Identification of an antiviral component from the venom of the scorpion Liocheles australasiae using transcriptomic and mass spectrometric analyses

Identification and synthesis of a long-chain antimicrobial peptide from the venom of the Liocheles australasiae scorpion

Scorpion venom contains linear peptides without disulfide bonds in addition to peptides with disulfide bonds. Many such linear peptides have an amphiphilic α-helical structure, often with antimicrobial activity and can be classified into three groups based on their molecular size. Among them, long-chain antimicrobial peptides consisting of more than 40 residues have not been thoroughly studied due to the difficulty of synthesizing them. We have previously reported a transcriptome analysis of the venom gland of Liocheles australasiae that revealed precursor sequences of long-chain antimicrobial peptides. In the study reported here, we identified the mature structure of one such long-chain antimicrobial peptide, LaCT1, which we synthesized using chemical ligation to confirm its structure and evaluate its biological activities. The result showed that LaCT1 exhibited significant antimicrobial activity. In addition, we identified its partial peptides consisting of an N- or C-terminal region, which may be generated by enzymatic cleavage in the venom. Among them, only the peptide containing the N-terminal half region was active. LaCT1 also not only showed insecticidal activity but also synergistically enhanced the effects of another insecticidal peptide identified in L. australasiae venom as well. These results provide insights into the role of antimicrobial peptides in scorpion venom.

Exploiting venom toxins in paratransgenesis to prevent mosquito-borne disease

Mosquitoes are responsible for the transmission of numerous pathogens, including Plasmodium parasites, arboviruses and filarial worms. They pose a significant risk to public health with over 200 million cases of malaria per annum and approximately 4 billion people at risk of arthropod-borne viruses (arboviruses). Mosquito populations are geographically expanding into temperate regions and their distribution is predicted to continue increasing. Mosquito symbionts, including fungi, bacteria and viruses, have desirable traits for mosquito disease control including spreading horizontally and vertically through mosquito populations and potentially colonising multiple important vector species. Paratransgenesis, genetic modification of mosquito symbionts with effectors to target the pathogen rather than the vector, is a promising strategy to prevent the spread of mosquito-borne diseases. A variety of effectors can be expressed but venom toxins are excellent effector candidates because they are target specific, potent and stable. However, the only toxins to be explored in mosquito paratransgenesis to date are scorpine and mutated phospholipase A2. To enhance the scope, effectiveness and durability of paratransgenesis, an expanded arsenal of effectors is required. This review discusses other potential toxin effectors for future paratransgenesis studies based on prior in vitro and in vivo antiparasitic and antiviral studies and highlights the need for further research and investment in this area. In terms of mosquito-borne diseases, paratransgenesis strategies have been developed to target Plasmodium. We postulate the potential to apply this principle to target arboviruses using antiviral toxin effectors.

Discovery of a Novel Insecticidal Peptide with a Cystine-Stabilized α-Helix/α-Helix Motif from the Venom of Scorpion Liocheles australasiae

Scorpion venom contains various bioactive peptides, many of which exhibit insecticidal activity. The majority of these peptides have a cystine-stabilized α-helix/β-sheet (CSαβ) motif. In addition to these peptides, scorpion venom also contains those with a cystine-stabilized α-helix/α-helix (CSαα) motif, which are known as κ-KTx peptides. Some of these peptides show weak inhibitory activity on mammal potassium channels, but, in many cases, their biological activity remained unknown. In this study, with the aim of discovering novel insecticidal peptides, we synthesized five peptides, which were predicted to adopt a CSαα motif, identified from the venom of the scorpion Liocheles australasiae, and measured their insecticidal activity. As a result, one of the peptides, named LaIT5, exhibited significant insecticidal activity. To the best of our knowledge, this is the first report of insecticidal peptides with a CSαα motif. Furthermore, we synthesized its analogs based on sequence comparisons with other inactive CSαα-motif peptides to identify amino acid residues important for its insecticidal activity. The results indicate that two consecutive His residues at the central region of LaIT5 are particularly important for the activity. Since LaIT5 did not show any toxicity against mice, it was concluded that its action is selective for insects.

