Cone Snails: A Big Store of Conotoxins for Novel Drug Discovery

Systemic antihyperalgesic effect of a novel conotoxin from Californiconus californicus in an inflammatory pain model

Introduction

This study explores the analgesic potential of the novel conotoxin O1_cal6.4b, derived from Californiconus californicus, as a candidate for pain management in a model of inflammatory pain.

Methods

O1_cal6.4b was systemically administered to Wistar rats, and its effects on thermal hyperalgesia and motor coordination were evaluated. Comparative analyses were conducted against O1_cal6.4d, ω-MVIIA, and standard analgesics (morphine, dexamethasone, and diclofenac). Structural differences between O1_cal6.4b and O1_cal6.4d were examined using in silico modeling and molecular dynamics simulations.

Results

Systemic administration of O1_cal6.4b significantly reduced thermal hyperalgesia in a dose-dependent manner without impairing motor coordination. The analgesic effect of O1_cal6.4b was superior to that of O1_cal6.4d, ω-MVIIA, and standard analgesics. Structural analyses revealed notable differences between O1_cal6.4b and O1_cal6.4d, suggesting unique functional properties.

Discussion

The findings indicate that O1_cal6.4b exhibits a promising analgesic profile with advantages over traditional opioid-based therapies. These results underscore the molecular diversity of conotoxins and highlight their potential as innovative analgesic treatments. Further research is needed to elucidate the mechanism of action of this novel conotoxin.

In silico toxicology investigation of μ-conotoxin KIIIA on human Na+ channel Nav1.2

Conotoxins(CTXs) can specifically act on multiple ion channels, which are crucial for the development of neurobiology and novel targeted drug development. At present, >10,000 kinds of CTXs have been sequenced, it would be extremely laborious to conduct experiments for each. μ-CTX KIIIA is a type of substance that can selectively recognize voltage-gated sodium ion channels. This article constructs four derivatives of KIIIA and predicts their 3D structures; afterwards, their molecular orbital arrangements and physicochemical properties were calculated using DFT; then, predicted their toxicokinetic parameters such as absorption, distribution, metabolism, excretion (ADME) and toxicity (T) through Machine Learning (ML); finally, molecular docking and molecular dynamics are used to investigate the interaction modes and binding affinity. The results indicate that the toxicity of KIIIA and its derivatives (KIIIA-1 -KIIIA-4) to the human body is mainly concentrated in the liver and respiratory tract. Among four derivatives, KIIIA-2 (5 Ser → Arg) has better toxicokinetics properties and its binding energy to Nav1.2 is -65.32 kcal/mol, which is higher than that of wild type(-32.13 kcal/mol). This study indicate that computational toxicology can facilitate the druggability research of CTXs, and KIIIA-2 can be developed as a potential antiepileptic drug.

Marine-derived bioactive compounds for neuropathic pain: pharmacology and therapeutic potential

Neuropathic pain, a challenging condition often associated with diabetes, trauma, or chemotherapy, impairs patients' quality of life. Current treatments often provide inconsistent relief and notable adverse effects, highlighting the urgent need for safer and more effective alternatives. This review investigates marine-derived bioactive compounds as potential novel therapies for neuropathic pain management. Marine organisms, including fungi, algae, cone snails, sponges, soft corals, tunicates, and fish, produce a diverse range of secondary metabolites with significant pharmacological properties. These include peptides (e.g., conopeptides, piscidin 1), non-peptides (e.g., guanidinium toxins, astaxanthin, docosahexaenoic acid, fucoidan, apigenin, fumagillin, aaptamine, flexibilide, excavatolide B, capnellenes, austrasulfones, lemnalol), and crude extracts (e.g., Spirulina platensis, Dunaliella salina, Cliothosa aurivilli). These compounds exhibit diverse mechanisms of action, such as modulating ion channels (e.g., transient receptor potential channels, voltage-gated sodium, calcium, and potassium channels, and G protein-coupled inwardly rectifying potassium channels), interacting with cell-surface receptors (e.g., nicotinic acetylcholine, NMDA, kainate, GABAB​, and neurotensin receptors), inhibiting norepinephrine transporters, reducing oxidative stress, and attenuating neuroinflammation. These effects collectively contribute to alleviating nerve degeneration and symptoms of neuropathic pain, including hyperalgesia, allodynia, and associated psychomotor disturbances. Marine-derived bioactive compounds represent promising alternatives to conventional neuropathic pain treatments, to advance their development and assess their integration into neuropathic pain management strategies.

