scholarly journals Structural Determinants for Heparin Binding in Human Coagulation Factor XI.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2705-2705
Author(s):  
Sergei Shikov ◽  
Wenman Wu ◽  
Peter N. Walsh
Keyword(s):  
Catalytic Domain ◽  
Mutational Analysis ◽  
Solid Phase ◽  
Coagulation Factor ◽  
Hek293 Cells ◽  
Heparin Binding ◽  
Factor Xi ◽  
Dimeric Structure ◽  
Charged Residues ◽  
Positively Charged

Abstract Previous studies from our laboratory and others have demonstrated that zymogen factor XI (FXI) binds to heparin with moderate (KD ∼110 nM) affinity via residues (K252, K253 and K255) located in the Apple 3 (A3) domain. In contrast, the enzyme, FXIa, was shown to bind to heparin (Biochemistry40: 7569–7580, 2001) with significantly higher affinity (KD ∼9 nM by SPR and ∼1.5 nM by ELISA) via residues (K529, R530 and R532) within the catalytic domain (CD). This interaction potentiates by ∼10-fold the inhibition of FXIa by protease nexin-2. Also, polyanions heparin and dextran sulfate inhibit the catalytic activity of the enzyme factor XIa. The present study was designed to determine the relative contributions of positively charged residues as well as the dimeric structure of FXI to heparin binding. Mutational analysis of full-length FXI expressed in HEK293 cells was based on the following criteria: Conservation of the positively charged residues in FXI among various species; Surface exposure of the residues based on the X-ray crystal structure of FXI (Papagrigoriou E, McEwan P, Walsh PN, Emsley J,Nat. Struct. & Mol. Biol. 2006; 13:557–558); and comparison with human plasma prekallikrein (PK), which does not bind heparin. Two positively charged residues Arg507 (147, chymotrypsin numbering) and Arg532 (173) are conserved in FXI genes of all species for which sequences are available. In human PK, Arg507 is replaced by lysine, while Arg532 is replaced by a neutral glutamine. We have expressed and purified wtFXI, R507A, R532A as well as monomeric C321S/K331A and C321A/I290A. While wtFXI, R507A and R532A demonstrated normal activity in APTT assays; monomeric FXI mutants retained 60-70% activity. The R532A and R507A mutants demonstrated ∼75% decrease in total number of heparin binding sites based on the solid phase ELISA assay using 5F7 monoclonal antibody. Also, the apparent dissociation constants for R507 (11 nM) and R532A (22 nM) were 7 and 11-fold increased respectively compared with 1.6 nM for the wtFXI. We also characterized monomeric FXI C321S/K331A and C321A/I290A proteins for their ability to bind to heparin compared with wtFXI using surface plasmon resonance (SPR). Surprisingly, the monomeric FXI mutants, C321S/K331A and C321A/I290A, which had no mutations in any heparin-binding regions, displayed major defects in binding to heparin by SPR. Although kinetic analysis is challenging due to complex binding kinetics, while Rmax is about 10-fold lower, the off-rate for the binding of the monomeric FXI mutants is drastically increased when compared to that of wtFXI. These results suggest the possibility that the unique dimeric structure of FXI is required for cooperative binding to heparin. Thus, the dimeric structure of FXI and basic residues R507 and R532 in the catalytic domain of factor XI are both necessary for high-affinity heparin binding.

Chemical Footprinting Reveals Conformational Changes Following Activation of Factor XI

2018 ◽  
Vol 118 (02) ◽  
pp. 340-350 ◽  
Author(s):  
Ingrid Stroo ◽  
J. Marquart ◽  
Kamran Bakhtiari ◽  
Tom Plug ◽  
Alexander Meijer ◽  
...  
Keyword(s):  
Conformational Change ◽  
Conformational Changes ◽  
Catalytic Domain ◽  
Active Form ◽  
Coagulation Factor ◽  
Lysine Residue ◽  
Factor Ix ◽  
Factor Xi ◽  
Lysine Residues ◽  
Factor Xia

