Purification and Biochemical Characterization of TsMS 3 and TsMS 4: Neuropeptide-Degrading Metallopeptidases in the Tityus serrulatus Venom

Divergence in toxin antigenicity and venom enzymes in Tityus melici, a medically important scorpion, despite transcriptomic and phylogenetic affinities with problematic Brazilian species

The Brazilian scorpion Tityus melici, native to Minas Gerais and Bahia, is morphologically related to Tityus serrulatus, the most medically significant species in Brazil. Despite inhabiting scorpion-envenomation endemic regions, T. melici venom remains unexplored. This work evaluates T. melici venom composition and function using transcriptomics, enzymatic activities, and in vivo and in vitro immunological analyses. Next-Generation Sequencing unveiled 86 components putatively involved in venom toxicity: 39 toxins, 28 metalloproteases, seven disulfide isomerases, six hyaluronidases, three phospholipases and three amidating enzymes. T. serrulatus showed the highest number of toxin matches with 80-100 % sequence similarity. T. melici is of medical importance as it has a venom LD50 of 0.85 mg/kg in mice. We demonstrated venom phospholipase A2 activity, and elevated hyaluronidase and metalloprotease activities compared to T. serrulatus, paralleling our transcriptomic findings. Comparison of transcriptional levels for T. serrulatus and T. melici venom metalloenzymes suggests species-specific expression patterns in Tityus. Despite close phylogenetic association with T. serrulatus inferred from COI sequences and toxin similarities, partial neutralization of T. melici venom toxicity was achieved when using the anti-T. serrulatus antivenom, implying antigenic divergence among their toxins. We suggest that the Brazilian therapeutic scorpion antivenom could be improved to effectively neutralize T. melici venom.

Proteomic profile of the venom of three dark-colored Tityus (Scorpiones: Buthidae) from the tropical rainforests of Costa Rica

OBJECTIVE

We aimed to elucidate the potential differences in the venom peptide sequences of three Tityus species from Costa Rican rainforests: T. jaimei, T. championi and T. dedoslargos, compared to T. cf. asthenes from Colombia, which could explain the low level of scorpionism in Costa Rica, evidenced by the lack of epidemiological data.

METHODOLOGY

We applied venom proteomics of peptides purified by RP-HPLC and compared the obtained sequences from venoms of these Tityus species to the sequences previously identified from Tityus inhabiting other Central and South American regions.

RESULTS

Venom proteome analysis evidences that most of the putative peptide toxins identified in Costa Rican dark-colored Tityus are very similar to those present in other T. (Atreus) from the region.

CONCLUSIONS

Our study suggests that, in the case of potential envenomation by Tityus in Costa Rica, the same level of toxicity should be observed, compared to other cases caused by members of the subgenus from other geographical localities. On the other hand, compared to countries with more accelerated urban expansion, Costa Rican Tityus still inhabit secondary rainforests and do not commonly share the same spaces with humans, so the lack of epidemiological evidence of medical emergencies caused by envenoming by this scorpion group could be more related to ecological and demographic factors and less attributed to the characteristics of the venom.

Scorpion Venom as a Source of Antimicrobial Peptides: Overview of Biomolecule Separation, Analysis and Characterization Methods

Scorpion venoms have long captivated scientific researchers, primarily due to the potency and specificity of the mechanism of action of their derived components. Among other molecules, these venoms contain highly active compounds, including antimicrobial peptides (AMPs) and ion channel-specific components that selectively target biological receptors with remarkable affinity. Some of these receptors have emerged as prime therapeutic targets for addressing various human pathologies, including cancer and infectious diseases, and have served as models for designing novel drugs. Consequently, extensive biochemical and proteomic investigations have focused on characterizing scorpion venoms. This review provides a comprehensive overview of the key methodologies used in the extraction, purification, analysis, and characterization of AMPs and other bioactive molecules present in scorpion venoms. Noteworthy techniques such as gel electrophoresis, reverse-phase high-performance liquid chromatography, size exclusion chromatography, and "omics" approaches are explored, along with various combinations of methods that enable bioassay-guided venom fractionation. Furthermore, this review presents four adapted proteomic workflows that lead to the comprehensive dissection of the scorpion venom proteome, with an emphasis on AMPs. These workflows differ based on whether the venom is pre-fractionated using separation techniques or is proteolytically digested directly before further proteomic analyses. Since the composition and functionality of scorpion venoms are species-specific, the selection and sequence of the techniques for venom analyses, including these workflows, should be tailored to the specific parameters of the study.