ConoDL: a deep learning framework for rapid generation and prediction of conotoxins

Conotoxins, being small disulfide-rich and bioactive peptides, manifest notable pharmacological potential and find extensive applications. However, the exploration of conotoxins' vast molecular space using traditional methods is severely limited, necessitating the urgent need of developing novel approaches. Recently, deep learning (DL)-based methods have advanced to the molecular generation of proteins and peptides. Nevertheless, the limited data and the intricate structure of conotoxins constrain the application of deep learning models in the generation of conotoxins. We propose ConoDL, a framework for the generation and prediction of conotoxins, comprising the end-to-end conotoxin generation model (ConoGen) and the conotoxin prediction model (ConoPred). ConoGen employs transfer learning and a large language model (LLM) to tackle the challenges in conotoxin generation. Meanwhile, ConoPred filters artificial conotoxins generated by ConoGen, narrowing down the scope for subsequent research. A comprehensive evaluation of the peptide properties at both sequence and structure levels indicates that the artificial conotoxins generated by ConoDL exhibit a certain degree of similarity to natural conotoxins. Furthermore, ConoDL has generated artificial conotoxins with novel cysteine scaffolds. Therefore, ConoDL may uncover new cysteine scaffolds and conotoxin molecules, facilitating further exploration of the molecular space of conotoxins and the discovery of pharmacologically active variants.

In Silico Conotoxin Studies: Progress and Prospects

Cone snails of the genus Conus have evolved to produce structurally distinct and functionally diverse venom peptides for defensive and predatory purposes. This nature-devised delicacy enlightened drug discovery and for decades, the bioactive cone snail venom peptides, known as conotoxins, have been widely explored for their therapeutic potential, yet we know very little about them. With the augmentation of computational algorithms from the realms of bioinformatics and machine learning, in silico strategies have made substantial contributions to facilitate conotoxin studies although still with certain limitations. In this review, we made a bibliometric analysis of in silico conotoxin studies from 2004 to 2024 and then discussed in silico strategies to not only efficiently classify conotoxin superfamilies but also speed up drug discovery from conotoxins, reveal binding modes of known conotoxin-ion channel interactions at a microscopic level and relate the mechanisms of ion channel modulation to its underlying molecular structure. We summarized the current progress of studies in this field and gave an outlook on prospects.

A review on inflammation modulating venom proteins/peptide therapeutics and their delivery strategies: A review

Inflammation is an initial biological reaction that occurs in response to infection caused by foreign pathogens or injury. This process involves a tightly controlled series of signaling events at the molecular and cellular levels, with the ultimate goal of restoring tissue balance and protecting against invading pathogens. Malfunction in the process of inflammation can result in a diverse array of diseases, such as cardiovascular, neurological, and autoimmune disorders. Therefore, the management of inflammation is of utmost importance in modern medicine. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids have long been the mainstays of pharmacological treatment for inflammation, effectively alleviating symptoms in many patients. Recently, toxins and venom, formerly seen as mostly harmful to the human body, have been recognized as possible medicinal substances for treating inflammation. Organisms that are venomous, such as spiders, scorpions, snakes, and certain marine species, have developed a wide range of powerful toxins that can effectively disable or discourage predators. Remarkably, the majority of these poisons and venoms consist of proteins and peptides, which are acknowledged as significant bioactive compounds with medicinal potential. The goal of this review is to investigate the medicinal potential of peptides derived from venoms and their complex mechanism of action in suppressing inflammation. This review also discusses various challenges and future prospects for effective venom delivery.

Voltage-Gated K+ Channel Modulation by Marine Toxins: Pharmacological Innovations and Therapeutic Opportunities

Bioactive compounds are abundant in animals originating from marine ecosystems. Ion channels, which include sodium, potassium, calcium, and chloride, together with their numerous variants and subtypes, are the primary molecular targets of the latter. Based on their cellular targets, these venom compounds show a range of potencies and selectivity and may have some therapeutic properties. Due to their potential as medications to treat a range of (human) diseases, including pain, autoimmune disorders, and neurological diseases, marine molecules have been the focus of several studies over the last ten years. The aim of this review is on the various facets of marine (or marine-derived) molecules, ranging from structural characterization and discovery to pharmacology, culminating in the development of some "novel" candidate chemotherapeutic drugs that target potassium channels.

Chemical Synthesis and Insecticidal Activity Research Based on α-Conotoxins

The escalating resistance of agricultural pests to chemical insecticides necessitates the development of novel, efficient, and safe biological insecticides. Conus quercinus, a vermivorous cone snail, yields a crude venom rich in peptides for marine worm predation. This study screened six α-conotoxins with insecticidal potential from a previously constructed transcriptome database of C. quercinus, characterized by two disulfide bonds. These conotoxins were derived via solid-phase peptide synthesis (SPPS) and folded using two-step iodine oxidation for further insecticidal activity validation, such as CCK-8 assay and insect bioassay. The final results confirmed the insecticidal activities of the six α-conotoxins, with Qc1.15 and Qc1.18 exhibiting high insecticidal activity. In addition, structural analysis via homology modeling and functional insights from molecular docking offer a preliminary look into their potential insecticidal mechanisms. In summary, this study provides essential references and foundations for developing novel insecticides.

