Project description:The recent COVID-19 pandemic shows the critical need for novel broad spectrum antiviral agents. Scorpion venoms are known to contain highly bioactive peptides, several of which have demonstrated strong antiviral activity against a range of viruses. We have generated the first annotated reference transcriptome for the Androctonus amoreuxi venom gland and used high performance liquid chromatography, transcriptome mining, circular dichroism and mass spectrometric analysis to purify and characterize twelve previously undescribed venom peptides. Selected peptides were tested for binding to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and inhibition of the spike RBD – human angiotensin-converting enzyme 2 (hACE2) interaction using surface plasmon resonance-based assays. Seven peptides showed dose-dependent inhibitory effects, albeit with IC50 in the high micromolar range (117–1202 μM). The most active peptide was synthesized using solid phase peptide synthesis and tested for its antiviral activity against SARS-CoV-2 (Lineage B.1.1.7). On exposure to the synthetic peptide of a human lung cell line infected with replication-competent SARS-CoV-2, we observed an IC50 of 200 nM, which was nearly 600-fold lower than that observed in the RBD – hACE2 binding inhibition assay. Our results show that scorpion venom peptides can inhibit the SARS-CoV-2 replication although unlikely through inhibition of spike RBD – hACE2 interaction as the primary mode of action. Scorpion venom peptides represent excellent scaffolds for design of novel anti-SARS-CoV-2 constrained peptides. Future studies should fully explore their antiviral mode of action as well as the structural dynamics of inhibition of target virus-host interactions.
Project description:Both single cell and bulk RNA sequencing was performed on expanding or differentiating snake venom gland organoids (from Aspidelaps Lubricus Cowlesi and Naja Nivea), or tissue (Aspidelaps Lubricus Cowlesi). Bulk RNA sequencing from the snake venom gland, liver and pancreas was performed to construct a de novo transcriptome using Trinity.
Project description:Many peptides in scorpion venoms are amidated at their C-termini. This post-translational modification is paramount for the correct biological function of ion channel toxins and antimicrobial peptides, among others. The discovery of canonical amidation sequences in transcriptome-derived scorpion proproteins suggests that a conserved enzymatic α-amidation system must be responsible for this modification of scorpion peptides. A transcriptomic approach was employed to identify sequences putatively encoding enzymes of the α-amidation pathway. A dual enzymatic α-amidation system was found, consisting of the membrane-anchored, bifunctional, peptidylglycine α-amidating monooxygenase (PAM) and its paralogs, soluble monofunctional peptidylglycine α-hydroxylating monooxygenase (PHMm) and peptidyl-α-hydroxyglycine α-amidating lyase (PALm). Independent genes encode these three enzymes. Amino acid residues responsible for ion coordination and enzymatic activity are conserved in these sequences, suggesting that the enzymes are functional. Potential endoproteolytic recognition sites for proprotein convertases in the PAM sequence indicate that PAM-derived soluble isoforms may also be expressed. Sequences potentially encoding proprotein convertases (PC1 and PC2), carboxypeptidase E (CPE), and other enzymes of the α-amidation pathway, were also found, confirming the presence of this pathway in scorpions.
Project description:We used a combined transcriptomic and proteomic approach to characterize the venom of a male and female of the black-back scorpion (Hadrurus spadix).
Project description:Heloderma horridum horridum commonly known as the scorpion lizard, Mexican scorpion, and beaded lizard, is a venomous reptile native of America. The venom derived from this lizard has potential applications, particularly in treatment of type II diabetes through the peptide Exendin. In this work, H. h. horridum venom was extracted from adult specimens and lyophilized. To characterize the venom, enzymatic assays, including hyaluronidase, phospholipase A2, and proteolytic activity were conducted. A proteomic analysis of the venom was also performed employing bottom-up/shotgun approaches from SDS-PAGE and High pH Reversed-Phase chromatography., besides fractionation of tryptic peptides using a nano-LC-MS/MS. These approaches involved massive sequencing to enhancing the likelihood of detecting an extensive range of venom proteins. The proteins and peptides found in H. h. horridum venom are reviewed according to the classification of the transcriptome previously reported.
Project description:The scorpion Leiurus quinquestriatus quinquestriatus, popularly known as the Palestinian yellow scorpion or as Deathstalker, has one of the most potent venoms and is of great medical importance, especially in regions of North Africa and the Middle East, but there is little knowledge about its composition. The biochemical profile of its venom is extremely valuable for understanding the envenomation, as well as for the production of the serum. 32 fractions were isolated by RP-HPLC, which were analyzed by proteomics analisys, which identified 203 peaks, of which the diversity presented with greater components of peptides acting on sodium channels (63%), potassium (25%), chlorine (1%) and calcium (1%).