Unraveling and profiling Tityus bahiensis venom: Biochemical analyses of the major toxins

Among the scorpions found in Brazil, Tityus bahiensis is one of the species that causes most of the reported human accidents. In spite of this important constatation, the venom composition description is not available in the literature. Thus, this venom remains not properly studied, segregating this particular species into an abandoned, forgotten condition. In the present study, chromatographic separation (RP-HPLC-C18) and proteomic analyses were employed to unravel the diversity, complexity, and proportional distribution of the main peptides and proteins found in the scorpion venom. Moreover, sequence analyses and the presence of new isoforms and toxins are discussed based on a database comparison with other Tityus toxins. Our results show the presence of a wide diversity of potassium and sodium channel toxins and enzymes, such as metallopeptidases and hyaluronidases, as previously described for other species. However, the current work also describes for the first time, at the protein level, phospholipase, angiotensin-converting enzyme, cysteine-rich proteins, serine peptidase inhibitors peptides, and antimicrobial peptides. Finally, thorough data analyses allowed the description of the venom toxins distribution regarding their diversity and relative quantity. SIGNIFICANCE: The work presents the first Tityus bahiensis proteome. We have focused on describing the neurotoxin variability in terms of their isoforms/amino acid substitutions. Understanding the natural variations in the toxins' sequences is essential, once the affinity of these peptides to their respective receptors/ionic channels will vary depending on the specific peptide sequences. Moreover, the current study describes some proteins present in the venom, including enzymes being described for the first time in scorpion venoms, such as PLA2 and ACE. Moreover, we describe the individual relative quantity distribution for the different protein classes identified, as well as their variability in the T.bahiensis venom. Finally, this study also reports the development of a simple straightforward chromatographic method for scorpion venom fractionation.

Heterologous expression of Ts8, a neurotoxin from Tityus serrulatus venom, evidences its antifungal activity

In this study we expressed the Ts8, a neurotoxin from Tityus serrulatus scorpion venom, in Pichia pastoris yeast. We evaluated the peptide expression in different conditions, such as pH, temperature, and addition of casamino acids supplement. Analyses of expressed products by mass spectrometry and Edman degradation showed that rTs8 has sites that allow its cleavage by yeast proteases released into the culture medium. The casamino acids addition was favourable for toxin expression, however, was not sufficient to minimize proteolytic degradation. Functional assays with recombinant toxin fragments and native toxins have demonstrated the release of cytokines such as TNF-α and IL-1β in some peptides tested. In addition, the toxins were shown to inhibit the Pichia pastoris growth in antifungal test and were not toxic to alveolar macrophages cells at the concentrations analyzed The electrophysiological screening, by voltage clamp technique, showed that the rTs8 fragment with the highest molecular weight inhibited the Kv1.3 channel, whereas the N-terminal fragment had no activity on the ion channels tested.