Peptide Toxins from Antarctica: The Nemertean Predator and Scavenger Parborlasia corrugatus (McIntosh, 1876)

Peptide toxins from marine invertebrates have found use as drugs and in biotechnological applications. Many marine habitats, however, remain underexplored for natural products, and the Southern Ocean is among them. Here, we report toxins from one of the top predators in Antarctic waters: the nemertean worm Parborlasia corrugatus (McIntosh, 1876). Transcriptome mining revealed a total of ten putative toxins with a cysteine pattern similar to that of alpha nemertides, four nemertide-beta-type sequences, and two novel full-length parborlysins. Nemertean worms express toxins in the epidermal mucus. Here, the expression was determined by liquid chromatography combined with mass spectrometry. The findings include a new type of nemertide, 8750 Da, containing eight cysteines. In addition, we report the presence of six cysteine-containing peptides. The toxicity of tissue extracts and mucus fractions was tested in an Artemia assay. Notably, significant activity was observed both in tissue and the high-molecular-weight mucus fraction, as well as in a parborlysin fraction. Membrane permeabilization experiments display the membranolytic activity of some peptides, most prominently the parborlysin fraction, with an estimated EC50 of 70 nM.

Nutraceutical and Medicinal Importance of Marine Molluscs

Marine molluscs are of enormous scientific interest due to their astonishing diversity in terms of their size, shape, habitat, behaviour, and ecological roles. The phylum Mollusca is the second most common animal phylum, with 100,000 to 200,000 species, and marine molluscs are among the most notable class of marine organisms. This work aimed to show the importance of marine molluscs as a potential source of nutraceuticals as well as natural medicinal drugs. In this review, the main classes of marine molluscs, their chemical ecology, and the different techniques used for the extraction of bioactive compounds have been presented. We pointed out their nutraceutical importance such as their proteins, peptides, polysaccharides, lipids, polyphenolic compounds pigments, marine enzymes, minerals, and vitamins. Their pharmacological activities include antimicrobial, anticancer, antioxidant, anti-inflammatory, and analgesic activities. Moreover, certain molluscs like abalones and mussels contain unique compounds with potential medicinal applications, ranging from wound healing to anti-cancer effects. Understanding the nutritional and therapeutic value of marine molluscs highlights their significance in both pharmaceutical and dietary realms, paving the way for further research and utilization in human health.

Potential New Therapies "ROS-Based" in CLL: An Innovative Paradigm in the Induction of Tumor Cell Apoptosis

Chronic lymphocytic leukemia, in spite of recent advancements, is still an incurable disease; the majority of patients eventually acquire resistance to treatment through relapses. In all subtypes of chronic lymphocytic leukemia, the disruption of normal B-cell homeostasis is thought to be mostly caused by the absence of apoptosis. Consequently, apoptosis induction is crucial to the management of this illness. Damaged biological components can accumulate as a result of the oxidation of intracellular lipids, proteins, and DNA by reactive oxygen species. It is possible that cancer cells are more susceptible to apoptosis because of their increased production of reactive oxygen species. An excess of reactive oxygen species can lead to oxidative stress, which can harm biological elements like DNA and trigger apoptotic pathways that cause planned cell death. In order to upset the balance of oxidative stress in cells, recent therapeutic treatments in chronic lymphocytic leukemia have focused on either producing reactive oxygen species or inhibiting it. Examples include targets created in the field of nanomedicine, natural extracts and nutraceuticals, tailored therapy using biomarkers, and metabolic targets. Current developments in the complex connection between apoptosis, particularly ferroptosis and its involvement in epigenomics and alterations, have created a new paradigm.

Predatory and Defensive Strategies in Cone Snails

Cone snails are carnivorous marine animals that prey on fish (piscivorous), worms (vermivorous), or other mollusks (molluscivorous). They produce a complex venom mostly made of disulfide-rich conotoxins and conopeptides in a compartmentalized venom gland. The pharmacology of cone snail venom has been increasingly investigated over more than half a century. The rising interest in cone snails was initiated by the surprising high human lethality rate caused by the defensive stings of some species. Although a vast amount of information has been uncovered on their venom composition, pharmacological targets, and mode of action of conotoxins, the venom-ecology relationships are still poorly understood for many lineages. This is especially important given the relatively recent discovery that some species can use different venoms to achieve rapid prey capture and efficient deterrence of aggressors. Indeed, via an unknown mechanism, only a selected subset of conotoxins is injected depending on the intended purpose. Some of these remarkable venom variations have been characterized, often using a combination of mass spectrometry and transcriptomic methods. In this review, we present the current knowledge on such specific predatory and defensive venoms gathered from sixteen different cone snail species that belong to eight subgenera: Pionoconus, Chelyconus, Gastridium, Cylinder, Conus, Stephanoconus, Rhizoconus, and Vituliconus. Further studies are needed to help close the gap in our understanding of the evolved ecological roles of many cone snail venom peptides.

