The stratagem utilized by the plasminogen activator from the snake Trimeresurus stejnegeri to escape serpins.
The plasminogen activator isolated from the venom of the snake Trimeresurus stejnegeri (TSV-PA) triggers plasmin production, along with tissue-type plasminogen activators (t-PA) and urokinase (u-PA). The half-life of TSV-PA in plasma is remarkable. We unveil in this paper two of the molecular mechanisms allowing TSV-PA to escape inhibition by plasma serpins. The first involves a phenylalanine at position 193 (chymotrypsinogen numbering system). Phe(193) distinguishes TSV-PA from nearly all trypsin-like proteinases, having glycine at this position. A mutant of TSV-PA (F193G), in which Phe(193) had been replaced by a glycine, was inactivated by plasminogen activator inhibitor 1 (PAI-1) and alpha(2)-antiplasmin 100-fold more rapidly than the wild-type enzyme. The second mechanism originates from the 37-loop of TSV-PA. Swapping the 37-loop of TSV-PA for either that of t-PA or that of u-PA also increased dramatically the rate of inactivation by PAI-1. Loop swapping and F193G mutations were additive, resulting in a rate of inactivation by PAI-1 that was 4 orders of magnitude higher than for the wild-type enzyme. The potential role of Phe(193) and of the 37-loop in the immunity of TSV-PA toward alpha(1)-antitrypsin and antithrombin is also discussed.
Braud
Sandrine
S
Unité des Venins, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France.
Le Bonniec
Bernard F
BF
Bon
Cassian
C
Wisner
Anne
A
D000595:Amino Acid Sequence; D000818:Animals; D000991:Antithrombins / Q000378:metabolism; D001665:Binding Sites; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010960:Plasminogen Activators / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D015843:Serpins / Q000494:pharmacology*; D013917:Thrombin / Q000378:metabolism; D017841:Trimeresurus
D000991:Antithrombins; D011994:Recombinant Proteins; D015843:Serpins; D010960:Plasminogen Activators; D013917:Thrombin