New Infestin-4 Mutants with Increased Selectivity against Factor XIIa

• Published in: PloS one 2015-12, Vol.10 (12), p.e0144940-e0144940
• Main Authors: Kolyadko, Vladimir N, Lushchekina, Sofya V, Vuimo, Tatiana A, Surov, Stepan S, Ovsepyan, Ruzanna A, Korneeva, Vera A, Vorobiev, Ivan I, Orlova, Nadezhda A, Minakhin, Leonid, Kuznedelov, Konstantin, Severinov, Konstantin V, Ataullakhanov, Fazoil I, Panteleev, Mikhail A
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Assaying; Bioengineering; Bioinformatics; Blood clots; Blood Coagulation - drug effects; Clotting; Coagulation; Docking; Drug Design; Factor Xa - metabolism; Factor XIIa - antagonists & inhibitors; Factor XIIa - metabolism; Gene mutation; Health physics; Hematology; Humans; Immunology; Insect Proteins - chemistry; Insect Proteins - genetics; Insect Proteins - pharmacology; Kinetics; Molecular dynamics; Molecular Sequence Data; Mutant Proteins - pharmacology; Mutants; Mutation; Oncology; Pediatrics; Pharmacology; Physics; Plant Proteins - pharmacology; Plasma; Plasmin; Protease; Protease Inhibitors - pharmacology; Protein Binding - drug effects; Proteins; Reagents; Selectivity; Serine; Serine proteinase; Substrate Specificity; Thioredoxins - metabolism; Thrombin; Thromboembolism; Thrombosis; Tissue factor
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0144940

Factor XIIa (fXIIa) is a serine protease that triggers the coagulation contact pathway and plays a role in thrombosis. Because it interferes with coagulation testing, the need to inhibit fXIIa exists in many cases. Infestin-4 (Inf4) is a Kazal-type inhibitor of fXIIa. Its specificity for fXIIa can be enhanced by point mutations in the protease-binding loop. We attempted to adapt Inf4 for the selective repression of the contact pathway under various in vitro conditions, e.g., during blood collection and in 'global' assays of tissue factor (TF)-dependent coagulation. First, we designed a set of new Inf4 mutants that, in contrast to wt-Inf4, had stabilized canonical conformations during molecular dynamics simulation. Off-target activities against factor Xa (fXa), plasmin, and other coagulation proteases were either reduced or eliminated in these recombinant mutants, as demonstrated by chromogenic assays. Interactions with fXIIa and fXa were also analyzed using protein-protein docking. Next, Mutant B, one of the most potent mutants (its Ki for fXIIa is 0.7 nM) was tested in plasma. At concentrations 5-20 μM, this mutant delayed the contact-activated generation of thrombin, as well as clotting in thromboelastography and thrombodynamics assays. In these assays, Mutant B did not affect coagulation initiated by TF, thus demonstrating sufficient selectivity and its potential practical significance as a reagent for coagulation diagnostics.