Profiling the Linear Peptides of Venom from the Brazilian Scorpion Tityus serrulatus: Structural and Functional Characterization

Scorpion venoms are a rich source of bioactive peptides, most of which are neurotoxic, with 30 to 70 amino acid residues in their sequences. There are a scarcity of reports in the literature concerning the short linear peptides found in scorpion venoms. This type of peptide toxin may be selectively extracted from the venom using 50% (v/v) acetonitrile. The use of LC-MS and MS/MS enabled the detection of 12 bioactive short linear peptides, of which six were identified as cryptides. These peptides were shown to be multifunctional, causing hemolysis, mast cell degranulation and lysis, edema, pain, and anxiety, increasing the complexity of the envenomation mechanism. Apparently, the natural functions of these peptide toxins are to induce inflammation and discomfort in the victims of scorpion stings.

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.

Cysteine-rich peptides: From bioactivity to bioinsecticide applications

Greater levels of insect resistance and constraints on the use of current pesticides have recently led to increased crop losses in agricultural production. Further, the health and environmental impacts of pesticides now restrict their application. Biologics based on peptides are gaining popularity as efficient crop protection agents with low environmental toxicity. Cysteine-rich peptides (whether originated from venoms or plant defense substances) are chemically stable and effective as insecticides in agricultural applications. Cysteine-rich peptides fulfill the stability and efficacy requirements for commercial uses and provide an environmentally benign alternative to small-molecule insecticides. In this article, cysteine-rich insecticidal peptide classes identified from plants and venoms will be highlighted, focusing on their structural stability, bioactivity and production.

Antimicrobial Activity Developed by Scorpion Venoms and Its Peptide Component

Microbial infections represent a problem of great importance at the public health level, with a high rate of morbidity-mortality worldwide. However, treating the different diseases generated by microorganisms requires a gradual increase in acquired resistance when applying or using them against various antibiotic therapies. Resistance is caused by various molecular mechanisms of microorganisms, thus reducing their effectiveness. Consequently, there is a need to search for new opportunities through natural sources with antimicrobial activity. One alternative is using peptides present in different scorpion venoms, specifically from the Buthidae family. Different peptides with biological activity in microorganisms have been characterized as preventing their growth or inhibiting their replication. Therefore, they represent an alternative to be used in the design and development of new-generation antimicrobial drugs in different types of microorganisms, such as bacteria, fungi, viruses, and parasites. Essential aspects for its disclosure, as shown in this review, are the studies carried out on different types of peptides in scorpion venoms with activity against pathogenic microorganisms, highlighting their high therapeutic potential.

Antiviral Effects of Animal Toxins: Is There a Way to Drugs?

Viruses infect all types of organisms, causing viral diseases, which are very common in humans. Since viruses use the metabolic pathways of their host cells to replicate, they are difficult to eradicate without affecting the cells. The most effective measures against viral infections are vaccinations and antiviral drugs, which selectively inhibit the viral replication cycle. Both methods have disadvantages, which requires the development of new approaches to the treatment of viral diseases. In the study of animal venoms, it was found that, in addition to toxicity, venoms exhibit other types of biological activity, including an antiviral one, the first mention of which dates back to middle of the last century, but detailed studies of their antiviral activity have been conducted over the past 15 years. The COVID-19 pandemic has reinforced these studies and several compounds with antiviral activity have been identified in venoms. Some of them are very active and can be considered as the basis for antiviral drugs. This review discusses recent antiviral studies, the found compounds with high antiviral activity, and the possible mechanisms of their action. The prospects for using the animal venom components to create antiviral drugs, and the expected problems and possible solutions are also considered.

Two new cationic α-helical peptides identified from the venom gland of Liocheles australasiae possess antimicrobial activity against methicillin-resistant staphylococci

Methicillin-resistant staphylococci have become growing threats to human health, and novel antimicrobials are urgently needed. Natural antimicrobial peptides (AMPs) are promising alternatives to traditional antibiotics. Here, two novel cationic α-helical antimicrobial peptides, Lausporin-1 and Lausporin-2, were identified from the venom gland of the scorpion L. australasiae through a cDNA library screening strategy. Biochemical analyses demonstrated that Lausporin-1 and Lausporin-2 are cationic α-helical amphipathic molecules. Antimicrobial assays demonstrated that the two peptides possess antibacterial activities against several species of antibiotic-resistant staphylococci. Importantly, they are active against methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus capitis, with the minimum inhibitory concentrations ranging from 2.5 to 10 μg/ml. Moreover, both peptides can induce dose-dependent plasma membrane disruptions of the bacteria. In short, our work expands the knowledge of the scorpion L. australasiae venom-derived AMPs and sheds light on the potential of Lausporin-1 and Lausporin-2 in the development of novel drugs against methicillin-resistant staphylococci.