Three-finger toxins from the venom of Micrurus tschudii tschudii (desert coral snake): Isolation and characterization of tschuditoxin-I

Integrative transcriptomic, proteomic, biochemical and neutralization studies on the venom of Micrurus ephippifer

Species of the genus Micrurus belong to the family Elapidae and possess venoms of significant clinical importance. This study presents an analysis of the venom composition of Micrurus ephippifer, employing transcriptomic and proteomic methodologies. A total of 2885 venom gland transcripts were assembled, of which 42 were identified as toxins. Transcripts for three-finger toxins (3FTx) were the most abundant (80.7 %), followed by PLA2 transcripts (16.3 %). Tryptic peptide sequences obtained through bottom-up shotgun MS/MS venom analysis were assigned to 46 distinct proteins in the SwissProt/UniProt database, of which 23 belong to the 3FTx family. Peptide spectral matching against the venom gland transcriptome database identified 24 proteins, 12 of which correspond to 3FTx, and three belong to PLA2. Venom decomplexation by RP-HPLC followed by N-terminal amino acid sequencing of fractions allowed an estimation of the relative abundance of protein families, indicating that 3FTx comprise over 50 % of the venom. The identified toxic fractions displayed distinct lethality profiles in mice, with certain combinations exhibiting enhanced toxicity, very similar to what has been reported with Brownitoxin-I, with only the PLA2 sequence showing similarity. Our results emphasize the importance of integrating transcriptomic and proteomic approaches to understand venom diversity and its implications for antivenom development. SIGNIFICANCE: Mexico ranks first in the Americas in snake venom diversity. Paradoxically, very little is known about the composition of coral snake venoms, and Micrurus ephippifer is a clear example of this gap, as nothing was known about its venom composition. This type of study provides valuable information that helps fill these knowledge gaps. This study presents the second report of coral snake venoms containing a complex of phospholipase A2 and a three-finger toxin, offering important data that, with further research, will contribute to understanding venom evolution and evaluating the efficacy of antivenoms.

Top-down proteomics of venoms from five Micrurus species from Costa Rica: Comparative composition of phospholipase A2-rich vs three-finger toxin-rich phenotypes

Coralsnakes of the genus Micrurus include more than 80 species distributed in the American continent. They produce potent neurotoxic venoms acting at the neuromuscular junction and potentially leading to respiratory paralysis and death. The vast majority of proteins in coralsnake venoms belong to the three-finger toxin (3FTx) and the group I phospholipase A2 (PLA2) families. Previous studies using 'bottom-up' proteomic strategies have revealed a compositional dichotomy of toxin expression by which different Micrurus species display a predominance of either 3FTx or PLA2 proteins in their venoms, possibly linked to the phylogeographic structure of the genus radiation. 'Top-down' proteomics (TDP) allows the direct analysis of intact proteins in a high resolution mass spectrometer, circumventing the limitations of the 'peptide-to-protein inference problem' inherent to the bottom-up approach. Here, we analyzed the venoms of five out of the six Micrurus species that inhabit Costa Rica, by using a TDP approach. Results unveil venom proteoforms that are shared between these species, and provide additional insights into the variable compositional complexity of these venoms and relationships to their 3FTx/PLA2 dichotomy.

Separation and Analytical Techniques Used in Snake Venomics: A Review Article

The deleterious consequences of snake envenomation are due to the extreme protein complexity of snake venoms. Therefore, the identification of their components is crucial for understanding the clinical manifestations of envenomation pathophysiology and for the development of effective antivenoms. In addition, snake venoms are considered as libraries of bioactive molecules that can be used to develop innovative drugs. Numerous separation and analytical techniques are combined to study snake venom composition including chromatographic techniques such as size exclusion and RP-HPLC and electrophoretic techniques. Herein, we present in detail these existing techniques and their applications in snake venom research. In the first part, we discuss the different possible technical combinations that could be used to isolate and purify SV proteins using what is known as bioassay-guided fractionation. In the second part, we describe four different proteomic strategies that could be applied for venomics studies to evaluate whole venom composition, including the mostly used technique: RP-HPLC. Eventually, we show that to date, there is no standard technique used for the separation of all snake venoms. Thus, different combinations might be developed, taking into consideration the main objective of the study, the available resources, and the properties of the target molecules to be isolated.