Serpin–Glycosaminoglycan Interactions

Rein, Chantelle M.; Desai, Umesh R.; Church, Frank C.

doi:10.1016/b978-0-12-385950-1.00007-9

Cited by 41 publications

(32 citation statements)

References 105 publications

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“…A high SI index could also be explained by the possibility that AAS19 requires a co-factor to enhance inhibition. Indeed, nearly all serpin acting upon the blood clotting activation cascade and fibrinolysis (antithrombin III, heparin-cofactor II, plasminogen activator inhibitor 1, protein C inhibitor and protease nexin inhibitor) need to bind GAGs in order to accelerate the inhibition rate, which can be up to 10,000-fold higher compared with the unbound native serpin (Rein et al, 2011). Accordingly, Z-protein-dependent inhibitor (ZPI) has been shown to accelerate the inhibitory effect of ZPI upon fXa by 1000-fold (Broze, Jr., 2001; Munoz and Linhardt, 2004).…”

Section: Discussionmentioning

confidence: 99%

Conserved Amblyomma americanum tick Serpin19, an inhibitor of blood clotting factors Xa and XIa, trypsin and plasmin, has anti-haemostatic functions

Kim

Tirloni

Radulović

et al. 2015

International Journal for Parasitology

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Tick saliva serine protease inhibitors (serpins) facilitate tick blood meal feeding through inhibition of protease mediators of host defense pathways. We previously identified a highly conserved Amblyomma americanum serpin (AAS) 19 that is characterized by its reactive center loop being 100% conserved in ixodid ticks. In this study, biochemical characterization reveals that the ubiquitously transcribed AAS19 is an anti-coagulant protein, inhibiting the activity of five of the eight serine protease blood clotting factors. Pichia pastoris-expressed recombinant (r) AAS19 inhibits the enzyme activity of trypsin, plasmin and blood clotting factors (f) Xa and XIa, with stoichiometry of inhibition estimated at 5.1, 9.4, 23.8 and 28, respectively. Similar to typical inhibitory serpins, rAAS19 forms irreversible complexes with trypsin, fXa and fXIa. At a higher molar excess of rAAS19, fXIIa is inhibited by 82.5%, and thrombin (fIIa), fIXa, chymotrypsin and tryptase are inhibited moderately by 14 – 29%. In anti-hemostatic functional assays, rAAS19 inhibits thrombin but not ADP and cathepsin G activated platelet aggregation, delays clotting in recalcification and thrombin time assays by up to 250 s, and up to 40 s in the activated partial thromboplastin time assay. Given AAS19 high cross-tick species conservation, and specific reactivity of rAAS19 with antibodies to A. americanum tick saliva proteins, we conclude that rAAS19 is a potential candidate for development of a universal tick vaccine.

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Section: Discussionmentioning

confidence: 99%

Conserved Amblyomma americanum tick Serpin19, an inhibitor of blood clotting factors Xa and XIa, trypsin and plasmin, has anti-haemostatic functions

Kim

Tirloni

Radulović

et al. 2015

International Journal for Parasitology

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“…HS and heparin enhance the anticoagulant activity of plasma serpins by binding to HCII, ATIII and protein C inhibitor [13,18,19]. However, HS, but not heparin, degraded serpin molecules as shown in Fig.…”

Section: Discussionmentioning

confidence: 89%

Heparin cofactor II is degraded by heparan sulfate and dextran sulfate

Saito

2015

Biochemical and Biophysical Research Communications

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“…Important serpin regulators of the mammalian blood clotting system, antithrombin III , protein C inhibitor, and heparin cofactor II need to bind glycosaminoglycans (GAGs) to achieve physiologically relevant rates of activity (Berliner, 2012; Pratt and Church, 1992; Rein et al, 2011; Tollefsen, 1997). In other serpins such as the α1-antitrypsin and plasminogen activator inhibitor 1, GAG binding inhibits their inhibitory functions (Carrell, 2016; Ehrlich et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Heparan sulfate/heparin glycosaminoglycan binding alters inhibitory profile and enhances anticoagulant function of conserved Amblyomma americanum tick saliva serpin 19

Radulović

Mulenga

2017

Insect Biochemistry and Molecular Biology

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Some serine protease inhibitor (serpin) regulators of essential life pathways bind glycosaminoglycans (GAGs) to enhance inhibitory functions and achieve physiologically relevant rates. This study demonstrates that highly conserved Amblyomma americanum tick saliva serpin 19 (AAS19), a broad-spectrum inhibitor of hemostasis and inflammation system proteases and anticoagulant, can bind heparan sulfate/heparin (HS)GAGs and that this interaction alters its function. Substrate hydrolysis and unpaired t-test analyses revealed that HSGAG binding caused rAAS19 inhibitory activity to: (i) significantly increase against blood clotting factors (f) IIa (thrombin) and fIXa, (ii) significantly reduce against fXa and fXIIa and (iii) moderate to no effect against trypsin, kallikrein, papain, and plasmin. Stoichiometry of inhibition (SI) analyses show that HSGAG binding improved the rAAS19 inhibitory efficiency against thrombin 2.7-4.3 folds as revealed by SI of 13.19 in absence of HSGAGs to 4.83-3.04 in their presence. Our data show that HSGAG binding dramatically enhanced rAAS19 anticoagulant function. In the recalcification time assay, rAAS19 pre-incubated with HSGAGs prior to the assay, delayed plasma clotting by an additional 176-457 s above HSGAGs or rAAS19 alone. Our data suggest that formation of the HSGAGs and rAAS19 complex is important for the observed enhanced anticoagulant effect. Delay of plasma clotting was higher when HSGAGs and rAAS19 were co-incubated to allow complex formation prior to blood clotting assay as opposed to no co-incubation. We have discussed our finding with reference to tick feeding physiology and utility of the rAAS19 in blood clotting disorder therapy.

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Serpin–Glycosaminoglycan Interactions

Cited by 41 publications

References 105 publications

Conserved Amblyomma americanum tick Serpin19, an inhibitor of blood clotting factors Xa and XIa, trypsin and plasmin, has anti-haemostatic functions

Conserved Amblyomma americanum tick Serpin19, an inhibitor of blood clotting factors Xa and XIa, trypsin and plasmin, has anti-haemostatic functions

Heparin cofactor II is degraded by heparan sulfate and dextran sulfate

Heparan sulfate/heparin glycosaminoglycan binding alters inhibitory profile and enhances anticoagulant function of conserved Amblyomma americanum tick saliva serpin 19

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