Diversity and Evolutionary Analysis of Venom Insulin Derived from Cone Snails

Cone snails possess a diverse array of novel peptide toxins, which selectively target ion channels and receptors in the nervous and cardiovascular systems. These numerous novel peptide toxins are a valuable resource for future marine drug development. In this review, we compared and analyzed the sequence diversity, three-dimensional structural variations, and evolutionary aspects of venom insulin derived from different cone snail species. The comparative analysis reveals that there are significant variations in the sequences and three-dimensional structures of venom insulins from cone snails with different feeding habits. Notably, the venom insulin of some piscivorous cone snails exhibits a greater similarity to humans and zebrafish insulins. It is important to emphasize that these venom insulins play a crucial role in the predatory strategies of these cone snails. Furthermore, a phylogenetic tree was constructed to trace the lineage of venom insulin sequences, shedding light on the evolutionary interconnections among cone snails with diverse diets.

Systematic dissection of genomic features determining the vast diversity of conotoxins

BACKGROUND

Conus, a highly diverse species of venomous predators, has attracted significant attention in neuroscience and new drug development due to their rich collection of neuroactive peptides called conotoxins. Recent advancements in transcriptome, proteome, and genome analyses have facilitated the identification of conotoxins within Conus' venom glands, providing insights into the genetic features and evolutionary patterns of conotoxin genes. However, the underlying mechanism behind the extraordinary hypervariability of conotoxins remains largely unknown.

RESULTS

We analyzed the transcriptomes of 34 Conus species, examining various tissues such as the venom duct, venom bulb, and salivary gland, leading to the identification of conotoxin genes. Genetic variation analysis revealed that a subset of these genes (15.78% of the total) in Conus species underwent positive selection (Ka/Ks > 1, p < 0.01). Additionally, we reassembled and annotated the genome of C. betulinus, uncovering 221 conotoxin-encoding genes. These genes primarily consisted of three exons, with a significant portion showing high transcriptional activity in the venom ducts. Importantly, the flanking regions and adjacent introns of conotoxin genes exhibited a higher prevalence of transposon elements, suggesting their potential contribution to the extensive variability observed in conotoxins. Furthermore, we detected genome duplication in C. betulinus, which likely contributed to the expansion of conotoxin gene numbers. Interestingly, our study also provided evidence of introgression among Conus species, indicating that interspecies hybridization may have played a role in shaping the evolution of diverse conotoxin genes.

CONCLUSIONS

This study highlights the impact of adaptive evolution and introgressive hybridization on the genetic diversity of conotoxin genes and the evolution of Conus. We also propose a hypothesis suggesting that transposable elements might significantly contribute to the remarkable diversity observed in conotoxins. These findings not only enhance our understanding of peptide genetic diversity but also present a novel approach for peptide bioengineering.

Synthesis and insecticidal activity of cysteine-free conopeptides from Conus betulinus

The cone snail Conus betulinus is a vermivorous species that is widely distributed in the South China Sea. Its crude venom contains various peptides used to prey on marine worms. In previous studies, a systematic analysis of the peptide toxin sequences from C. betulinus was carried out using a multiomics technique. In this study, 10 cysteine-free peptides that may possess insecticidal activity were selected from a previously constructed conopeptide library of C. betulinus using the CPY-Fe conopeptide as a template. These conopeptides were prepared by solid-phase peptide synthesis (SPPS), then characterized by the reverse-phase high performance liquid chromatography (HPLC) and mass spectrometry. Insect cytotoxicity and injection experiments revealed that these cysteine-free peptides exerted favorable insecticidal effects, and two of them (Bt010 and Bt016) exhibited high insecticidal efficacy with LD50 of 9.07 nM and 10.93 nM, respectively. In addition, the 3D structures of these peptides were predicted by homology modeling, and a phylogenetic tree was constructed based on the nucleotide data of conopeptides to analyze the relationships among structures, functions, and evolution. A preliminary mechanism for the insecticidal activity of the cysteine-free conopeptides was predicted by molecular docking. To the best of our knowledge, this is the first study to report the insecticidal activity of cysteine-free conopeptides derived from Conus betulinus, signaling that they could potentially be developed into bioinsecticides with desirable properties such as easy preparation, low cost, and high potency.

O1-conotoxin Tx6.7 cloned from the genomic DNA of Conus textile that inhibits calcium currents

Background

Conotoxins exhibit great potential as neuropharmacology tools and therapeutic candidates due to their high affinity and specificity for ion channels, neurotransmitter receptors or transporters. The traditional methods to discover new conotoxins are peptide purification from the crude venom or gene amplification from the venom duct.

Methods

In this study, a novel O1 superfamily conotoxin Tx6.7 was directly cloned from the genomic DNA of Conus textile using primers corresponding to the conserved intronic sequence and 3' UTR elements. The mature peptide of Tx6.7 (DCHERWDWCPASLLGVIYCCEGLICFIAFCI) was synthesized by solid-phase chemical synthesis and confirmed by mass spectrometry.

Results

Patch clamp experiments on rat DRG neurons showed that Tx6.7 inhibited peak calcium currents by 59.29 ± 2.34% and peak potassium currents by 22.33 ± 7.81%. In addition, patch clamp on the ion channel subtypes showed that 10 μM Tx6.7 inhibited 56.61 ± 3.20% of the hCa_V1.2 currents, 24.67 ± 0.91% of the hCa_V2.2 currents and 7.30 ± 3.38% of the hNa_V1.8 currents. Tx6.7 had no significant toxicity to ND7/23 cells and increased the pain threshold from 0.5 to 4 hours in the mouse hot plate assay.

