Evaluation of Antiplatelet Effects of Type C Lectin From Bothrops neuwiedi Venom

Lectins are non-enzymatic proteins that bind reversibly and specifically to carbohydrates. In snake venoms, lectins are grouped into classical lectins, which bind Ca2+ and sugars (CTLs), and non-sugar-binding snake venom C-type lectin-related proteins (CLRPs). These proteins target distinct molecules, such as coagulation factors and receptors, on platelet surfaces and endothelial or immune cells, which are involved in hemostasis, inflammation and metastasis. Because of their specificity and versatility, C-type lectins are used as models in biotechnological studies and applications. Toward this goal, the current study aims to determine the molecular and biochemical properties of the C-type lectin isolated from Bothrops neuwiedi venom (CTL-Bn). The protein was isolated by D-galactose column affinity chromatography and analyzed by SDS-PAGE and mass spectrometry. We demonstrate that CTL-Bn forms oligomers whose monomers have a molecular mass of approximately 15 kDa. CTL-Bn induced hemagglutination at a minimum dose of 2.5 μg, which was inhibited by galactose, lactose and EDTA. The protein is stable at a wide pH range and shows optimal activity at 20 °C. Furthemore, CTL-Bn inhibits platelet aggregation induced by convulxin and binds to fibrinogen and glycoprotein GPVI (the main collagen receptor), which probably explains its inhibitory effect on convulxin-induced platelet aggregation. Based on docking molecular studies, we proposed that CTL-Bn binds to GPVI in a region formed by hydrophobic residues with polar and basic residues around the periphery. To evaluate the role of CTL-Bn in the metastatic process, we tested CTL-Bn on platelet aggregation induced by MDA-MB-231 tumor cells. CTL-Bn inhibited this aggregation; however, in the MTT assay, the protein did not affect the viability of the tumor cells. Altogether, our results provided a comprehensive biochemical, biological and structural characterization of CTL-Bn.