However, the enhancement was highly dependent on the sequence of the actual cleavage site. A minimal site that showed poor activity by itself could be cleaved as efficiently as an optimal cleavage site when presented together with these negatively charged regions. Whereas sites conforming closely to the optimal site were only minimally enhanced by the addition of these regions. The possibility to mimic this interaction for the sites in factor V and factor VIII by recombinant substrates, which do not have the same folding as the full size target, indicates that the enhancement was primarily dependent on a relatively simple electrostatic interaction. However, the situation was very different for fibrinogen and protein C where other factors than only charge is of major importance.
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Affiliation(s)
- Gurdeep Chahal
- Department of Cell and Molecular Biology, Uppsala University, BMC, Box 596, SE-751 24, Uppsala, Sweden
| | - Michael Thorpe
- Department of Cell and Molecular Biology, Uppsala University, BMC, Box 596, SE-751 24, Uppsala, Sweden
| | - Lars Hellman
- Department of Cell and Molecular Biology, Uppsala University, BMC, Box 596, SE-751 24, Uppsala, Sweden
- * E-mail:
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16
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Pelc LA, Chen Z, Gohara DW, Vogt AD, Pozzi N, Di Cera E. Why Ser and not Thr brokers catalysis in the trypsin fold. Biochemistry 2015; 54:1457-64. [PMID: 25664608 DOI: 10.1021/acs.biochem.5b00014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Although Thr is equally represented as Ser in the human genome and as a nucleophile is as good as Ser, it is never found in the active site of the large family of trypsin-like proteases that utilize the Asp/His/Ser triad. The molecular basis of the preference of Ser over Thr in the trypsin fold was investigated with X-ray structures of the thrombin mutant S195T free and bound to an irreversible active site inhibitor. In the free form, the methyl group of T195 is oriented toward the incoming substrate in a conformation seemingly incompatible with productive binding. In the bound form, the side chain of T195 is reoriented for efficient substrate acylation without causing steric clash within the active site. Rapid kinetics prove that this change is due to selection of an active conformation from a preexisting ensemble of reactive and unreactive rotamers whose relative distribution determines the level of activity of the protease. Consistent with these observations, the S195T substitution is associated with a weak yet finite activity that allows identification of an unanticipated important role for S195 as the end point of allosteric transduction in the trypsin fold. The S195T mutation abrogates the Na(+)-dependent enhancement of catalytic activity in thrombin, activated protein C, and factor Xa and significantly weakens the physiologically important allosteric effects of thrombomodulin on thrombin and of cofactor Va on factor Xa. The evolutionary selection of Ser over Thr in trypsin-like proteases was therefore driven by the need for high catalytic activity and efficient allosteric regulation.
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Affiliation(s)
- Leslie A Pelc
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine , St. Louis, Missouri 63104, United States
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17
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Wood DC, Pelc LA, Pozzi N, Wallisch M, Verbout NG, Tucker EI, Gruber A, Di Cera E. WEDGE: an anticoagulant thrombin mutant produced by autoactivation. J Thromb Haemost 2015; 13:111-4. [PMID: 25369995 PMCID: PMC4368433 DOI: 10.1111/jth.12774] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND The production of therapeutically relevant proteases typically involves activation of a zymogen precursor by external enzymes, which may raise regulatory issues about availability and purity. Recent studies of thrombin precursors have shown how to engineer constructs that spontaneously convert to the mature protease by autoactivation, without the need for external enzymes. OBJECTIVES Autoactivation is an innovative strategy that promises to simplify the production of proteases of therapeutic relevance, but has not been tested in practical applications. The aim of this study was to provide a direct test of this strategy. METHODS An autoactivating version of the thrombin mutant W215A/E217A (WE), which is currently in preclinical development as an anticoagulant, was engineered. RESULTS AND CONCLUSIONS The autoactivating version of WE can be produced in large quantities, like WE made in BHK cells or Escherichia coli, and retains all significant functional properties in vitro and in vivo. The results serve as proof of principle that autoactivation is an innovative and effective strategy for the production of trypsin-like proteases of therapeutic relevance.
