Transcriptomic analysis of the venom gland of the red-headed krait (Bungarus flaviceps) using expressed sequence tags
1 Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117546, Singapore
2 Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur-784 028, Assam, India
3 Institute of Biology, Leiden University, Sylvius Laboratory, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
4 Department of Biochemistry and Molecular Biology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298-0614, USA
BMC Molecular Biology 2010, 11:24 doi:10.1186/1471-2199-11-24Published: 29 March 2010
The Red-headed krait (Bungarus flaviceps, Squamata: Serpentes: Elapidae) is a medically important venomous snake that inhabits South-East Asia. Although the venoms of most species of the snake genus Bungarus have been well characterized, a detailed compositional analysis of B. flaviceps is currently lacking.
Here, we have sequenced 845 expressed sequence tags (ESTs) from the venom gland of a B. flaviceps. Of the transcripts, 74.8% were putative toxins; 20.6% were cellular; and 4.6% were unknown. The main venom protein families identified were three-finger toxins (3FTxs), Kunitz-type serine protease inhibitors (including chain B of β-bungarotoxin), phospholipase A2 (including chain A of β-bungarotoxin), natriuretic peptide (NP), CRISPs, and C-type lectin.
The 3FTxs were found to be the major component of the venom (39%). We found eight groups of unique 3FTxs and most of them were different from the well-characterized 3FTxs. We found three groups of Kunitz-type serine protease inhibitors (SPIs); one group was comparable to the classical SPIs and the other two groups to chain B of β-bungarotoxins (with or without the extra cysteine) based on sequence identity. The latter group may be functional equivalents of dendrotoxins in Bungarus venoms. The natriuretic peptide (NP) found is the first NP for any Asian elapid, and distantly related to Australian elapid NPs. Our study identifies several unique toxins in B. flaviceps venom, which may help in understanding the evolution of venom toxins and the pathophysiological symptoms induced after envenomation.