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Sarangi N, Shafaq-Zadah M, Berselli GB, Robinson J, Dransart E, Di Cicco A, Lévy D, Johannes L, Keyes TE. Galectin-3 Binding to α 5β 1 Integrin in Pore Suspended Biomembranes. J Phys Chem B 2022; 126:10000-10017. [PMID: 36413808 PMCID: PMC9743206 DOI: 10.1021/acs.jpcb.2c05717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Galectin-3 (Gal3) is a β-galactoside binding lectin that mediates many physiological functions, including the binding of cells to the extracellular matrix for which the glycoprotein α5β1 integrin is of critical importance. The mechanisms by which Gal3 interacts with membranes have not been widely explored to date due to the complexity of cell membranes and the difficulty of integrin reconstitution within model membranes. Herein, to study their interaction, Gal3 and α5β1 were purified, and the latter reconstituted into pore-suspended lipid bilayers comprised eggPC:eggPA. Using electrochemical impedance and fluorescence lifetime correlation spectroscopy, we found that on incubation with low nanomolar concentrations of wild-type Gal3, the membrane's admittance and fluidity, as well as integrin's lateral diffusivity, were enhanced. These effects were diminished in the following conditions: (i) absence of integrin, (ii) presence of lactose as a competitive inhibitor of glycan-Gal3 interaction, and (iii) use of a Gal3 mutant that lacked the N-terminal oligomerization domain (Gal3ΔNter). These findings indicated that WTGal3 oligomerized on α5β1 integrin in a glycan-dependent manner and that the N-terminal domain interacted directly with membranes in a way that is yet to be fully understood. At concentrations above 10 nM of WTGal3, membrane capacitance started to decrease and very slowly diffusing molecular species appeared, which indicated the formation of protein clusters made from WTGal3-α5β1 integrin assemblies. Overall, our study demonstrates the capacity of WTGal3 to oligomerize in a cargo protein-dependent manner at low nanomolar concentrations. Of note, these WTGal3 oligomers appeared to have membrane active properties that could only be revealed using our sensitive methods. At slightly higher WTGal3 concentrations, the capacity to generate lateral assemblies between cargo proteins was observed. In cells, this could lead to the construction of tubular endocytic pits according to the glycolipid-lectin (GL-Lect) hypothesis or to the formation of galectin lattices, depending on cargo glycoprotein stability at the membrane, the local Gal3 concentration, or plasma membrane intrinsic parameters. The study also demonstrates the utility of microcavity array-suspended lipid bilayers to address the biophysics of transmembrane proteins.
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Affiliation(s)
- Nirod
Kumar Sarangi
- School
of Chemical Sciences and National Centre for Sensor Research, Dublin City University, DCU Glasnevin Campus, D09 V209Dublin 9, Ireland
| | - Massiullah Shafaq-Zadah
- Institut
Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular
and Chemical Biology Unit, 75248Paris Cedex 05, France
| | - Guilherme B. Berselli
- School
of Chemical Sciences and National Centre for Sensor Research, Dublin City University, DCU Glasnevin Campus, D09 V209Dublin 9, Ireland
| | - Jack Robinson
- School
of Chemical Sciences and National Centre for Sensor Research, Dublin City University, DCU Glasnevin Campus, D09 V209Dublin 9, Ireland
| | - Estelle Dransart
- Institut
Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular
and Chemical Biology Unit, 75248Paris Cedex 05, France
| | - Aurélie Di Cicco
- Institut
Curie, PSL Research University, UMR 168 CNRS, 75248Paris Cedex 05, France
| | - Daniel Lévy
- Institut
Curie, PSL Research University, UMR 168 CNRS, 75248Paris Cedex 05, France
| | - Ludger Johannes
- Institut
Curie, PSL Research University, U1143 INSERM, UMR3666 CNRS, Cellular
and Chemical Biology Unit, 75248Paris Cedex 05, France,
| | - Tia E. Keyes
- School
of Chemical Sciences and National Centre for Sensor Research, Dublin City University, DCU Glasnevin Campus, D09 V209Dublin 9, Ireland,
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2