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Affiliation(s)
- D C Wood
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
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18
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Landgraf KE, Steffek M, Quan C, Tom J, Yu C, Santell L, Maun HR, Eigenbrot C, Lazarus RA. An allosteric switch for pro-HGF/Met signaling using zymogen activator peptides. Nat Chem Biol 2014; 10:567-73. [DOI: 10.1038/nchembio.1533] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 04/17/2014] [Indexed: 12/17/2022]
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19
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Barranco-Medina S, Pozzi N, Vogt AD, Di Cera E. Histone H4 promotes prothrombin autoactivation. J Biol Chem 2013; 288:35749-57. [PMID: 24178300 DOI: 10.1074/jbc.m113.509786] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent studies have documented the ability of prothrombin to spontaneously convert to the mature protease thrombin when Arg-320 becomes exposed to solvent for proteolytic attack upon mutation of residues in the activation domain. Whether prothrombin autoactivation occurs in the wild-type under conditions relevant to physiology remains unknown. Here, we report that binding of histone H4 to prothrombin under physiological conditions generates thrombin by autoactivation. The effect is abrogated by mutation of the catalytic Ser-525 and requires the presence of the Gla domain. Fluorescence titrations document direct binding of histone H4 to prothrombin with an affinity in the low nm range. Stopped flow data and luminescence resonance energy transfer measurements indicate that the binding mechanism obeys conformational selection. Among the two conformations of prothrombin, collapsed and fully extended, histone H4 binds selectively to the collapsed form and induces a transition toward a new conformation where the distance between Ser-101 in kringle-1 and Ser-210 in kringle-2 increases by 13 Å. These findings confirm the molecular plasticity of prothrombin emerged from recent structural studies and suggest that different conformations of the inter-kringle linker domain determine the functional behavior of prothrombin. The results also broaden our mechanistic understanding of the prothrombotic phenotype observed during cellular damage due to the release of histones in the blood stream. Prothrombin autoactivation induced by histone H4 emerges as a mechanism of pathophysiological relevance through which thrombin is generated independently of activation of the coagulation cascade.
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Affiliation(s)
- Sergio Barranco-Medina
- From the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104
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20
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Pozzi N, Acquasaliente L, Frasson R, Cristiani A, Moro S, Banzato A, Pengo V, Scaglione GL, Arcovito A, De Cristofaro R, De Filippis V. β2 -Glycoprotein I binds to thrombin and selectively inhibits the enzyme procoagulant functions. J Thromb Haemost 2013; 11:1093-102. [PMID: 23578283 DOI: 10.1111/jth.12238] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Indexed: 08/31/2023]
Abstract
BACKGROUND This work was aimed at characterizing the interaction of β(2)-glycoprotein I (β(2)GPI), an abundant plasma protein of unknown function, with human thrombin, the final effector protease in the coagulation cascade. METHODS The β(2)GPI-thrombin interaction was studied by surface plasmon resonance (SPR), fluorescence, and molecular modeling. The effect of β(2)GPI on the procoagulant (fibrin generation and platelet aggregation) and anticoagulant (protein C activation) functions of thrombin were investigated with turbidimetric, immunocytofluorimetric and enzymatic assays. RESULTS SPR and fluorescence data indicated that β(2)GPI tightly bound thrombin (K(d) = 34 nM) by interacting with both protease exosites, while leaving the active site accessible. This picture is fully consistent with the theoretical model of the β(2)GPI-thrombin complex. In particular, blockage of thrombin exosites with binders specific for exosite-1 (hirugen and HD1 aptamer) or exosite-2 (fibrinogen γ'-peptide and HD22 aptamer) impaired the β2 GPI-thrombin interaction. Identical results were obtained with thrombin mutants having one of the two exosites selectively compromised by mutation (Arg73Ala and Arg101Ala). Fluorescence measurements indicated that β(2)GPI did not affect the affinity of the enzyme for active site inhibitors, such as p-aminobenzamidine and the hirudin(1-47) domain, in agreement with the structural model. β(2)GPI dose-dependently prolonged the thrombin clotting time and ecarin clotting time in β(2)GPI-deficient plasma. β(2)GPI inhibited thrombin-induced platelet aggregation (IC50 = 0.36 μM) by impairing thrombin cleavage of protease-activated receptor 1 (PAR1) (IC50 = 0.32 μM), both on gel-filtered platelets and in whole blood. Strikingly, β(2) GPI did not affect thrombin-mediated generation of the anticoagulant protein C. CONCLUSIONS β(2) GPI functions as a physiologic anticoagulant by inhibiting the key procoagulant activities of thrombin without affecting its unique anticoagulant function.
