Parallel prothrombin activator systems in Australian Elapids: Their structure, gene organization, evolution and regulation of expression

Abstract

Australian elapid venom contains prothrombin activators which are structurally and functionally similar to blood coagulation factors such as factor Xa and factor Va. Thus, these snakes have two parallel prothrombin activating systems; one in plasma which plays crucial role in hemostasis, whereas the other in venom acts as toxin. Present study describes the structure, genomic organization and regulation of expression of the venom prothrombin activators (trocarin D in Tropidechis carinatus/pseutarin C in Pseudonaja textilis) and their plasma counterparts. Both prothrombin activators have similar gene organization with high sequence identity. The unique insertion and deletion pattern in their promoter and intron 1 sequences and the existence of an intermediate FX transcript in P. textiles liver indicates that the venom prothrombin activator originated by gene duplication of FX gene and subsequently marked for tissue specific expression in the venom gland. These studies will contribute towards the understanding of the recruitment, evolution and the regulation of snake venom prothrombin activators.