Conclusion

Our results suggested that direct cloning of conotoxin sequences from the genomic DNA of cone snails would be an alternative approach to obtaining novel conotoxins. Tx6.7 could be used as a probe tool for ion channel research or a therapeutic candidate for novel drug development.

Native and Engineered Cyclic Disulfide-Rich Peptides as Drug Leads

Bioactive peptides are a highly abundant and diverse group of molecules that exhibit a wide range of structural and functional variation. Despite their immense therapeutic potential, bioactive peptides have been traditionally perceived as poor drug candidates, largely due to intrinsic shortcomings that reflect their endogenous heritage, i.e., short biological half-lives and poor cell permeability. In this review, we examine the utility of molecular engineering to insert bioactive sequences into constrained scaffolds with desired pharmaceutical properties. Applying lessons learnt from nature, we focus on molecular grafting of cyclic disulfide-rich scaffolds (naturally derived or engineered), shown to be intrinsically stable and amenable to sequence modifications, and their utility as privileged frameworks in drug design.

Historical Perspective of the Characterization of Conotoxins Targeting Voltage-Gated Sodium Channels

Marine toxins have potent actions on diverse sodium ion channels regulated by transmembrane voltage (voltage-gated ion channels) or by neurotransmitters (nicotinic acetylcholine receptor channels). Studies of these toxins have focused on varied aspects of venom peptides ranging from evolutionary relationships of predator and prey, biological actions on excitable tissues, potential application as pharmacological intervention in disease therapy, and as part of multiple experimental approaches towards an understanding of the atomistic characterization of ion channel structure. This review examines the historical perspective of the study of conotoxin peptides active on sodium channels gated by transmembrane voltage, which has led to recent advances in ion channel research made possible with the exploitation of the diversity of these marine toxins.

Exploring the Limits of Cyanobactin Macrocyclase PatGmac: Cyclization of PawS-Derived Peptide Sunflower Trypsin Inhibitor-1 and Cyclotide Kalata B1

The subtilisin-like macrocyclase PatGmac is produced by the marine cyanobacterium Prochloron didemni. This enzyme is involved in the last step of the biosynthesis of patellamides, a cyanobactin type of ribosomally expressed and post-translationally modified cyclic peptides. PatGmac recognizes, cleaves, and cyclizes precursor peptides after a specific recognition motif comprised of a C-terminal tail with the sequence motif -AYDG. The result is the native macrocyclic patellamide, which has eight amino acid residues. Macrocyclase activity can be exploited by incorporating that motif in other short linear peptide precursors, which then are formed into head-to-tail cyclized peptides. Here, we explore the possibility of using PatGmac in the cyclization of peptides larger than the patellamides, namely, the PawS-derived peptide sunflower trypsin inhibitor-1 (SFTI-1) and the cyclotide kalata B1. These peptides fall under two distinct families of disulfide constrained macrocyclic plant peptides. They are both implicated as scaffolds for drug design due to their structures and unusual stability. We show that PatGmac can be used to efficiently cyclize the 14 amino acid residue long SFTI-1, but less so the 29 amino acid residue long kalata B1.

What We Have Gained from Ibogaine: α3β4 Nicotinic Acetylcholine Receptor Inhibitors as Treatments for Substance Use Disorders

For decades, ibogaine─the main psychoactive alkaloid found in Tabernanthe iboga─has been investigated as a possible treatment for substance use disorders (SUDs) due to its purported ability to interrupt the addictive properties of multiple drugs of abuse. Of the numerous pharmacological actions of ibogaine and its derivatives, the inhibition of α3β4 nicotinic acetylcholine receptors (nAChRs), represents a probable mechanism of action for their apparent anti-addictive activity. In this Perspective, we examine several classes of compounds that have been discovered and developed to target α3β4 nAChRs. Specifically, by focusing on compounds that have proven efficacious in pre-clinical models of drug abuse and have been evaluated clinically, we highlight the promising potential of the α3β4 nAChRs as viable targets to treat a wide array of SUDs. Additionally, we discuss the challenges faced by the existing classes of α3β4 nAChR ligands that must be overcome to develop them into therapeutic treatments.

Proteomic Analysis of the Predatory Venom of Conus striatus Reveals Novel and Population-Specific κA-Conotoxin SIVC

Animal venoms are a rich source of pharmacological compounds with ecological and evolutionary significance, as well as with therapeutic and biotechnological potentials. Among the most promising venomous animals, cone snails produce potent neurotoxic venom to facilitate prey capture and defend against aggressors. Conus striatus, one of the largest piscivorous species, is widely distributed, from east African coasts to remote Polynesian Islands. In this study, we investigated potential intraspecific differences in venom composition between distinct geographical populations from Mayotte Island (Indian Ocean) and Australia (Pacific Ocean). Significant variations were noted among the most abundant components, namely the κA-conotoxins, which contain three disulfide bridges and complex glycosylations. The amino acid sequence of a novel κA-conotoxin SIVC, including its N-terminal acetylated variant, was deciphered using tandem mass spectrometry (MS/MS). In addition, the glycosylation pattern was found to be consisting of two HexNAc and four Hex for the Mayotte population, which diverge from the previously characterized two HexNAc and three Hex combinations for this species, collected elsewhere. Whereas the biological and ecological roles of these modifications remain to be investigated, population-specific glycosylation patterns provide, for the first time, a new level of intraspecific variations in cone snail venoms.

