Cleavage of factor XIII by human neutrophil elastase results in a novel active truncated form of factor XIII A subunit

• Published in: Thrombosis and haemostasis Vol. 99; no. 4; p. 668
• Main Authors: Bagoly, Zsuzsa, Fazakas, Ferenc, Komáromi, István, Haramura, Gizella, Tóth, Eszter, Muszbek, Lászlo
• Format: Journal Article
• Language: English
• Published: Germany 01.04.2008
• Subjects: Amino Acid Sequence; Binding Sites - genetics; Blotting, Western; Cross-Linking Reagents; Factor XIII - chemistry; Factor XIII - genetics; Factor XIII - metabolism; Factor XIIIa - chemistry; Factor XIIIa - genetics; Factor XIIIa - metabolism; Fibrin - chemistry; Fibrin - metabolism; Humans; In Vitro Techniques; Kinetics; Leukocyte Elastase - metabolism; Models, Molecular; Molecular Sequence Data; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; Protein Conformation; Protein Subunits
• ISSN: 0340-6245
• DOI: 10.1160/TH07-09-0577

The first step in the activation of plasma factor XIII (FXIII) is the cleavage of R37-G38 bond in FXIII-A subunit (FXIII-A) by thrombin, which makes the subsequent formation of an active transglutaminase possible. No active truncated form of FXIII-A, other than G38-FXIII-A, has been identified. In contrast to thrombin, which has a preference toward arginine residues, human neutrophil elastase (HNE) cleaves peptide bonds at small side-chain aliphatic amino acids, preferably at valine. As there are several valine residues close to the thrombin cleavage-site, we tested if an active truncated FXIII-A was formed during fragmentation of FXIII by HNE. It was demonstrated by Western blotting and transglutaminase assay that HNE induced a limited cleavage of FXIII-A resulting in the activation of both plasma and cellular FXIII; the maximal transglutaminase activities were 52.5% and 67.4% of thrombin-activated FXIII, respectively. After the relatively rapid activation a much slower inactivation occurred. HNE-activated FXIII cross-linked fibrin gamma- and alpha-chains in the clot formed by batroxobin moojeni. MALDI-TOF analysis of the cleaved fragments and N-terminal Edman degradation of the truncated protein identified V39-N40 as the primary cleavage-site and N40-FXIII-A as the active form. No primary cleavage occurred at V34, V35, V47, V50 residues. FXIII-A V34L polymorphism, which increases the rate of FXIII-A cleavage by thrombin, was without effect on FXIII activation by HNE. Molecular modeling located the primary HNE cleavage-site in the middle of the flexible and accessible Q32-L45 loop and showed that other neighboring valine residues were in less favorable position.