Novel anticoagulant proteins identified in the salivary glands of Rhipicephalus sanguineus and their interaction with coagulation factor X.

In the salivary glands of the hematophagous arthropod R. sanguineus, a total of 122 protein coding sequences interacting with coagulation factor X (FX) were identified using the yeast two-hybrid (Y2H) technology, including 100 characterized proteins, and 22 uncharacterized. Three proteins, ferritin-like, tyrosine-protein phosphatase Lar-like, and elongation factor 1 alpha, were selected for cloning, demonstrated significant impacts on four key coagulation parameters: prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and fibrinogen (FIB) levels. They significantly prolonged PT, APTT, and TT, and reduced FIB levels, indicating interactions with both extrinsic and endogenous coagulation pathways and potential interference with fibrinogen synthesis, metabolism, or functional activity. Docking simulations between the proteins and FX provided evidence of stable, specific protein-protein complexes, mediated by hydrophobic forces. The high confidence scores and diverse interaction modes suggested evolutionary refinement for tight, specific binding to FX. The study introduced promising anticoagulant molecules from hematophagous arthropods, rigorously validated their activity, and highlighted their potential for research and therapeutic applications. These findings have implications for the development of new anticoagulant and antithrombotic therapeutics, underscoring the importance of exploring natural sources for new drugs to expand the drug pipeline in cardiovascular medicine.