AbstractCoagulation factor XI is activated by thrombin or factor XIIa resulting in a conformational change that converts the catalytic domain into its active form and exposing exosites for factor IX on the apple domains. Although crystal structures of the zymogen factor XI and the catalytic domain of the protease are available, the structure of the apple domains and hence the interactions with the catalytic domain in factor XIa are unknown. We now used chemical footprinting to identify lysine residue containing regions that undergo a conformational change following activation of factor XI. To this end, we employed tandem mass tag in conjunction with mass spectrometry. Fifty-two unique peptides were identified, covering 37 of the 41 lysine residues present in factor XI. Two identified lysine residues that showed altered flexibility upon activation were mutated to study their contribution in factor XI stability or enzymatic activity. Lys357, part of the connecting loop between A4 and the catalytic domain, was more reactive in factor XIa but mutation of this lysine residue did not impact on factor XIa activity. Lys516 and its possible interactor Glu380 are located in the catalytic domain and are covered by the activation loop of factor XIa. Mutating Glu380 enhanced Arg369 cleavage and thrombin generation in plasma. In conclusion, we have identified novel regions that undergo a conformational change following activation. This information improves knowledge about factor XI and will contribute to development of novel inhibitors or activators for this coagulation protein.

The Disulfide Bond between Cys22 and Cys27 in the Protease Domain Modulate Clotting Activity of Coagulation Factor X

2019 ◽  
Vol 119 (06) ◽  
pp. 871-881 ◽  
Author(s):  
Fang Li ◽  
Changming Chen ◽  
Si-Ying Qu ◽  
Ming-Zhu Zhao ◽  
Xiaoling Xie ◽  
...  
Keyword(s):  
Disulfide Bond ◽  
Catalytic Domain ◽  
Coagulation Factor ◽  
Major Change ◽  
Coagulation Factors ◽  
Hek293 Cells ◽  
Factor X ◽  
Wild Type ◽  
Protease Domain ◽  
Dynamic Simulations

AbstractThe Cys22-Cys27 disulfide bond of factor X (FX) protease domain is not conserved among coagulation factors and its contribution to the physiological haemostasis and implication in the pathogenesis of haemostatic and thrombotic disorders remain to be elucidated. Mutation p.Cys27Ser was identified in a pedigree of congenital FX deficiency and fluorescence labelling study of transiently transfected HEK293 cells showed accumulation of FX p.Cys27Ser within cell, indicating incompetent secretion partially responsible for the FX deficiency. The clotting activity of FX p.Cys27Ser was decreased to about 90% of wild-type, while amidolytic and pro-thrombinase activities (kcat/Km) determined with recombinant FXa mutant were 1.33- and 4.77-fold lower. Molecular dynamic simulations revealed no major change in global structure between FXa p.Cys27Ser and wild-type FXa; however, without the Cys22-Cys27 disulfide bond, the insertion of newly formed N terminal of catalytic domain after the activation cleavage is hindered, perturbing the conformation transition from zymogen to enzyme. The crystal structure of FXa shows that this disulfide bond is solvent accessible, indicating that its stability might be subject to the oxidation/reduction balance. As demonstrated with FX p.Cys27Ser here, Cys22-Cys27 disulfide bond may modulate FX clotting activity, with reduced FX pertaining less pro-coagulant activity.

ISOLATION AND FUNCTIONAL PROPERTIES OF MONOMERIC BLOOD COAGULATION FACTOR XI

1987 ◽  
Author(s):  
M Berrettini ◽  
M J Heeb ◽  
J H Griffin
Keyword(s):  
Blood Coagulation ◽  
Gel Filtration ◽  
Coagulation Factor ◽  
Fluid Phase ◽  
Factor Ix ◽  
Contact Activation ◽  
Factor Xi ◽  
Dimeric Structure ◽  
Sds Page ◽  
Mild Reduction

