Jerdonuxin, a novel snaclec (snake C-type lectin) with platelet aggregation activity from Trimeresurus jerdonii venom

Serious clinical symptoms of Trimeresurus jerdonii bite are mainly caused by abnormalities of blood system. We have previously identified and characterized several bioactive components affecting human blood system, such as serine proteases, metalloproteinases and disintegrins. But few snaclec was characterized in the T. jerdonii venom. In this study, a novel snaclec, named jerdonuxin, was isolated, molecular cloned and characterized as a human platelet agonist. On SDS-polyacrylamide gel electrophoresis, jerdonuxin showed a single band with an apparent molecular weight of 120 kDa under non-reducing conditions and two distinct bands with apparent molecular weights of 18 kDa (α-subunit) and 14 kDa (β-subunit) under reducing conditions. The cDNA sequence of each subunit of jerdonuxin was identified. The precursors of both subunits contain a 23-amino acid residue signal peptide and the mature proteins are composed of 135 and 125 amino acids for α- and β-subunits, respectively. The N-terminal amino acid sequences of each subunit determined by Edman degradation were consistent with deduced amino acid sequences of cDNA. Jerdonuxin dose-dependently induced human platelet aggregation. The phosphorylation profile pattern induced by jerdonuxin showed similar with mucetin (a platelet agonist via glycoprotein Ib), but different from stejnulxin (an agonist via glycoprotein VI). The jerdonuxin-induced platelet aggregation was inhibited by the anti-GPIbα or anti-GPIIb polyclonal antibodies, but not by anti-GPVI polyclonal antibodies. In summary, a novel snaclec of platelet agonist was purified and characterized from the T. jerdonii venom and our data also suggested that GPIb was involved in jerdonuxin-induced platelet aggregation.