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Cohen CT, Turner NA, Moake JL. Human endothelial cells and fibroblasts express and produce the coagulation proteins necessary for thrombin generation. Sci Rep 2021; 11:21852. [PMID: 34750441 PMCID: PMC8575941 DOI: 10.1038/s41598-021-01360-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/26/2021] [Indexed: 11/09/2022] Open
Abstract
In a previous study, we reported that human endothelial cells (ECs) express and produce their own coagulation factors (F) that can activate cell surface FX without the additions of external proteins or phospholipids. We now describe experiments that detail the expression and production in ECs and fibroblasts of the clotting proteins necessary for formation of active prothrombinase (FV-FX) complexes to produce thrombin on EC and fibroblast surfaces. EC and fibroblast thrombin generation was identified by measuring: thrombin activity; thrombin-antithrombin complexes; and the prothrombin fragment 1.2 (PF1.2), which is produced by the prothrombinase cleavage of prothrombin (FII) to thrombin. In ECs, the prothrombinase complex uses surface-attached FV and γ-carboxyl-glutamate residues of FX and FII to attach to EC surfaces. FV is also on fibroblast surfaces; however, lower fibroblast expression of the gene for γ-glutamyl carboxylase (GGCX) results in production of vitamin K-dependent coagulation proteins (FII and FX) with reduced surface binding. This is evident by the minimal surface binding of PF1.2, following FII activation, of fibroblasts compared to ECs. We conclude that human ECs and fibroblasts both generate thrombin without exogenous addition of coagulation proteins or phospholipids. The two cell types assemble distinct forms of prothrombinase to generate thrombin.
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Affiliation(s)
- Clay T Cohen
- Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA.
| | - Nancy A Turner
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Joel L Moake
- Department of Bioengineering, Rice University, Houston, TX, USA
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Smith E, Vekaria R, Brown KA, Longstaff C. Kinetic regulation of the binding of prothrombin to phospholipid membranes. Mol Cell Biochem 2013; 382:193-201. [PMID: 23812842 PMCID: PMC3771376 DOI: 10.1007/s11010-013-1735-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/14/2013] [Indexed: 11/25/2022]
Abstract
A wide range of equilibrium and kinetic constants exist for the interaction of prothrombin and other coagulation factors with various model membranes from a variety of techniques. We have investigated the interaction of prothrombin with pure dioleoylphosphatidylcholine (DOPC) membranes and dioleoylphosphatidlyserine (DOPS)-containing membranes (DOPC:DOPS, 3:1) using surface plasmon resonance (SPR, with four different model membrane presentations) in addition to isotheral titration calorimetry (ITC, with suspensions of phospholipid vesicles) and ELISA methods. Using ITC, we found a simple low-affinity interaction with DOPC:DOPS membranes with a K(D) = 5.1 μM. However, ELISA methods using phospholipid bound to microtitre plates indicated a complex interaction with both DOPC:DOPS and DOPC membranes with K(D) values of 20 and 58 nM, respectively. An explanation for these discrepant results was developed from SPR studies. Using SPR with low levels of immobilised DOPC:DOPS, a high-affinity interaction with a K(D) of 18 nM was obtained. However, as phospholipid and prothrombin concentrations were increased, two distinct interactions could be discerned: (i) a kinetically slow, high-affinity interaction with K(D) in the 10(-8) M range and (ii) a kinetically rapid, low-affinity interaction with K(D) in the 10(-6 )M range. This low affinity, rapidly equilibrating, interaction dominated in the presence of DOPS. Detailed SPR studies supported a heterogeneous binding model in agreement with ELISA data. The binding of prothrombin with phospholipid membranes is complex and the techniques used to measure binding will report K D values reflecting the mixture of complexes detected. Existing data suggest that the weaker rapid interaction between prothrombin and membranes is the most important in vivo when considering the activation of prothrombin at the cell surface.
