Original Publication Date
BMC Molecular Biology
DOI of Original Publication
Date of Submission
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 inBungarus 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. flavicepsvenom, which may help in understanding the evolution of venom toxins and the pathophysiological symptoms induced after envenomation.
© 2010 Siang et al; licensee BioMed Central Ltd. 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.
Is Part Of
VCU Biochemistry and Molecular Biology Publications
Transcripts submitted to database showing similarity to snake venom protein family. Numbers of transcripts, accession number, search programme and E values are shown in the table.
1471-2199-11-24-s2.pdf (33 kB)
% of venom proteins families observed in venom gland transcriptome. Comparison of different toxin families observed in transcriptome of elapid and viperid venom gland.
1471-2199-11-24-s3.pdf (9 kB)
ASSET in 3FTxs of B. flaviceps. Alignment of 3FTx of B. flaviceps showing Accelerated Segment Switch in Exon to alter Targeting (ASSET). The segments which are similar are shown in same color where as segments which are dissimilar are shown in different color. The clone name and the number of clones are also shown in the figure.
1471-2199-11-24-s4.pdf (13 kB)
Premature truncated kunitz type SPI from B. flaviceps. Comparison of protein and nucleotide of truncated kunitz type SPI from B. flaviceps with EU246693 from Ophiophagus hannah. Exons are highlighted with different colors, Exon I is highlighted with red color, Exon II with Blue and Exon III is in grey color. 87 Nucleotides are deleted from the exon II of BF539 as shown with dashes in the figure. Comparison of the mRNA sequence of BF539 with BF294 reveals that a dinucleotide "GT" (underlined and highlighted in red letter) is present at the end of the exon II of BF539. The splicing error could be due to change in this base substitution. However the exon III is intact as stop codon and one of the amino acid residue is encoded by the exon III
1471-2199-11-24-s5.pdf (14 kB)
Phylogenetic relationship of B chain and Kunitz SPI of different Bungarus species. Kunitz type SPI and B chain of β-bungarotoxin of Bungarus sp was obtained from the database and phylogenetic tree was constructed to understand the relationship between kunitz SPI and B chain of β-bungarotoxin.
1471-2199-11-24-s6.pdf (13 kB)
Comparison of BF95 from B. flaviceps with Laticauda semifasciata PLA2(AB062439). Exons are highlighted with different colors, Exon I is highlighted in green color; Exon II in magenta; Exon III in dark blue and Exon IV in grey. In BF95, part of the exon II (99 bp) is missing as shown in the figure with dashes.
1471-2199-11-24-s7.pdf (11 kB)
CRISPs and C-type lectins. A) Transcripts encoding CRISPs (BF53), found in this venom gland cDNA library. B) C-type lectins (BF53) found in this venom gland cDNA library. One of the C-type lectin found in this venom gland cDNA library was truncated in the 5' end (BF764). The amino acid residues of C-type lectin involved in binding to the Ca2+ are highlighted with green color and the cysteine residues are highlighted.