Transcriptomic analysis of the venom gland of the red-headed krait (Bungarus flaviceps) using expressed sequence tags

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.Snake venom is a complex mixture of biologically active proteins and peptides that exert very powerful and specific effects. This mixture is interesting from the angle of molecular evolution, as the genes encoding the venom ingredients seem to undergo some form of hypermutation resulting in accelerated evolution and a staggering diversity of isoforms [1,2], sometimes functionally and structurally radically different. The basis for this phenomenon seems to be due to gene-duplication and diversification of existing venom genes. This results in a highly dynamic venom composition both at the interspecific and intraspecific level [3]. This allows the snake to deal with a wide array of different prey items. Snake venom is also a valuabl