De novo venom gland transcriptomics of Calliophis bivirgata flaviceps: Uncovering the complexity of toxins from the Malayan blue coral snake

Palasuberniam, Praneetha and Tan, Kae Yi and Tan, Choo Hock (2021) De novo venom gland transcriptomics of Calliophis bivirgata flaviceps: Uncovering the complexity of toxins from the Malayan blue coral snake. Journal of Venomous Animals and Toxins including Tropical Diseases, 27. ISSN 1678-9199, DOI

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Background: The Malayan blue coral snake, Calliophis bivirgata flaviceps, is a medically important venomous snake in Southeast Asia. However, the complexity and diversity of its venom genes remain little explored. Methods: To address this, we applied high-throughput next-generation sequencing to profile the venom gland cDNA libraries of C. bivirgata flaviceps. The transcriptome was de novo assembled, followed by gene annotation, multiple sequence alignment and analyses of the transcripts. Results: A total of 74 non-redundant toxin-encoding genes from 16 protein families were identified, with 31 full-length toxin transcripts. Three-finger toxins (3FTx), primarily delta-neurotoxins and cardiotoxin-like/cytotoxin-like proteins, were the most diverse and abundantly expressed. The major 3FTx (Cb_FTX01 and Cb_FTX02) are highly similar to calliotoxin, a delta-neurotoxin previously reported in the venom of C. bivirgata. This study also revealed a conserved tyrosine residue at position 4 of the cardiotoxin-like/cytotoxin-like protein genes in the species. These variants, proposed as Y-type CTX-like proteins, are similar to the H-type CTX from cobras. The substitution is conservative though, preserving a less toxic form of elapid CTX-like protein, as indicated by the lack of venom cytotoxicity in previous laboratory and clinical findings. The ecological role of these toxins, however, remains unclear. The study also uncovered unique transcripts that belong to phospholipase A 2 of Groups IA and IB, and snake venom metalloproteinases of PIII subclass, which show sequence variations from those of Asiatic elapids. Conclusion: The venom gland transcriptome of C. bivirgata flaviceps from Malaysia was de novo assembled and annotated. The diversity and expression profile of toxin genes provide insights into the biological and medical importance of the species.

Item Type: Article
Funders: Universiti Malaya [BKS003-2020 & ST011-2020]
Uncontrolled Keywords: Three-finger toxins; Delta-elapitoxin-CB1a; Calliotoxin; Maticotoxin; Snakebite; Envenomation
Subjects: Q Science > QL Zoology
Divisions: Faculty of Medicine
Depositing User: Ms Zaharah Ramly
Date Deposited: 11 Apr 2022 06:32
Last Modified: 11 Apr 2022 06:32

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