High-Throughput Prediction and Design of Novel Conopeptides for Biomedical Research and Development

Cone snail venoms have been considered a valuable treasure for international scientists and businessmen, mainly due to their pharmacological applications in development of marine drugs for treatment of various human diseases. To date, around 800 Conus species are recorded, and each of them produces over 1,000 venom peptides (termed as conopeptides or conotoxins). This reflects the high diversity and complexity of cone snails, although most of their venoms are still uncharacterized. Advanced multiomics (such as genomics, transcriptomics, and proteomics) approaches have been recently developed to mine diverse Conus venom samples, with the main aim to predict and identify potentially interesting conopeptides in an efficient way. Some bioinformatics techniques have been applied to predict and design novel conopeptide sequences, related targets, and their binding modes. This review provides an overview of current knowledge on the high diversity of conopeptides and multiomics advances in high-throughput prediction of novel conopeptide sequences, as well as molecular modeling and design of potential drugs based on the predicted or validated interactions between these toxins and their molecular targets.

Programmed Aptamer Screening, Characterization, and Rapid Detection for α-Conotoxin MI

Conotoxins (CTXs) are a variety of mixed polypeptide toxins, among which α-conotoxin MI (CTX-MI) is the most toxic. Serious toxic symptoms, a lack of counteracting drugs, and cumbersome detection processes have made CTX-MI a hidden danger for humans. One of the obstacles to resolving this problem is the absence of specific recognition elements. Aptamers have shown great advantages in the fields of molecule detection, drug development, etc. In this study, we screened and characterized aptamers for CTX-MI through a programmed process. MBMI-01c, the isolated aptamer, showed great affinity, with an affinity constant (K_D) of 0.524 μM, and it formed an antiparallel G-quadruplet (GQ) structure for the specific recognition of CTX-MI. Additionally, an aptasensor based on the biolayer interferometry (BLI) platform was developed and displayed high precision, specificity, and repeatability with a limit of detection (LOD) of 0.26 μM. This aptasensor provides a potential tool for the rapid detection of CTX-MI in 10 min. The aptamer can be further developed for the enrichment, detoxification, and biological studies of CTX-MI. Additionally, the programmed process is applicable to screening and characterizing aptamers for other CTXs.

Anti-Ovarian Cancer Conotoxins Identified from Conus Venom

Conotoxins constitute a treasury of drug resources and have attracted widespread attention. In order to explore biological candidates from the marine cone snail, we isolated and identified three novel conopeptides named as Vi14b, Vi002, Vi003, three conotoxin variants named as Mr3d.1, Mr3e.1, Tx3a.1, and three known conotoxins (Vi15a, Mr3.8 and TCP) from crude venoms of Conus virgo, Conus marmoreus and Conus texile. Mr3.8 (I-V, II-VI, III-IV) and Tx3a.1 (I-III, II-VI, IV-V) both showed a novel pattern of disulfide connectivity, different from that previously established for the µ- and ψ-conotoxins. Concerning the effect on voltage-gated sodium channels, Mr3e.1, Mr3.8, Tx3a.1, TCP inhibited Na_v1.4 or Na_v1.8 by 21.51~24.32% of currents at semi-activated state (TP2) at 10 μmol/L. Certain anti-ovarian cancer effects on ID-8 cells were exhibited by Tx3a.1, Mr3e.1 and Vi14b with IC₅₀ values of 24.29 µM, 54.97 µM and 111.6 µM, respectively. This work highlights the role of conotoxin libraries in subsequent drug discovery for ovarian cancer treatment.

The T-1 conotoxin μ-SrVA from the worm hunting marine snail Conus spurius preferentially blocks the human NaV1.5 channel

Conotoxin sr5a had previously been identified in the vermivorous cone snail Conus spurius. This conotoxin is a highly hydrophobic peptide, with the sequence IINWCCLIFYQCC, which has a cysteine pattern "CC-CC" belonging to the T-1 superfamily. It is well known that this superfamily binds to molecular targets such as calcium channels, G protein-coupled receptors (GPCR), and neuronal nicotinic acetylcholine receptors (nAChR) and exerts an effect mainly in the central nervous system. However, its effects on other molecular targets are not yet defined, suggesting the potential of newly relevant molecular interactions. To find and demonstrate a potential molecular target for conotoxin sr5a electrophysiological assays were performed on three subtypes of voltage-activated sodium channels (Na_V1.5, Na_V1.6, and Na_V1.7) expressed in HEK-293 cells with three different concentrations of sr5a(200, 400, and 600 nM). 200 nM sr5a blocked currents mediated by Na_V1.5 by 33%, Na_V1.6 by 14%, and Na_V1.7 by 7%. The current-voltage (I-V) relationships revealed that conotoxin sr5a exhibits a preferential activity on the Na_V1.5 subtype; the activation of Na_V1.5 conductance was not modified by the blocking effect of sr5a, but sr5a affected the voltage-dependence of inactivation of channels. Since peptide sr5a showed a specific activity for a sodium channel subtype, we can assign a pharmacological family and rename it as conotoxin µ-SrVA.

