Data from: Venom-gland transcriptome and venom proteome of the Malaysian king cobra (Ophiophagus hannah)

Background: The king cobra (Ophiophagus hannah) is widely distributed
throughout many parts of Asia. This study aims to investigate the
complexity of Malaysian Ophiophagus hannah (MOh) venom for a better
understanding of king cobra venom variation and its envenoming
pathophysiology. The venom gland transcriptome was investigated using the
Illumina HiSeq™ platform, while the venom proteome was profiled by
1D-SDS-PAGE-nano-ESI-LCMS/MS. Results: Transcriptomic results reveal high
redundancy of toxin transcripts (3357.36 FPKM/transcript) despite small
cluster numbers, implying gene duplication and diversification within
restricted protein families. Among the 23 toxin families identified,
three-finger toxins (3FTxs) and snake-venom metalloproteases (SVMPs) have
the most diverse isoforms. These 2 toxin families are also the most
abundantly transcribed, followed in descending order by phospholipases A 2
(PLA 2 s), cysteine-rich secretory proteins (CRISPs), Kunitz-type
inhibitors (KUNs), and L-amino acid oxidases (LAAOs). Seventeen toxin
families exhibited low mRNA expression, including hyaluronidase, DPP-IV
and 5’-nucleotidase that were not previously reported in the venom-gland
transcriptome of a Balinese O. hannah. On the other hand, the MOh proteome
includes 3FTxs, the most abundantly expressed proteins in the venom (43 %
toxin sbundance). Within this toxin family, there are 6 long-chain, 5
short-chain and 2 non-conventional 3FTx. Neurotoxins comprise the major
3FTxs in the MOh venom, consistent with rapid neuromuscular paralysis
reported in systemic envenoming. The presence of toxic enzymes such as
LAAOs, SVMPs and PLA 2 would explain tissue inflammation and necrotising
destruction in local envenoming. Dissimilarities in the subtypes and
sequences between the neurotoxins of MOh and Naja kaouthia (monocled
cobra) are in agreement with the poor cross-neutralization activity of N.
kaouthia antivenom used against MOh venom. Besides, the presence of cobra
venom factor, nerve growth factors, phosphodiesterase, 5’-nucleotidase,
and DPP-IV in the venom proteome suggests its probable hypotensive action
in subduing prey. Conclusion: This study reports the diversity and
abundance of toxins in the venom of the Malaysian king cobra (MOh). The
results correlate with the pathophysiological actions of MOh venom, and
dispute the use of Naja cobra antivenoms to treat MOh envenomation. The
findings also provide a deeper insight into venom variations due to
geography, which is crucial for the development of a useful pan-regional
antivenom.