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Affiliation(s)
- Emma Smith
- Division of Cardiovascular and Diabetes Research, The LIGHT Laboratories, University of Leeds, Leeds, UK
| | | | - Katherine A. Brown
- Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712 USA
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE UK
| | - Colin Longstaff
- Biotherapeutics Section, National Institute for Biological Standards and Control, South Mimms, Hertfordshire EN6 3QG UK
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Thompson NL, Navaratnarajah P, Wang X. Measuring surface binding thermodynamics and kinetics by using total internal reflection with fluorescence correlation spectroscopy: practical considerations. J Phys Chem B 2010; 115:120-31. [PMID: 21166379 DOI: 10.1021/jp1069708] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The combination of total internal reflection illumination and fluorescence correlation spectroscopy (TIR-FCS) is an emerging method useful for, among a number of things, measuring the thermodynamic and kinetic parameters describing the reversible association of fluorescently labeled ligands in solution with immobilized, nonfluorescent surface binding sites. However, there are many parameters (both instrumental and intrinsic to the interaction of interest) that determine the nature of the acquired fluorescence fluctuation autocorrelation functions. In this work, we define criteria necessary for successful measurements and then systematically explore the parameter space to define conditions that meet the criteria. The work is intended to serve as a guide for experimental design, in other words, to provide a methodology to identify experimental conditions that will yield reliable values of the thermodynamic and kinetic parameters for a given interaction.
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Affiliation(s)
- Nancy L Thompson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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Macháň R, Hof M. Recent developments in fluorescence correlation spectroscopy for diffusion measurements in planar lipid membranes. Int J Mol Sci 2010; 11:427-457. [PMID: 20386647 PMCID: PMC2852847 DOI: 10.3390/ijms11020427] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/11/2010] [Accepted: 01/15/2010] [Indexed: 12/11/2022] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support.
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Affiliation(s)
- Radek Macháň
- J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i., Dolejškova 2155/3, 182 23 Prague, Czech Republic; E-Mail:
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i., Dolejškova 2155/3, 182 23 Prague, Czech Republic; E-Mail:
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Stefl M, Kułakowska A, Hof M. Simultaneous characterization of lateral lipid and prothrombin diffusion coefficients by z-scan fluorescence correlation spectroscopy. Biophys J 2009; 97:L01-3. [PMID: 19651025 DOI: 10.1016/j.bpj.2009.05.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 05/11/2009] [Accepted: 05/26/2009] [Indexed: 10/20/2022] Open
Abstract
A new (to our knowledge) robust approach for the determination of lateral diffusion coefficients of weakly bound proteins is applied for the phosphatidylserine specific membrane interaction of bovine prothrombin. It is shown that z-scan fluorescence correlation spectroscopy in combination with pulsed interleaved dual excitation allows simultaneous monitoring of the lateral diffusion of labeled protein and phospholipids. Moreover, from the dependencies of the particle numbers on the axial sample positions at different protein concentrations phosphatidylserine-dependent equilibrium dissociation constants are derived confirming literature values. Increasing the amount of membrane-bound prothrombin retards the lateral protein and lipid diffusion, indicating coupling of both processes. The lateral diffusion coefficients of labeled lipids are considerably larger than the simultaneously determined lateral diffusion coefficients of prothrombin, which contradicts findings reported for the isolated N-terminus of prothrombin.
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8
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Dasgupta SK, Thiagarajan P. Inhibition of thrombin activity by prothrombin activation fragment 1.2. J Thromb Thrombolysis 2007; 24:157-62. [PMID: 17334934 DOI: 10.1007/s11239-007-0018-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 02/01/2007] [Indexed: 10/23/2022]
Abstract
Prothrombin is the precursor of thrombin, the central enzyme in coagulation. Prothrombin is activated in vivo by the prothrombinase complex to form fragment 1.2 and thrombin. Fragment 1.2 has an amino-terminal gla domain and two kringle domains. The second kringle domain (kringle 2) binds to the exosite II on thrombin. Nascent thrombin generated on platelet surface remains non-covalently bound to fragment 1.2 by kringle 2-exosite II interaction. To determine whether this interaction can modulate coagulant activity of thrombin, we labeled thrombin at the active site with fluorescein-Phe-Pro-Arg chloromethylketone and monitored the fluorescence changes upon ligand binding. Anionic phospholipid-bound fragment 1.2 and fragment 2 bound to FPR-thrombin and induced changes in the active site with half maximal effects at 7.2 microM and 8.8 microM, respectively. We also tested the effect of anionic phospholipid-bound fragment 1.2 (0-10 microM) on thrombin clotting activity. Phospholipid-bound fragment 1.2 inhibited fibrinogen clotting in a concentration-dependent manner but had no significant effect on amidolytic activity towards S2238, suggesting a competitive inhibition of the fibrinogen binding site. Furthermore, fragment 1.2 inhibited FPR-thrombin binding to platelet. Consistent with these findings fragment 1.2 inhibited thrombin-induced aggregation of gel filtered platelets in a concentration-dependant manner. These results suggest that the membrane-bound prothrombin fragment 1.2 may play a role in hemostasis by down regulating the procoagulant activity of newly formed thrombin.
