Venomics of the Central American Lyre Snake Trimorphodon quadruplex (Colubridae: Smith, 1941) from Costa Rica

Abstract

Rear-fanged colubrid snakes include hundreds of species globally that possess a Duvernoy's venom gland and often one-several enlarged rear maxillary teeth. We investigated the venom proteome of the Central American Lyre Snake (Trimorphodon quadruplex), a moderate-sized rear-fanged colubrid snake and the southernmost Trimorphodon, using a bottom-up proteomic approach coupled with enzyme and inhibitor assays, cytotoxicity assays and lethal toxicity assays. Several enzymes uncommonly observed in colubrid venoms were purified and characterized further. Trimorphodon quadruplex has a rather low complexity venome, typical of many rear-fanged snakes, but its venom contains L-amino acid oxidase, phospholipase A2, and a dimeric 3FTx, and 3FTxs dominate the proteome. Its PLA2 is catalytically quite active, but it lacks myotoxicity or acute toxicity; LAAO exhibits conserved structure and appears to be highly labile. Several P-III metalloproteinases are present and hydrolyze azocasein and the α-subunit of fibrinogen but lack hemorrhagic activity. Trimorphodon quadruplex produces venom and retains constriction, utilizing both chemically-mediated and mechanical feeding modes. SignificanceWe demonstrate that T. quadruplex venom proteins are similar to those found in front-fanged snake species are present but show different biological activities. Our results underscore the importance of considering the biological roles of venoms from more than a mammal-centric perspective.