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Affiliation(s)
- N Pozzi
- Laboratory of Protein Chemistry, School of Medicine, University of Padua, Padova, Italy
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21
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Pozzi N, Chen Z, Zapata F, Niu W, Barranco-Medina S, Pelc LA, Di Cera E. Autoactivation of thrombin precursors. J Biol Chem 2013; 288:11601-10. [PMID: 23467412 DOI: 10.1074/jbc.m113.451542] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Trypsin-like proteases are synthesized as inactive zymogens and convert to the mature form upon activation by specific enzymes, often assisted by cofactors. Central to this paradigm is that the zymogen does not convert spontaneously to the mature enzyme, which in turn does not feed back to activate its zymogen form. In the blood, the zymogens prothrombin and prethrombin-2 require the prothrombinase complex to be converted to the mature protease thrombin, which is unable to activate prothrombin or prethrombin-2. Here, we show that replacement of key residues within the activation domain causes these zymogens to spontaneously convert to thrombin. The conversion is started by the zymogen itself, which is capable of binding ligands at the active site, and is abrogated by inactivation of the catalytic residue Ser-195. The product of autoactivation is functionally and structurally equivalent to wild-type thrombin. Zymogen autoactivation is explained by conformational selection, a basic property of the trypsin fold uncovered by structural and rapid kinetics studies. Both the zymogen and protease undergo a pre-existing equilibrium between active and inactive forms. The equilibrium regulates catalytic activity in the protease and has the potential to unleash activity in the zymogen to produce autoactivation. A new strategy emerges for the facile production of enzymes through zymogen autoactivation that is broadly applicable to trypsin-like proteases of biotechnological and clinical interest.
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Affiliation(s)
- Nicola Pozzi
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA
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Stavenuiter F, Bouwens EAM, Mosnier LO. Down-regulation of the clotting cascade by the protein C pathway. HEMATOLOGY EDUCATION. EUROPEAN HEMATOLOGY ASSOCIATION. CONGRESS. EDUCATION PROGRAM 2013; 7:365-374. [PMID: 24741378 PMCID: PMC3985519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The protein C pathway provides important biological activities to maintain the fluidity of the circulation, prevent thrombosis, and protect the integrity of the vasculature in response to injury. Activated protein C (APC), in concert with its cofactors and cell receptors, assembles in specific macromolecular complexes to provide efficient proteolysis of multiple substrates that result in anticoagulant and cytoprotective activities. Numerous studies on APC's structure-function relation with its cofactors, cell receptors, and substrates provide valuable insights into the molecular mechanisms and presumed assembly of the macromolecular complexes that are responsible for APC's activities. These insights allow for molecular engineering approaches specifically targeting the interaction of APC with one of its substrates or cofactors. Thus far, these approaches resulted in several anticoagulant-selective and cytoprotective-selective APC mutants, which provide unique insights into the relative contributions of APC's anticoagulant or cytoprotective activities to the beneficial effects of APC in various murine injury and disease models. Because of its multiple physiological and pharmacological activities, the anticoagulant and cytoprotective protein C pathway have important implications for the (patho)physiology of vascular disease and for translational research exploring novel therapeutic strategies to combat complex medical disorders such as thrombosis, inflammation, ischemic stroke and neurodegenerative disease.
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Abstract
In this issue of Blood, Pozzi et al demonstrate that removing an anionic cage promotes exposure of R169 thereby generating a protein C (PC) that is far more readily activated.
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