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Affiliation(s)
- Swapan Kumar Dasgupta
- Department of Pathology and Medicine (Thrombosis Research), Baylor College of Medicine, Michael E. DeBakey VA Medical Center, Houston, TX 77030, USA.
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9
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Wikström A, Deinum J. Probing the interaction of coagulation factors with phospholipid vesicle surfaces by surface plasma resonance. Anal Biochem 2006; 362:98-107. [PMID: 17239338 DOI: 10.1016/j.ab.2006.12.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 12/04/2006] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
The dynamics of the binding of human coagulation factor Xa (FXa) and prothrombin to small unilamellar vesicles (25% phosphatidylserine, 75% phosphatidylcholine) were compared and quantified by Biacore, using two immobilization techniques. The vesicles were either tagged with different molar ratios of cholesterol-DNA and attached on Au chips or fused directly on L1 chips. The diameter in solution was 145 nm, but the more DNA tags/vesicle the more compressed the immobilized vesicles became; with 30 DNA tags the calculated thickness was 88 nm and with 1 DNA tag it was 138 nm. In both models the affinity for the vesicles was higher for the activated coagulation factors than for the corresponding zymogens. FXa and prothrombin had the highest affinities. The affinity was dependent on the vesicle preparation since overall K(D) values were up to 10 times lower for N(2)-dried than for vacuum-dried phospholipids, although with apparently fewer binding sites. However, compression of the vesicles had no effect on the K(D). In contrast, the rate constants were dependent on the number of DNA tags; thus deformation of the vesicles was observed. The k(a) and k(d) for FXa were similar for vesicles attached with 30 DNA tags or fused on the L1 chip but higher with fewer tags and approximately 10 times higher if attached with 1 tag. Thus for controlled kinetic studies immobilized DNA-tagged vesicles should be used.
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Affiliation(s)
- Angelica Wikström
- Department of Applied Physics, Chalmers University of Technology, S-431 90 Göteborg, Sweden
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10
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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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11
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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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Hutterer R, Schneider FW, Hermens WT, Wagenvoord R, Hof M. Binding of prothrombin and its fragment 1 to phospholipid membranes studied by the solvent relaxation technique. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1414:155-64. [PMID: 9804936 DOI: 10.1016/s0005-2736(98)00163-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The phospholipid headgroup mobility of small unilamellar vesicles composed of different mixtures of phosphatidyl-L-serine (PS) and phosphatidylcholine is characterized by the solvent relaxation behavior of the polarity sensitive dyes 6-propionyl-2-(dimethylamino)naphthalene (Prodan) and 6-palmitoyl-2-[trimethylammoniumethyl]-methylamino]naphthalene chloride (Patman). If the PS content exceeds 10%, the addition of calcium leads to a substantial deceleration of the solvent relaxation of both dyes, indicating the formation of Ca(PS)2 complexes. Addition of prothrombin and its fragment 1 leads to a further decrease of the headgroup mobility, as explained by the binding of more than two PS-molecules by a single protein molecule. Prodan monitors the outermost region of the bilayer and it clearly distinguishes between the binding of prothrombin and its fragment 1. The deeper incalated Patman does not distinguish between both proteins. The validity of the solvent relaxation technique for the investigation of the membrane binding of peripheral proteins is demonstrated by the studies of prothrombin induced changes in the steady-state fluorescence anisotropies of 1,6-diphenyl-1,3, 5-hexatriene.
