Article (Scientific journals)
Basic residues of human group IIA phospholipase A2 are important for binding to factor Xa and prothrombinase inhibition comparison with other mammalian secreted phospholipases A2.
Mounier, C. M.; Luchetta, P.; Lecut, Christelle et al.
2000In European Journal of Biochemistry, 267 (16), p. 4960-9
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Keywords :
Amino Acid Sequence; Amino Acid Substitution; Animals; Base Sequence; Bothrops; Factor Xa/metabolism; Group II Phospholipases A2; Humans; Mammals; Mice; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Phospholipases A/chemistry/metabolism; Phospholipases A2; Phospholipids/metabolism; Protein Conformation; Rats; Recombinant Proteins/chemistry/metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Surface Plasmon Resonance; Thrombin/metabolism; Thromboplastin/antagonists & inhibitors
Abstract :
[en] Human secreted group IIA phospholipase A2 (hGIIA) was reported to inhibit prothrombinase activity because of binding to factor Xa. This study further shows that hGIIA and its catalytically inactive H48Q mutant prolong the lag time of thrombin generation in human platelet-rich plasma with similar efficiency, indicating that hGIIA exerts an anticoagulant effect independently of phospholipid hydrolysis under ex vivo conditions. Charge reversal of basic residues on the interfacial binding surface (IBS) of hGIIA leads to decreased ability to inhibit prothrombinase activity, which correlates with a reduced affinity for factor Xa, as determined by surface plasmon resonance. Mutation of other surface-exposed basic residues, hydrophobic residues on the IBS, and His48, does not affect the ability of hGIIA to inhibit prothrombinase activity and bind to factor Xa. Other basic, but not neutral or acidic, mammalian secreted phospholipases A2 (sPLA2s) exert a phospholipid-independent inhibitory effect on prothrombinase activity, suggesting that these basic sPLA2s also bind to factor Xa. In conclusion, this study demonstrates that the anticoagulant effect of hGIIA is independent of phospholipid hydrolysis and is based on its interaction with factor Xa, leading to prothrombinase inhibition, even under ex vivo conditions. This study also shows that such an interaction involves basic residues located on the IBS of hGIIA, and suggests that other basic mammalian sPLA2s may also inhibit blood coagulation by a similar mechanism to that described for hGIIA.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Mounier, C. M.
Luchetta, P.
Lecut, Christelle ;  Institut Pasteur (Paris, France) > Unité des Venins
Koduri, R. S.
Faure, G.
Lambeau, G.
Valentin, E.
Singer, A.
Ghomashchi, F.
Beguin, S.
Gelb, M. H.
Bon, C.
Language :
English
Title :
Basic residues of human group IIA phospholipase A2 are important for binding to factor Xa and prothrombinase inhibition comparison with other mammalian secreted phospholipases A2.
Publication date :
2000
Journal title :
European Journal of Biochemistry
ISSN :
0014-2956
eISSN :
1432-1033
Publisher :
Blackwell Science, Oxford, United Kingdom
Volume :
267
Issue :
16
Pages :
4960-9
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 28 August 2009

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