The Enzymatic Core of Scorpion Venoms.

Enzymes are an integral part of animal venoms. Unlike snakes, in which enzymes play a primary role in envenomation, in scorpions, their function appears to be ancillary in most species. Due to this, studies on the diversity of scorpion venom components have focused primarily on the peptides responsible for envenomation (toxins) and a few others (e.g., antimicrobials), while enzymes have been overlooked. In this work, a comprehensive study on enzyme diversity in scorpion venoms was performed by transcriptomic and proteomic techniques. Enzymes of 63 different EC types were found, belonging to 330 orthogroups. Of them, 24 ECs conform the scorpion venom enzymatic core, since they were determined to be present in all the studied scorpion species. Transferases and lyases are reported for the first time. Novel enzymes, which can play different roles in the venom, including direct toxicity, as venom spreading factors, activators of venom components, venom preservatives, or in prey pre-digestion, were described and annotated. The expression profile for transcripts coding for venom enzymes was analyzed, and shown to be similar among the studied species, while being significantly different from their expression pattern outside the telson.

Scorpion venomics: a 2019 overview.

Introduction: A few scorpions are dangerous to humans. Their medical relevance was the initial driving force for venom research. By classical biochemistry and molecular cloning, several venom peptides and their coding transcripts were characterized, mainly those related to toxins. The discovery of other components with novel activities and potential applications has revitalized the interest in the field in the last decade and a half. Nontoxic scorpion species have also attracted major interest.Areas covered: Advances in the identification of scorpion venom components via high-throughput venomics (genomics, transcriptomics and proteomics) up to 2019 are summarized. A classification system for venom-related transcripts and proteins, together with an intuitive systematic nomenclature for RNAseq-generated transcripts are proposed. Venom components classified as Na+, K+, Ca2+, Cl- and TRP channel toxins, enzymes, protease inhibitors, host defense peptides and other peptidic molecules are briefly reviewed, giving a comprehensive picture of the venom.Expert opinion: Modern high-throughput technologies applied to scorpion venom studies have resulted in a dramatic increase in both, the number and diversity of available sequences, leading to a deeper understanding of the composition of scorpion venoms. Still, many newly-discovered venom constituents remain to be characterized, to complete the puzzle of scorpion venoms.

Dissecting Toxicity: The Venom Gland Transcriptome and the Venom Proteome of the Highly Venomous Scorpion Centruroides limpidus (Karsch, 1879).

Venom glands and soluble venom from the Mexican scorpion Centruroides limpidus (Karsch, 1879) were used for transcriptomic and proteomic analyses, respectively. An RNA-seq was performed by high-throughput sequencing with the Illumina platform. Approximately 80 million reads were obtained and assembled into 198,662 putative transcripts, of which 11,058 were annotated by similarity to sequences from available databases. A total of 192 venom-related sequences were identified, including Na+ and K+ channel-acting toxins, enzymes, host defense peptides, and other venom components. The most diverse transcripts were those potentially coding for ion channel-acting toxins, mainly those active on Na+ channels (NaScTx). Sequences corresponding to ß- scorpion toxins active of K+ channels (KScTx) and λ-KScTx are here reported for the first time for a scorpion of the genus Centruroides. Mass fingerprint corroborated that NaScTx are the most abundant components in this venom. Liquid chromatography coupled to mass spectometry (LC-MS/MS) allowed the identification of 46 peptides matching sequences encoded in the transcriptome, confirming their expression in the venom. This study corroborates that, in the venom of toxic buthid scorpions, the more abundant and diverse components are ion channel-acting toxins, mainly NaScTx, while they lack the HDP diversity previously demonstrated for the non-buthid scorpions. The highly abundant and diverse antareases explain the pancreatitis observed after envenomation by this species.

The diversity of venom components of the scorpion species Paravaejovis schwenkmeyeri (Scorpiones: Vaejovidae) revealed by transcriptome and proteome analyses.

