Unusual accelerated rate of deletions and insertions in toxin genes in the venom glands of the pygmy copperhead (Austrelaps labialis) from kangaroo island

doi:10.1186/1471-2148-8-70

BMC Evolutionary Biology

Volume 8

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Research article

Unusual accelerated rate of deletions and insertions in toxin genes in the venom glands of the pygmy copperhead (Austrelaps labialis) from kangaroo island

Robin Doley¹^* , Nguyen Ngoc Bao Tram¹^* , Md Abu Reza¹ and R Manjunatha Kini¹^,2

¹Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore

²Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Block S3, # 03-17, 117543, Singapore

author email corresponding author email* Contributed equally

BMC Evolutionary Biology 2008, 8:70doi:10.1186/1471-2148-8-70


Published:	28 February 2008

Abstract

Background

Toxin profiling helps in cataloguing the toxin present in the venom as well as in searching for novel toxins. The former helps in understanding potential pharmacological profile of the venom and evolution of toxins, while the latter contributes to understanding of novel mechanisms of toxicity and provide new research tools or prototypes of therapeutic agents.

Results

The pygmy copperhead (Austrelaps labialis) is one of the less studied species. In this present study, an attempt has been made to describe the toxin profile of A. labialis from Kangaroo Island using the cDNA library of its venom glands. We sequenced 658 clones which represent the common families of toxin genes present in snake venom. They include (a) putative long-chain and short-chain neurotoxins, (b) phospholipase A₂, (c) Kunitz-type protease inhibitor, (d) CRISPs, (e) C-type lectins and (f) Metalloproteases. In addition, we have also identified a novel protein with two Kunitz-type domains in tandem similar to bikunin.

Conclusion

Interestingly, the cDNA library reveals that most of the toxin families (17 out of 43 toxin genes; ~40%) have truncated transcripts due to insertion or deletion of nucleotides. These truncated products might not be functionally active proteins. However, cellular trancripts from the same venom glands are not affected. This unusual higher rate of deletion and insertion of nucleotide in toxin genes may be responsible for the lower toxicity of A. labialis venom of Kangroo Island and have significant effect on evolution of toxin genes.