The venom gland transcriptome of the Desert Massasauga Rattlesnake (Sistrurus catenatus edwardsii): towards an understanding of venom composition among advanced snakes (Superfamily Colubroidea)

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Abstract

Background

Snake venoms are complex mixtures of pharmacologically active proteins and peptides which belong to a small number of superfamilies. Global cataloguing of the venom transcriptome facilitates the identification of new families of toxins as well as helps in understanding the evolution of venom proteomes.

Results

We have constructed a cDNA library of the venom gland of a threatened rattlesnake (a pitviper), Sistrurus catenatus edwardsii (Desert Massasauga), and sequenced 576 ESTs. Our results demonstrate a high abundance of serine proteinase and metalloproteinase transcripts, indicating that the disruption of hemostasis is a principle mechanism of action of the venom. In addition to the transcripts encoding common venom proteins, we detected two varieties of low abundance unique transcripts in the library; these encode for three-finger toxins and a novel toxin possibly generated from the fusion of two genes. We also observed polyadenylated ribosomal RNAs in the venom gland library, an interesting preliminary obsevation of this unusual phenomenon in a reptilian system.

Conclusion

The three-finger toxins are characteristic of most elapid venoms but are rare in viperid venoms. We detected several ESTs encoding this group of toxins in this study. We also observed the presence of a transcript encoding a fused protein of two well-characterized toxins (Kunitz/BPTI and Waprins), and this is the first report of this kind of fusion in a snake toxin transcriptome. We propose that these new venom proteins may have ancillary functions for envenomation. The presence of a fused toxin indicates that in addition to gene duplication and accelerated evolution, exon shuffling or transcriptional splicing may also contribute to generating the diversity of toxins and toxin isoforms observed among snake venoms. The detection of low abundance toxins, as observed in this and other studies, indicates a greater compositional similarity of venoms (though potency will differ) among advanced snakes than has been previously recognized.

Related collections

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Author and article information

Journal

Journal ID (nlm-ta): BMC Mol Biol

Title: BMC Molecular Biology

Publisher: BioMed Central

ISSN (Electronic): 1471-2199

Publication date Collection: 2007

Publication date (Electronic): 20 December 2007

Volume: 8

Page: 115

Affiliations

[1 ]Center for Post Graduate Studies, Sri Bhagawan Mahaveer Jain College, 18/3, 9th Main, Jayanagar 3rd Block, Bangalore, India

[2 ]School of Biological Sciences, University of Northern Colorado, Greeley, CO 80639-0017, USA

[3 ]Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, Singapore 117543 and Deparment of Biochemistry, Virginia Commonwealth University, Medical college of Virginia, Richmond, VA 23298-0614, USA

Article

Publisher ID: 1471-2199-8-115

DOI: 10.1186/1471-2199-8-115

PMC ID: 2242803

PubMed ID: 18096037

SO-VID: 69c48c42-d7f3-4a48-ba89-3f42bd7dc1aa

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.