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Affiliation(s)
- R Hutterer
- Institute for Physical Chemistry, University of Würzburg, D-97074 Würzburg, Germany
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13
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Hof M. Picosecond tryptophan fluorescence of membrane-bound prothrombin fragment 1. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1388:143-53. [PMID: 9774720 DOI: 10.1016/s0167-4838(98)00174-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
The wavelength-dependent tryptophan (Trp) fluorescence decays of Ca-prothrombin fragment 1 (Ca-BF1), which contains three tryptophan residues, in the presence of pure phosphatidylcholine (PC) small unilamellar vesicles (SUV) and PC-SUV containing either 25% phosphatidyl-l-serine (PS), and 25% or 40% phosphatidylglycerol (PG) are characterized, using fluorescence lifetime distribution, conventional multiexponential, and global analysis. In analogy to previous investigations on apo- and Ca-BF1 (M. Hof, G.R. Fleming, V. Fidler, Proteins Struct. Func. Genet. 24 (1996) 485-494), the analysis resulted in a five exponential decay model in all investigated systems, where the five fluorescence lifetimes (e.g. 0. 04+/-0.02 ns (component A), 0.24+/-0.02 ns (B), 0.66+/-0.03 ns (C), 2.4+/-0.3 ns (D), and 5.4+/-0.4 ns (E) for Ca-BF1 in the presence of PC-SUV) are wavelength-independent. The fluorescence lifetimes and the corresponding amplitudes of the 'Gla-Trp' (components D and E) and of the two 'kringle-Trp' (components B, C, and D) remain unchanged when bound to the PS-containing vesicles. Saturation binding to PG-containing membranes leads to a prolongation of the Gla component E from 5.3 in solution to 7.5 ns, indicating a change in the Gla-domain conformation. The results represent the first experimental evidence of a lipid-specific conformational change in the N-terminal 'Gla domain' of a vitamin K-dependent protein.
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Affiliation(s)
- M Hof
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8, Czech Republic.
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14
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Thompson NL, Drake AW, Chen L, Vanden Broek W. Equilibrium, kinetics, diffusion and self-association of proteins at membrane surfaces: measurement by total internal reflection fluorescence microscopy. Photochem Photobiol 1997; 65:39-46. [PMID: 9066286 DOI: 10.1111/j.1751-1097.1997.tb01875.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The equilibrium, kinetics, diffusion and self-association of proteins at membrane/solution interfaces may deviate substantially from these processes in bulk solution. A set of methods for examining these phenomena combines substrate-supported planar model membranes and the use of evanescent illumination with laser-based, quantitative fluorescence microscopy. Measurement of the steady-state, surface-associated fluorescence can be used to examine the thermodynamic properties of proteins at membranes. When combined with fluorescence photobleaching recovery, this technique provides information about membrane-binding kinetics; and when combined with fluorescence pattern photobleaching recovery, measurement of the translational diffusion coefficients of proteins weakly bound to membranes is possible. The use of polarized evanescent illumination can provide information about the orientation distributions of adsorbed fluorophores. Fluorescence correlation spectroscopy provides information about the self-association (e.g. dimerization) of membrane-associated proteins.
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Affiliation(s)
- N L Thompson
- Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290, USA.
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15
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Evans TC, Nelsestuen GL. Importance of cis-proline 22 in the membrane-binding conformation of bovine prothrombin. Biochemistry 1996; 35:8210-5. [PMID: 8679575 DOI: 10.1021/bi9606354] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Upon addition of calcium to the metal-free protein, bovine prothrombin displays a conformational change with behavior of a classic trans- to cis-proline isomerization. The change is accompanied by a decrease of the intrinsic protein fluorescence and is essential to creating the membrane-binding conformation of prothrombin. This study showed that an identical conformational change was displayed by a peptide corresponding to residues 1-45 of prothrombin. This peptide contains a single tryptophan that underwent extensive quenching upon calcium addition. The kinetics were slow (t1/2 = 2.7 min at 24 degrees C) and displayed an activation energy of 24 kcal/mol. These properties overlapped precisely with the behavior of bovine prothrombin fragment 1 (residues 1-156). Consistent with studies on prothrombin and other vitamin K-dependent proteins that have been modified or truncated, the 1-45 peptide required about 10-fold higher calcium to elicit these behaviors than did fragment 1. The conformational change was necessary for membrane binding by the 1-45 peptide. The only proline in this sequence is at position 22. This proline is of the trans configuration in a crystallized form of calcium-bovine prothrombin fragment 1 [Soriano-Garcia, M., et al. (1992) Biochemistry 31, 2554]. Unless the protein conformational change is based on another behavior, this study showed that biochemical properties of the protein are inconsistent with structure solutions. Further studies are needed to reconcile structure/function in membrane association. Proline 22 in bovine prothrombin may constitute a useful biochemical marker for the membrane-binding conformation of a vitamin K-dependent protein.