To evaluate the significance of the normal dimeric structure (160,000 MW) of blood coagulation Factor XI (F.XI), a monomeric form (80,000 MW) was produced by mild reduction and alkylation of native F.XI. Since initial efforts to reduce and alkylate F.XI in solution inactivated the molecule, F.XI was bound to high MW kininogen (HMWK) to stabilize the native structure. Purified F.XI was bound to HMWK-Sepharose, and the column was washed for 2 h with 40 μM dithiothreitol in 4mM acetate buffer, 2mM EDTA, 1mM benzamidine, pH 7.8, and then for 2 h with 50 μM iodoacetamide in the same buffer. Elution with 0.5 M NaCl gave a preparation containing ∼ 85% F.XI monomer and ∼ 15% dimer, as judged by nonreduced SDS-PAGE and by gel filtration of the radiolabeled preparation. The monomeric F.XI preparation had only 10% of the clotting activity of dimeric F.XI (per mole of enzymatic site) as measured in APTT clotting assays using F.XI deficient plasma. After activation with β-Factor XIIa in solution, the monomer F.XIa preparation exhibited 85% of the clotting activity of native F.XIa in unactivated PTT assays using F.XI deficient plasma. In addition, when compared to native F.XIa, monomeric F.XIa gave 65% amidolytic activity against the substrate, S-2366, and 75% activity against Factor IX in assays of the release of the activation peptide from 3H-Factor IX. Polystyrene tubes were coated with HMWK then blocked with 1% BSA to study the binding of 125I-F.XI to HWMK. When the binding of the 125I-labeled preparations of monomeric and dimeric forms of F.XI to HMWK was studied, two distinct components were identified in the association of dimeric F.XI, one with high affinity (Kd ∼ 2.5 X 10-9M) and one with less affinity (Kd ∼ 1.7 X 10-8M), while the binding of monomeric F.XI occurred with a single low affinity component (Kd ∼ 1.1 X 10-8M). These observations suggest that the dimeric structure of F.XI is required for efficient binding of the molecule to HMWK and for normal activation by the contact activation system in plasma, but that the dimeric structure of F.XIa does not play a role in the expression of the enzymatic activity against Factor IX in fluid phase.

The Interaction of Coagulation Factor XI with Polyphosphate

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 498-498
Author(s):  
Yipeng Geng ◽  
Ingrid M. Verhamme ◽  
Qiufang Cheng ◽  
Anton Matafonov ◽  
Stephen B. Smith ◽  
...  
Keyword(s):  
Ferric Chloride ◽  
Conformational Changes ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Coagulation Factor ◽  
Wild Type ◽  
Zymogen Activation ◽  
Factor Xi ◽  
Dimeric Structure

