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

Tan CH, Tan KY, Fung SY, Tan NH - BMC Genomics (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia. tanchoohock@gmail.com.

ABSTRACT

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 A2 (PLA2s), 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 PLA2 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.

No MeSH data available.


Related in: MedlinePlus

The Malaysian Ophiophagus hannah venom gland mRNA expression profile. Pie charts mainly display the percentage abundance of toxin transcripts. Toxins transcripts accounted for 35.3 % of the total FPKM. Three-finger toxins are the most abundant toxin family in the venom gland (84.9 % of all toxin transcripts). 3FTx, three-finger toxin; SVMP, snake venom metalloproteinase; PLA2, phospholipase A2; CRISP, cysteine-rich secretory protein; KUN, Kunitz-type proteinase inhibitor; LAAO, L-amino acid oxidase; CVF, Cobra venom factor; IGF, insulin-like growth factor; NP, natriuretic peptide; SVSP, snake venom serine protease; PDE, phosphodiesterase; NGF, nerve growth factor; AChE, acetylcholinesterase; PLB, phospholipase-B; DPP IV, dipeptidylpeptidase IV; CTL, C-type lectin; VEGF, vascular endothelial growth factor
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Fig2: The Malaysian Ophiophagus hannah venom gland mRNA expression profile. Pie charts mainly display the percentage abundance of toxin transcripts. Toxins transcripts accounted for 35.3 % of the total FPKM. Three-finger toxins are the most abundant toxin family in the venom gland (84.9 % of all toxin transcripts). 3FTx, three-finger toxin; SVMP, snake venom metalloproteinase; PLA2, phospholipase A2; CRISP, cysteine-rich secretory protein; KUN, Kunitz-type proteinase inhibitor; LAAO, L-amino acid oxidase; CVF, Cobra venom factor; IGF, insulin-like growth factor; NP, natriuretic peptide; SVSP, snake venom serine protease; PDE, phosphodiesterase; NGF, nerve growth factor; AChE, acetylcholinesterase; PLB, phospholipase-B; DPP IV, dipeptidylpeptidase IV; CTL, C-type lectin; VEGF, vascular endothelial growth factor

Mentions: From the primary output statistics of transcript sequencing, a total of 52,280,572 pairs of clean reads passed the Illumina quality filter for further de novo assembly using the short reads assembling program, Trinity [26]. Trinity created 164,775 Contigs (N50 = 459), connected to form 78,882 Unigenes (N50 = 864) in total as shown in Fig. 1. BLASTx alignment (e-value < 0.00001) between the Unigenes and sequences in the NCBI non-redundant (nr) protein database yielded 36,753 annotated Unigenes (Additional file 1). After filtering low-frequency transcripts (less than 1 FPKM, Fragments Per Kilobase of exon model per Million mapped reads), the assemblies were reduced from 78,882 to 68,472 transcripts and categorized into unidentified (39,888 transcripts), non-toxin (28,456) and toxin (128) groups. Of these, 20 toxin transcripts encode full-length toxin sequences. Although the toxin group accounted for 128 transcripts only, it is abundantly expressed as much as 35.3 % of the total expression (based on the parameter FPKM), whereas the unidentified and non-toxin groups were 20.8 % and 44.9 % respectively (Fig. 2). Toxin transcripts were expressed at extremely higher redundancies (3357.36 FPKM/transcript) compared to non-toxin transcripts (18.81 FPKM/transcript) (Additional file 1).Fig. 1


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

Tan CH, Tan KY, Fung SY, Tan NH - BMC Genomics (2015)

The Malaysian Ophiophagus hannah venom gland mRNA expression profile. Pie charts mainly display the percentage abundance of toxin transcripts. Toxins transcripts accounted for 35.3 % of the total FPKM. Three-finger toxins are the most abundant toxin family in the venom gland (84.9 % of all toxin transcripts). 3FTx, three-finger toxin; SVMP, snake venom metalloproteinase; PLA2, phospholipase A2; CRISP, cysteine-rich secretory protein; KUN, Kunitz-type proteinase inhibitor; LAAO, L-amino acid oxidase; CVF, Cobra venom factor; IGF, insulin-like growth factor; NP, natriuretic peptide; SVSP, snake venom serine protease; PDE, phosphodiesterase; NGF, nerve growth factor; AChE, acetylcholinesterase; PLB, phospholipase-B; DPP IV, dipeptidylpeptidase IV; CTL, C-type lectin; VEGF, vascular endothelial growth factor
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4566206&req=5

Fig2: The Malaysian Ophiophagus hannah venom gland mRNA expression profile. Pie charts mainly display the percentage abundance of toxin transcripts. Toxins transcripts accounted for 35.3 % of the total FPKM. Three-finger toxins are the most abundant toxin family in the venom gland (84.9 % of all toxin transcripts). 3FTx, three-finger toxin; SVMP, snake venom metalloproteinase; PLA2, phospholipase A2; CRISP, cysteine-rich secretory protein; KUN, Kunitz-type proteinase inhibitor; LAAO, L-amino acid oxidase; CVF, Cobra venom factor; IGF, insulin-like growth factor; NP, natriuretic peptide; SVSP, snake venom serine protease; PDE, phosphodiesterase; NGF, nerve growth factor; AChE, acetylcholinesterase; PLB, phospholipase-B; DPP IV, dipeptidylpeptidase IV; CTL, C-type lectin; VEGF, vascular endothelial growth factor
Mentions: From the primary output statistics of transcript sequencing, a total of 52,280,572 pairs of clean reads passed the Illumina quality filter for further de novo assembly using the short reads assembling program, Trinity [26]. Trinity created 164,775 Contigs (N50 = 459), connected to form 78,882 Unigenes (N50 = 864) in total as shown in Fig. 1. BLASTx alignment (e-value < 0.00001) between the Unigenes and sequences in the NCBI non-redundant (nr) protein database yielded 36,753 annotated Unigenes (Additional file 1). After filtering low-frequency transcripts (less than 1 FPKM, Fragments Per Kilobase of exon model per Million mapped reads), the assemblies were reduced from 78,882 to 68,472 transcripts and categorized into unidentified (39,888 transcripts), non-toxin (28,456) and toxin (128) groups. Of these, 20 toxin transcripts encode full-length toxin sequences. Although the toxin group accounted for 128 transcripts only, it is abundantly expressed as much as 35.3 % of the total expression (based on the parameter FPKM), whereas the unidentified and non-toxin groups were 20.8 % and 44.9 % respectively (Fig. 2). Toxin transcripts were expressed at extremely higher redundancies (3357.36 FPKM/transcript) compared to non-toxin transcripts (18.81 FPKM/transcript) (Additional file 1).Fig. 1

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia. tanchoohock@gmail.com.

ABSTRACT

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 A2 (PLA2s), 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 PLA2 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.

No MeSH data available.


Related in: MedlinePlus