Expression and characterization of a fibrinogenolytic enzyme from horsefly salivary gland

•Tablysin 2 is a fibrinogenolytic enzyme from salivary glands of horsefly.•Tablysin 2 was expressed in E. coli with pET-32a (+) plasmid as fusion protein.•Tablysin 2 is anticoagulant by hydrolyzing fibrinogen and inhibiting platelets.•A method for expression of trace proteins in horsefly salivary gland is presented.

Enzymes from various natural resources are valuable in management of thrombosis. Blood-sucking arthropods are one of these resources because they have a wide array of anti-hemostasis molecules in their salivary gland. However, it is difficult to purify enough protein samples from the salivary glands for pharmacological studies. In this work, a fibrinogenolytic enzyme (tablysin 2) identified from salivary glands of the horsefly Tabanus yao was expressed in Escherichia coli to further study its biological activities. The primary structure of tablysin 2 showed significant domain similarity to arthropod proteins from the antigen 5 family containing SCP domain, whose biological functions are poorly understood. Tablysin 2 cleaved the Aα and part of Bβ chains of fibrinogen and did not affect γ chain and fibrin. It inhibited platelet aggregation induced by ADP. It did not directly induce hemorrhage or activate plasminogen. The fibrinogenolytic activity of tablysin 2 provides a clue for the functions of antigen 5-related proteins in other haematophagous arthropods. This work demonstrate a method of expression of arthropod salivary proteins which are difficult to obtain from natural resources for further functional studies.