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Affiliation(s)
- T C Evans
- Department of Biochemistry, University of Minnesota, St. Paul, 55108, USA
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16
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Lu Y, Nelsestuen GL. Dynamic features of prothrombin interaction with phospholipid vesicles of different size and composition: implications for protein--membrane contact. Biochemistry 1996; 35:8193-200. [PMID: 8679573 DOI: 10.1021/bi960280o] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The dynamics of prothrombin interaction with membrane vesicles of different size and composition was investigated to ascertain the impact of membrane surface characteristics and particle size on this interaction. Dissociation rates were highly sensitive to membrane composition and varied from about 20/s for membranes of 10% PS to 0.1/s for membranes of 50% PS. Overall affinity also varied by more than two orders of magnitude. Very small differences between prothrombin binding to SUV versus LUV were found. Association with large unilamellar vesicles (LUV of 115 nm diameter) was about 4-fold slower, when expressed on the basis of binding sites, than association with small unilamellar vesicles (SUV, 30 nm diameter) of the same composition. Both reactions proceeded at less than 25% of the collisional limit so that the differences were largely due to intrinsic binding properties. Vesicles of 325 nm diameter showed even slower association velocities. Dissociation rates from LUV were about 2-fold slower than from SUV. Again, these differences arose primarily from intrinsic binding properties. Dissociation conformed to a single first order reaction over a wide range of protein occupancy on the membrane. At very high packing density, the dissociation rate increased by about 2-fold. At equilibrium, prothrombin preferred binding to SUV over LUV by about 2-fold. This very small difference, despite substantial differences in phospholipid headgroup packing and hydrocarbon exposure, appeared inconsistent with an important role for protein insertion into the hydrocarbon region of the membrane. However, prothrombin-membrane interaction may arise from a series of interaction forces that have compensating features at equilibrium. The small differences in prothrombin binding to SUV versus LUV, together with differences in the number of protein binding sites per vesicle, were important to identify mechanisms of substrate delivery to the active site of the prothrombinase enzyme [Lu, Y., & Nelsestuen, G. L. (1996) Biochemistry 35, 8201-8209].
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Affiliation(s)
- Y Lu
- Department of Biochemistry, University of Minnesota, St. Paul, 55108, USA
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Lu Y, Nelsestuen GL. The prothrombinase reaction: "mechanism switching" between Michaelis-Menten and non-Michaelis-Menten behaviors. Biochemistry 1996; 35:8201-9. [PMID: 8679574 DOI: 10.1021/bi960281g] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Kinetic properties of prothrombinase were investigated as a function of composition and structure of the membrane component. The kinetic properties were quite diverse, giving linear or nonlinear Eadie-Hofstee plots and substrate concentrations at half-maximum velocity ([S]0.5) that varied from 5 to more than 200 nM. This reaction might be described as a "catalytic system" in order to distinguish it from standard models that have been developed to describe the kinetics of soluble enzymes. The latter do not anticipate a key feature of prothrombinase and probably other membrane-bound enzymes, which is the presence of reaction steps that do not contain an enzyme (E) term. At least four kinetic mechanisms can arise from a logical series of steps that may occur during the prothrombinase reaction. All of these mechanisms appeared to contribute to reaction properties under some conditions. In some cases, one mechanism dominated at low substrate concentration and another at high substrate concentration. This change in the course of a titration was referred to as "mechanism switching". Only membranes of low phosphatidylserine (PS) content displayed Michaelis-Menten behavior. Transfer of substrate from the membrane surface to the enzyme was not important so that the enzyme was involved in capture of substrate directly from solution. As PS content increased, transfer of substrate from the membrane surface to the enzyme occurred. In these cases, multiple mechanisms contributed to the reaction so that K(M) and apparent K(M), properties that describe an enzyme active site, were not appropriate, even when Eadie-Hofstee plots were linear. At high PS content, the enzyme captured every substrate molecule that became bound to the same vesicle. Reaction velocity was governed entirely by protein-membrane binding rather than by enzyme properties. Eadie-Hofstee plots were often nonlinear and/or V(max) was less than kcat[E1]. A small impact from collision-limited kinetics was also detected. Small unilamellar vesicles (SUV, 30 nm diameter) gave higher [S]0.5 values than large unilamellar vesicles (LUV, 100 nm diameter) of the same phospholipid composition. There appeared to be two bases for this behavior. First, LUV may provide a better relationship between the phospholipid surface and the enzyme, giving a better substrate binding site. Second, for membranes containing high PS, the number of substrate binding sites per vesicle contributed to the enhanced function of LUV. These studies showed that mechanism-switching was important to prothrombinase reaction in vitro and suggest that various mechanisms, generated by the nature of the membrane, may be an important regulator for prothrombinase behavior in vivo.