Abstract Abstract 498 The plasma zymogen factor XI (FXI) is a homodimer of 80 kDa subunits. During blood coagulation, each subunit is activated by cleavage of the Arg369-Ile370 bond by factor XIIa (FXIIa) or thrombin. Initially, one subunit of the FXI dimer is activated to create the species 1/2FXIa, followed by activation of the second subunit, generating FXIa. Initial rates of activation of the first subunit are relatively low (∼8000 M−1.sec−1 for FXIIa and 120 M−1.sec−1 for thrombin). Rates for activation of the second subunit are even lower (1200 M−1.sec−1 for FXIIa and 35 M−1.sec−1 for thrombin), suggesting that conformational changes accompanying activation of a subunit reduce the efficiency of activation of its partner. The slow rate of FXI activation in solution strongly suggests that a cofactor is required for protease activation in vivo. FXI activation by FXIIa or thrombin is enhanced by polyanions such as dextran sulfate (DS). In addition, polyanions induce FXI activation by FXIa (autoactivation). Polymers of inorganic phosphate (polyP) released from platelet dense granules accelerate FXI activation by thrombin or FXIa (Blood 2011;118:6963), and likely represent the physiologic counterpart to DS. PolyP (4 μM) increased the initial rate of FXI activation by FXIIa ∼30-fold (300,000 M−1.sec−1), and by a-thrombin ∼3600-fold (440,000 M−1.sec−1). Furthermore, polyP induced FXI autoactivation in a manner similar to DS. Each FXI subunit contains two polyanion binding sites (residues Arg250, Lys252, Lys253, Lys255 on the A3 domain, and Lys529, Arg530, Arg532 on the catalytic domain). Both sites bind heparin, and are required for normal heparin-mediated enhancement of FXIa inhibition by antithrombin. FXI lacking the A3 domain site (FXIΔA3), but not FXI lacking the protease domain site (FXIΔCD), is activated slowly in the presence of DS compared to wild type FXI (FXIWT). Interestingly, both FXIΔA3 and FXIΔCD are activated slowly compared to FXIWT in the presence of polyP, and a species lacking both sites (FXIΔA3/CD) has an even greater defect, indicating FXI's interaction with polyP is different from its interaction with DS. The FXI gene arose from a duplication of the gene for the monomeric protein prekallikrein (PK). The observations that the dimeric structure of FXI is highly conserved across species, and that the ancestral molecule is a monomer, strongly indicate that the dimer is important for a specific aspect of FXI function. It was recently reported that monomeric forms of FXI are activated slowly compared to dimeric FXI in solution or in the presence of DS (J Biol Chem 2008;283:18655). FXI dimer formation is mediated through a hydrophobic interface involving Leu284, Ile290, and Tyr329, and an interchain disulfide bond involving Cys321. A Ser substitution for Cys321 in combination with an Ala substitution for Leu284 or Ile290 results in the monomeric species FXIC321S, L284A and FXIC321S, I290A. Rates of FXIC321S, L284A or FXIC321S, I290A activation by FXIIa were significantly lower than for FXIWT in the presence of polyP. However, this defect was not observed during activation by thrombin or FXIa, demonstrating that the dimeric structure is not a prerequisite for zymogen activation on polyP. FXI-deficient (FXI−/−) mice are more resistant to arterial thrombus formation induced by vessel injury with ferric chloride than are wild type mice. FXIWT, FXIC321S, L284A and FXIC321S, I290A were transiently expressed in FXI−/− mice by hydrodynamic tail vein injection. While the three proteins were expressed at comparable levels, only FXIWT completely reconstituted the wild type phenotype in the ferric chloride thrombosis model. In summary, polyP is a strong candidate for a cofactor to support FXI activation in vivo. The interaction of FXI with this polyanion differs from its interaction with DS. The dimeric structure of FXI appears to be required for normal protease function in vivo, and for FXIIa-mediated FXI activation, but not for thrombin- or FXIa-mediated activation in the presence of polyP. Considering that the FXI homolog PK is a monomer that is activated efficiently by FXIIa, and that FXII deficiency is not associated with a significant phenotype, our results suggest that the FXI dimeric structure is required for a function distinct from zymogen activation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Dimer Dissociation and Unfolding Mechanism of Coagulation Factor XI Apple 4 Domain: Spectroscopic and Mutational Analysis

2007 ◽  
Vol 367 (2) ◽  
pp. 558-573 ◽  
Author(s):  
Paul W. Riley ◽  
Hong Cheng ◽  
Dharmaraj Samuel ◽  
Heinrich Roder ◽  
Peter N. Walsh
Keyword(s):  
Mutational Analysis ◽  
Coagulation Factor ◽  
Factor Xi ◽  
Apple 4 Domain

scholarly journals The Second Extracellular Loop of Pore-Forming Subunits of ATP-Binding Cassette Transporters for Basic Amino Acids Plays a Crucial Role in Interaction with the Cognate Solute Binding Protein(s)

2010 ◽  
Vol 192 (8) ◽  
pp. 2150-2159 ◽  
Author(s):  
Viola Eckey ◽  
Daniela Weidlich ◽  
Heidi Landmesser ◽  
Ulf Bergmann ◽  
Erwin Schneider
Keyword(s):  
Amino Acids ◽  
Atpase Activity ◽  
Crucial Role ◽  
Mutational Analysis ◽  
Binding Protein ◽  
Substrate Binding ◽  
Extracellular Loop ◽  
Basic Amino Acids ◽  
Charged Residues ◽  
Positively Charged