Mass Spectrometry Approaches Empowering Neuropeptide Discovery and Therapeutics

The discovery of insulin in the early 1900s ushered in the era of research related to peptides acting as hormones and neuromodulators, among other regulatory roles. These essential gene products are found in all organisms, from the most primitive to the most evolved, and carry important biologic information that coordinates complex physiology and behavior; their misregulation has been implicated in a variety of diseases. The evolutionary origins of at least 30 neuropeptide signaling systems have been traced to the common ancestor of protostomes and deuterostomes. With the use of relevant animal models and modern technologies, we can gain mechanistic insight into orthologous and paralogous endogenous peptides and translate that knowledge into medically relevant insights and new treatments. Groundbreaking advances in medicine and basic science influence how signaling peptides are defined today. The precise mechanistic pathways for over 100 endogenous peptides in mammals are now known and have laid the foundation for multiple drug development pipelines. Peptide biologics have become valuable drugs due to their unique specificity and biologic activity, lack of toxic metabolites, and minimal undesirable interactions. This review outlines modern technologies that enable neuropeptide discovery and characterization, and highlights lessons from nature made possible by neuropeptide research in relevant animal models that is being adopted by the pharmaceutical industry. We conclude with a brief overview of approaches/strategies for effective development of peptides as drugs. SIGNIFICANCE STATEMENT: Neuropeptides, an important class of cell-cell signaling molecules, are involved in maintaining a range of physiological functions. Since the discovery of insulin's activity, over 100 bioactive peptides and peptide analogs have been used as therapeutics. Because these are complex molecules not easily predicted from a genome and their activity can change with subtle chemical modifications, mass spectrometry (MS) has significantly empowered peptide discovery and characterization. This review highlights contributions of MS-based research towards the development of therapeutic peptides.

Pathophysiological Responses to Conotoxin Modulation of Voltage-Gated Ion Currents

Voltage-gated ion channels are plasma membrane proteins that generate electrical signals following a change in the membrane voltage. Since they are involved in several physiological processes, their dysfunction may be responsible for a series of diseases and pain states particularly related to neuronal and muscular systems. It is well established for decades that bioactive peptides isolated from venoms of marine mollusks belonging to the Conus genus, collectively known as conotoxins, can target different types and isoforms of these channels exerting therapeutic effects and pain relief. For this reason, conotoxins are widely used for either therapeutic purposes or studies on ion channel mechanisms of action disclosure. In addition their positive property, however, conotoxins may generate pathological states through similar ion channel modulation. In this narrative review, we provide pieces of evidence on the pathophysiological impacts that different members of conotoxin families exert by targeting the three most important voltage-gated channels, such as sodium, calcium, and potassium, involved in cellular processes.

Peptide Toxins as Biothreats and the Potential for AI Systems to Enhance Biosecurity

Biological weapons have been used for thousands of years, but recent advances in synthesis technologies have made peptide and protein toxin production more accessible and pose a threat to biosecurity worldwide. Natural toxins such as conotoxins, certain hemolytic compounds, and enterotoxins are peptide agents that can be synthesized in an environment with weak biosecurity measures and rudimentarily weaponized for limited use against smaller targets for lethal or nonlethal effects. Technological advances are changing the threat landscape around biological weapons and potentially facilitating a shift from state sponsored to more micro-level threats stemming from terror cells, insider threats, and lone wolf attacks. Here, we present the reader with an overview of the threat of peptide and protein toxins, provide examples of potent peptide toxins, and introduce capabilities of a proposed biosecurity program utilizing artificial intelligence that unifies commercial nucleotide and peptide synthesis vendors.

Detection of αB-Conotoxin VxXXIVA (αB-CTX) by ic-ELISA Based on an Epitope-Specific Monoclonal Antibody

In view of the toxicological hazard and important applications in analgesics and cancer chemotherapeutics of αB-CTX, it is urgent to develop an accurate, effective and feasible immunoassay for the determination and analysis of αB-CTX in real samples. In this study, MBP-αB-CTX4 tandem fusion protein was used as an immunogen to elicit a strong immune response, and a hybridoma cell 5E4 secreting IgG2b against αB-CTX was successfully screened by hybridoma technology. The affinity of the purified 5E4 monoclonal antibody (mAb) was 1.02 × 108 L/mol, which showed high affinity and specificity to αB-CTX. Epitope 1 of αB-CTX is the major binding region for 5E4 mAb recongnization, and two amino acid residues (14L and 15F) in αB-CTX were critical sites for the interaction between αB-CTX and 5E4 mAb. Indirect competitive ELISA (ic-ELISA) based on 5E4 mAb was developed to detect and analyze αB-CTX in real samples, and the linear range of ic-ELISA to αB-CTX was 117–3798 ng/mL, with a limit of detection (LOD) of 81 ng/mL. All the above results indicated that the developed ic-ELISA had high accuracy and repeatability, and it could be applied for αB-CTX detection and drug analysis in real samples.