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Affiliation(s)
- Y Lu
- Department of Biochemistry, University of Minnesota, St. Paul, 55108, USA
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Lentz BR, Zhou CM, Wu JR. Phosphatidylserine-containing membranes alter the thermal stability of prothrombin's catalytic domain: a differential scanning calorimetric study. Biochemistry 1994; 33:5460-8. [PMID: 8180168 DOI: 10.1021/bi00184a015] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Denaturation profiles of bovine prothrombin and its isolated fragments were examined in the presence of Na2EDTA, 5 mM CaCl2, and CaCl2 plus membranes containing 1-palmitoyl-2-oleoyl-3-sn-phosphatidylcholine (POPC) in combination with bovine brain phosphatidylserine (PS). We have shown previously [Lentz, B. R., Wu, J. R., Sorrentino, A. M., & Carleton, J. A. (1991) Biophys. J. 60, 70] that binding to PS/POPC (25/75) large unilamellar vesicles resulted in an enthalpy loss in the main endotherm of prothrombin denaturation (Tm approximately 57-58 degrees C) and a comparable enthalpy gain in a minor endotherm (Tm approximately 59 degrees C) accompanying an upward shift in peak temperature (Tm approximately 73 degrees C). This minor endotherm was also responsive to Ca2+ binding and, in the absence of PS/POPC membranes, corresponded to melting of the N-terminal, Ca2+ and membrane binding domain (fragment 1). Peak deconvolution analysis of the prothrombin denaturation profile and extensive studies of the denaturation of isolated prothrombin domains in the presence and absence of PS/POPC vesicles suggested that membrane binding induced changes in the C-terminal catalytic domain of prothrombin (prethrombin 2) and in a domain that links fragment 1 with the catalytic domain (fragment 2). Specifically, the results have confirmed that the fragment 2 domain interacts with the stabilizes the prethrombin 2 domain and also have shown that fragment 2 interacts directly with the membrane. In addition, the results have demonstrated a heretofore unrecognized interaction between the catalytic and membrane binding domains. This interaction can account for another portion of the denaturation enthalpy that appears at high temperatures in the presence of membranes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- B R Lentz
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill 27599-7260
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Thompson NL, Pearce KH, Hsieh HV. Total internal reflection fluorescence microscopy: application to substrate-supported planar membranes. EUROPEAN BIOPHYSICS JOURNAL : EBJ 1993; 22:367-78. [PMID: 8112222 DOI: 10.1007/bf00213560] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The use of total internal reflection illumination in fluorescence microscopy (TIRFM) is reviewed with emphasis on application to fluorescent macromolecules that specifically and reversibly bind to planar model membranes supported on glass or quartz substrates. Several methods for characterizing macromolecular motion and organization are discussed: the measurement of equilibrium binding curves to obtain values for equilibrium binding constants; the measurement of fluorescence photobleaching recovery curves to obtain values of kinetic rate constants and surface diffusion coefficients; and the measurement of fluorescence intensities as a function of the evanescent field polarization to characterize orientational order. Applications to cell-substrate contact regions are summarized and future directions of TIRFM are outlined.
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Affiliation(s)
- N L Thompson
- Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290
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