Colubrid Venom Composition: An -Omics Perspective.

Inácio L M Junqueira-De-Azevedo,Ana T C Ching,Stephen P Mackessy,Pollyanna F Campos

doi:10.3390/toxins8080230

Inácio L M Junqueira-De-Azevedo, Ana T C Ching + Show 2 more

Open Access

https://doi.org/10.3390/toxins8080230

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Journal: Toxins	Publication Date: Jul 23, 2016
Citations: 66	License type: CC BY 4.0

Affiliation: Instituto Butantan, University of Northern Colorado

Abstract

Snake venoms have been subjected to increasingly sensitive analyses for well over 100 years, but most research has been restricted to front-fanged snakes, which actually represent a relatively small proportion of extant species of advanced snakes. Because rear-fanged snakes are a diverse and distinct radiation of the advanced snakes, understanding venom composition among “colubrids” is critical to understanding the evolution of venom among snakes. Here we review the state of knowledge concerning rear-fanged snake venom composition, emphasizing those toxins for which protein or transcript sequences are available. We have also added new transcriptome-based data on venoms of three species of rear-fanged snakes. Based on this compilation, it is apparent that several components, including cysteine-rich secretory proteins (CRiSPs), C-type lectins (CTLs), CTLs-like proteins and snake venom metalloproteinases (SVMPs), are broadly distributed among “colubrid” venoms, while others, notably three-finger toxins (3FTxs), appear nearly restricted to the Colubridae (sensu stricto). Some putative new toxins, such as snake venom matrix metalloproteinases, are in fact present in several colubrid venoms, while others are only transcribed, at lower levels. This work provides insights into the evolution of these toxin classes, but because only a small number of species have been explored, generalizations are still rather limited. It is likely that new venom protein families await discovery, particularly among those species with highly specialized diets.

Highlights

More than one hundred years of biochemical and pharmacological studies have resulted in an exceptional depth of knowledge about snake venoms
Our attempt to compile the toxins present in colubrids was based on three strategies: (1) generating transcriptomic sequences from the venom glands of three species of colubrids, Erythrolamprus miliaris, Oxyrhopus guibei and Xenodon merremi (Dipsadinae subfamily of Colubridae), to identify transcripts coding for known and putative types of snake toxins (Table S1); (2) prospecting public databases for toxin-related sequences in other colubrid species previously investigated; and (3) reviewing the literature on colubrid venoms that describes the isolation of toxins or provides clear evidence for the occurrence of specific proteins in colubrid venoms
The protein types compiled were organized into three categories: (a) “major snake venom components” (Table 1), referring to protein types generally encountered in high amounts in the venoms of many species of traditionally venomous snakes (Viperidae, Elapidae and Atractaspididae) and which certainly are important toxins; (b) “minor venom components” (Table 2), referring to protein types previously described in the venom of some species of venomous snakes, generally in low amounts, and which may represent toxins, ancillary venom proteins or housekeeping proteins; and (c) “putative new snake toxins in colubrid venoms” (Table 3), referring to protein types uncovered from colubrid venom analyses, occurring in high or low quantities, which may represent putative toxins, exclusive or not to the group

Summary

Introduction

More than one hundred years of biochemical and pharmacological studies have resulted in an exceptional depth of knowledge about snake venoms. The major toxins of the most medically important taxa of venomous snakes were determined by first generation approaches including protein chemistry, comparative pharmacology and cladistics methods borrowed from evolutionary biology. (cf [1,2,3]), have further accelerated the pace of sequence acquisition and compositional analysis and constituted the basis of large-scale biotechnological explorative initiatives (e.g., [4]). These studies collectively created very complete inventories of the toxin families and superfamilies present in Toxins 2016, 8, 230; doi:10.3390/toxins8080230 www.mdpi.com/journal/toxins. The association of quantified toxins with empirically demonstrated activities have allowed predictions of functional and ecological roles for the species that produce these toxins (e.g., [19,20,21,22])

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