Molecular cloning, expression, and functional characterizations of novel snake venom metalloproteinases from green pit viper (Trimeresurus albolabris)

Abstract

Molecular cloning and functional characterizations of P-III snake venom metalloproteinases (SVMPs) of the green pit viper (Trimeresurus albolabris) will give us deeper insights in the pathogenesis of viper bites particularly for venom-induced local tissue damages, the complication refractory to current antivenom. The aim of this study was to elucidate the in vitro activities of a new SVMP from the green pit viper (GPV) using recombinant DNA technology. Using the 5-RACE method, a new P-III SVMP cDNA encoding 614 amino acid residue protein, termed “albocollagenase” was obtained. The conceptually translated protein comprised a signal peptide, pro-domain, followed by a metalloproteinase domain containing a zinc-binding motif and 9 cysteine residues, and the disintegrin-like and cysteine-rich domains possessing 24 cysteines and a DCD-motif. The albocollagenase deduced amino acid sequence alignments shown approximately 70 % identity with other P-III SVMPs. Notably, the prodomain was highly conserved, while the metalloproteinase and disintegrin-like and cysteine-rich domains contained several differences. This is the first successful report of the active 62-kDa recombinant P-III SVMP without the signal peptide and prodomain expressed in yeast Pichia pastoris. The recombinant albocollagenase could digest human type IV collagen from human placenta basement membrane within 1 minute, but not human fibrinogen. It also inhibited collagen-induced (but not ADP-induced) platelet aggregation with 50% inhibitory concentration (IC50) of 70 nM. The results suggest the significant roles of P-III SVMP in local and systemic pathology of envenomated patients. Inhibitors of this SVMP may lead to a better treatment for viper bites in the future.