Leptolysin, a Leptospira secreted metalloprotease of the pappalysin family with broad-spectrum activity

Extracellular proteolytic enzymes are produced by a variety of pathogenic microorganisms, and contribute to host colonization by modulating virulence. Here, we present a first characterization of leptolysin, a Leptospira metalloprotease of the pappalysin family identified in a previous exoproteomic study. Comparative molecular analysis of leptolysin with two other pappalysins from prokaryotes, ulilysin and mirolysin, reveals similarities regarding calcium, zinc, and arginine -binding sites conservation within the catalytic domain, but also discloses peculiarities. Variations observed in the primary and tertiary structures may reflect differences in primary specificities. Purified recombinant leptolysin of L. interrogans was obtained as a ~50 kDa protein. The protease exhibited maximal activity at pH 8.0 and 37°C, and hydrolytic activity was observed in the presence of different salts with maximum efficiency in NaCl. Substrate specificity was assessed using a small number of FRET peptides, and showed a marked preference for arginine residues at the P1 position. L. interrogans leptolysin proteolytic activity on proteinaceous substrates such as proteoglycans and plasma fibronectin was also evaluated. All proteins tested were efficiently degraded over time, confirming the protease´s broad-spectrum activity in vitro. In addition, leptolysin induced morphological alterations on HK-2 cells, which may be partially attributed to extracellular matrix (ECM) degradation. Hemorrhagic foci were observed in the dorsal skin of mice intradermally injected with leptolysin, as a plausible consequence of ECM disarray and vascular endothelium glycocalyx damage. Assuming that leptospiral proteases play an important role in all stages of the infectious process, characterizing their functional properties, substrates and mechanisms of action is of great importance for therapeutic purposes.

Genetic and toxinological divergence among populations of Tityus trivittatus Kraepelin, 1898 (Scorpiones: Buthidae) inhabiting Paraguay and Argentina

Envenoming by scorpions in genus Tityus is a public health problem in Tropical America. One of the most medically significant species is Tityus trivittatus, which is known to occur from southwest Brazil to central-northern and eastern Argentina. In this work, we studied the lethality, composition, antigenicity, and enzymatic activity of venom from a T. trivittatus population found further north in urban areas of eastern Paraguay, where it has caused serious envenomation of children. Our results indicate that the population is of medical importance as it produces a potently toxic venom with an LD50 around 1.19 mg/kg. Venom neutralization in preliminary mouse bioassays was complete when using Brazilian anti-T. serrulatus antivenom but only partial when using Argentinean anti-T. trivittatus antivenom. Venom competitive solid-phase enzyme immunoassays and immunoblotting from Argentinean and Paraguayan T. trivittatus populations indicated that antigenic differences exist across the species range. SDS-PAGE showed variations in type and relative amounts of venom proteins between T. trivitattus samples from Argentina and Paraguay. MALDI-TOF mass spectrometry indicated that while some sodium channel toxins are shared, including β-toxin Tt1g, others are population-specific. Proteolytic activity by zymography and peptide identification through nESI-MS/MS also point out that population-specific proteases may exist in T. trivitattus, which are postulated to be involved in the envenoming process. A time-calibrated molecular phylogeny of mitochondrial COI sequences revealed a significant (8.14%) genetic differentiation between the Argentinean and Paraguayan populations, which appeared to have diverged between the mid Miocene and early Pliocene. Altogether, toxinological and genetic evidence indicate that T. trivitattus populations from Paraguay and Argentina correspond to distinct, unique cryptic species, and suggest that further venom and taxonomic diversity exists in synanthropic southern South American Tityus than previously thought.

Biology, venom composition, and scorpionism induced by brazilian scorpion Tityus stigmurus (Thorell, 1876) (Scorpiones: Buthidae): A mini-review

Scorpionism is a serious public health problem in various regions of the world. In Brazil, a high number of accidents by scorpions have been reported. From 2014 to 2018, about 547,000 cases were recorded, resulting in 466 deaths. The scorpion Tityus stigmurus is the predominant species in the northeast of Brazil, being responsible for most scorpionism cases in this region. With the aid of the transcriptomic approach of the venom gland of this species, components as neurotoxins, antimicrobials, metal chelating peptides and hypotensins, have been identified and characterized in silico, showing different biologic activity in vitro. In addition, the neuronal, pancreatic, renal, and enzymatic effects have been demonstrated for the crude T. stigmurus venom. Therefore, the T. stigmurus scorpion venom constitutes a rich arsenal of bioactive molecules with high potential for therapeutic and biotechnological application.