The recent publication of high-throughput transcriptomic and proteomic analyses of scorpion venom glands has increased our knowledge on the biodiversity of venom components. In this contribution, we report the transcriptome of the venom gland and the proteome of the venom for the scorpion species Paravaejovis schwenkmeyeri, a member of the family Vaejovidae. We report 138 annotated transcripts encoding putative peptides/proteins with sequence identity to known venom components available from different databases. A fingerprint analysis containing the molecular masses of 212 components of the whole soluble venom revealed molecular weights of approximately 700 to 13,800 Da, with most detected proteins ranging from 1500 to 3000 Da. Amino acid sequencing of venom components by LC-MS/MS allowed the identification of fragments from 27 peptides encoded by transcripts found in the transcriptome analysis. Enzymatic assays conducted with the soluble venom fraction confirmed the presence of enzymes such as hyaluronidases and phospholipases. The database presented here increases our general knowledge on the biodiversity of venom components from neglected non-buthid scorpions.

Venom gland transcriptomic and venom proteomic analyses of the scorpion Megacormus gertschi Díaz-Najera, 1966 (Scorpiones: Euscorpiidae: Megacorminae).

The soluble venom from the Mexican scorpion Megacormus gertschi of the family Euscorpiidae was obtained and its biological effects were tested in several animal models. This venom is not toxic to mice at doses of 100 µg per 20 g of mouse weight, while being lethal to arthropods (insects and crustaceans), at doses of 20 µg (for crickets) and 100 µg (for shrimps) per animal. Samples of the venom were separated by high performance liquid chromatography and circa 80 distinct chromatographic fractions were obtained from which 67 components have had their molecular weights determined by mass spectrometry analysis. The N-terminal amino acid sequence of seven protein/peptides were obtained by Edman degradation and are reported. Among the high molecular weight components there are enzymes with experimentally-confirmed phospholipase activity. A pair of telsons from this scorpion species was dissected, from which total RNA was extracted and used for cDNA library construction. Massive sequencing by the Illumina protocol, followed by de novo assembly, resulted in a total of 110,528 transcripts. From those, we were able to annotate 182, which putatively code for peptides/proteins with sequence similarity to previously-reported venom components available from different protein databases. Transcripts seemingly coding for enzymes showed the richest diversity, with 52 sequences putatively coding for proteases, 20 for phospholipases, 8 for lipases and 5 for hyaluronidases. The number of different transcripts potentially coding for peptides with sequence similarity to those that affect ion channels was 19, for putative antimicrobial peptides 19, and for protease inhibitor-like peptides, 18. Transcripts seemingly coding for other venom components were identified and described. The LC/MS analysis of a trypsin-digested venom aliquot resulted in 23 matches with the translated transcriptome database, which validates the transcriptome. The proteomic and transcriptomic analyses reported here constitute the first approach to study the venom components from a scorpion species belonging to the family Euscorpiidae. The data certainly show that this venom is different from all the ones described thus far in the literature.

Venom Gland Transcriptomic and Proteomic Analyses of the Enigmatic Scorpion Superstitionia donensis (Scorpiones: Superstitioniidae), with Insights on the Evolution of Its Venom Components.

Venom gland transcriptomic and proteomic analyses have improved our knowledge on the diversity of the heterogeneous components present in scorpion venoms. However, most of these studies have focused on species from the family Buthidae. To gain insights into the molecular diversity of the venom components of scorpions belonging to the family Superstitioniidae, one of the neglected scorpion families, we performed a transcriptomic and proteomic analyses for the species Superstitionia donensis. The total mRNA extracted from the venom glands of two specimens was subjected to massive sequencing by the Illumina protocol, and a total of 219,073 transcripts were generated. We annotated 135 transcripts putatively coding for peptides with identity to known venom components available from different protein databases. Fresh venom collected by electrostimulation was analyzed by LC-MS/MS allowing the identification of 26 distinct components with sequences matching counterparts from the transcriptomic analysis. In addition, the phylogenetic affinities of the found putative calcins, scorpines, La1-like peptides and potassium channel κ toxins were analyzed. The first three components are often reported as ubiquitous in the venom of different families of scorpions. Our results suggest that, at least calcins and scorpines, could be used as molecular markers in phylogenetic studies of scorpion venoms.