ABSTRACT In the thermophile Geobacillus stearothermophilus, the uptake of basic amino acids is mediated by an ABC transporter composed of the substrate binding protein (receptor) ArtJ and a homodimer each of the pore-forming subunit, ArtM, and the nucleotide-binding subunit, ArtP. We recently identified two putative binding sites in ArtJ that might interact with the Art(MP)2 complex, thereby initiating the transport cycle (A. Vahedi-Faridi et al., J. Mol. Biol. 375:448-459, 2008). Here we investigated the contribution of charged amino acid residues in the second extracellular loop of ArtM to contact with ArtJ. Our results demonstrate a crucial role for residues K177, R185, and E188, since mutations to oppositely charged amino acids or glutamine led to a complete loss of ArtJ-stimulated ATPase activity of the complex variants in proteoliposomes. The defects could not be suppressed by ArtJ variants carrying mutations in site I (K39E and K152E) or II (E163K and D170K), suggesting a more complex interplay than that by a single salt bridge. These findings were supported by cross-linking assays demonstrating physical proximity between ArtJ(N166C) and ArtM(E182C). The importance of positively charged residues for receptor-transporter interaction was underscored by mutational analysis of the closely related transporter HisJ/LAO-HisQMP2 of Salmonella enterica serovar Typhimurium. While transporter variants with mutated positively charged residues in HisQ displayed residual ATPase activities, corresponding mutants of HisM could no longer be stimulated by HisJ/LAO. Interestingly, the ATPase activity of the HisQM(K187E)P2 variant was inhibited by l- and d-histidine in detergent, suggesting a role of the residue in preventing free histidine from gaining access to the substrate binding site within HisQM.

Characterization of Recombinant Human Coagulation Factor XFriuli

1996 ◽  
Vol 75 (02) ◽  
pp. 313-317 ◽  
Author(s):  
D J Kim ◽  
A Girolami ◽  
H L James
Keyword(s):  
Catalytic Domain ◽  
Coagulation Factor ◽  
Molecular Size ◽  
Binding Pocket ◽  
Site Directed Mutagenesis ◽  
Bleeding Tendency ◽  
Factor X ◽  
Amino Terminal ◽  
Normal Plasma ◽  
Plasma Factor

SummaryNaturally occurring plasma factor XFriuli (pFXFr) is marginally activated by both the extrinsic and intrinsic coagulation pathways and has impaired catalytic potential. These studies were initiated to obtain confirmation that this molecule is multi-functionally defective due to the substitution of Ser for Pro at position 343 in the catalytic domain. By the Nelson-Long site-directed mutagenesis procedure a construct of cDNA in pRc/CMV was derived for recombinant factor XFriuli (rFXFr) produced in human embryonic (293) kidney cells. The rFXFr was purified and shown to have a molecular size identical to that of normal plasma factor X (pFX) by gel electrophoretic, and amino-terminal sequencing revealed normal processing cleavages. Using recombinant normal plasma factor X (rFXN) as a reference, the post-translational y-carboxy-glutamic acid (Gla) and (β-hydroxy aspartic acid (β-OH-Asp) content of rFXFr was over 85% and close to 100%, respectively, of expected levels. The specific activities of rFXFr in activation and catalytic assays were the same as those of pFXFr. Molecular modeling suggested the involvement of a new H-bond between the side-chains of Ser-343 and Thr-318 as they occur in anti-parallel (3-pleated sheets near the substrate-binding pocket of pFXFr. These results support the conclusion that the observed mutation in pFXFr is responsible for its dysfunctional activation and catalytic potentials, and that it accounts for the moderate bleeding tendency in the homozygous individuals who possess this variant procoagulant.

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