A Novel α4/7-Conotoxin QuIA Selectively Inhibits α3β2 and α6/α3β4 Nicotinic Acetylcholine Receptor Subtypes with High Efficacy

α6β4 nAChR is expressed in the peripheral and central nervous systems and is associated with pain, addiction, and movement disorders. Natural α-conotoxins (α-CTxs) can effectively block different nAChR subtypes with higher efficacy and selectivity. However, the research on α6β4 nAChR is relatively poor, partly because of the lack of available target-specific α-CTxs. In this study, we synthesized a novel α-4/7 conotoxin QuIA that was found from Conus quercinus. We investigated the efficacy of this peptide to different nAChR subtypes using a two-electrode voltage-clamp technique. Remarkably, we found α-QuIA inhibited the neuronal α3β2 and α6/α3β4 nAChR subtypes with significantly high affinity (IC₅₀ was 55.7 nM and 90.68 nM, respectively), and did not block other nAChR subtypes even at a high concentration of 10 μM. In contrast, most α-CTxs have been determined so far to effectively block the α6/α3β4 nAChR subtype while also maintaining a similar higher efficacy against the closely related α6β2β3 and/or α3β4 subtypes, which are different from QuIA. In conclusion, α-QuIA is a novel α4/7-CTx, which has the potential to develop as an effective neuropharmacology tool to detect the function of α6β4 nAChR.

Biomedical Potential of the Neglected Molluscivorous and Vermivorous Conus Species

Within the Conidae family, the piscivorous Conus species have been a hotspot target for drug discovery. Here, we assess the relevance of Conus and their other feeding habits, and thus under distinctive evolutionary constraints, to highlight the potential of neglected molluscivorous and vermivorous species in biomedical research and pharmaceutical industry. By singling out the areas with inadequate Conus disquisition, such as the Tamil Nadu Coast and the Andaman Islands, research resources can be expanded and better protected through awareness. In this study, 728 Conus species and 190 species from three other genera (1 from Californiconus, 159 from Conasprella and 30 from Profundiconus) in the Conidae family are assessed. The phylogenetic relationships of the Conidae species are determined and their known feeding habits superimposed. The worm-hunting species appeared first, and later the mollusc- and fish-hunting species were derived independently in the Neogene period (around 23 million years ago). Interestingly, many Conus species in the warm and shallow waters become polyphagous, allowing them to hunt both fish and worms, given the opportunities. Such newly gained trait is multi originated. This is controversial, given the traditional idea that most Conus species are specialized to hunt certain prey categories. However, it shows the functional complexity and great potential of conopeptides from some worm-eating species. Pharmaceutical attempts and relevant omics data have been differentially obtained. Indeed, data from the fish-hunting species receive strong preference over the worm-hunting ones. Expectedly, conopeptides from the fish-hunting species are believed to include the most potential candidates for biomedical research. Our work revisits major findings throughout the Conus evolution and emphasizes the importance of increasing omics surveys complemented with further behavior observation studies. Hence, we claim that Conus species and their feeding habits are equally important, highlighting many places left for Conus exploration worldwide. We also discuss the Conotoxin drug discovery potentials and the urgency of protecting the bioresources of Conus species. In particular, some vermivorous species have demonstrated great potential in malaria therapy, while other conotoxins from several worm- and mollusc-eating species exhibited explicit correlation with SARS-CoV-2. Reclaiming idle data with new perspectives could also promote interdisciplinary studies in both virological and toxicological fields.

Preparation and Functional Identification of a Novel Conotoxin QcMNCL-XIII0.1 from Conus quercinus

Conotoxins are tools used by marine Conus snails to hunt and are a significant repository for marine drug research. Conotoxins highly selectively coordinate different subtypes of various ion channels, and a few have been used in pain management. Although more than 8000 conotoxin genes have been found, the biological activity and function of most have not yet been examined. In this report, we selected the toxin gene QcMNCL-XIII0.1 from our previous investigation and studied it in vitro. First, we successfully prepared active recombinant QcMNCL-XIII0.1 using a TrxA (Thioredoxin A)-assisted folding expression vector based on genetic engineering technology. Animal experiments showed that the recombinant QcMNCL-XIII0.1 exhibited nerve conduction inhibition similar to that of pethidine hydrochloride. With flow cytometry combined fluorescent probe Fluo-4 AM, we found that 10 ng/μL recombinant QcMNCL-XIII0.1 inhibited the fluorescence intensity by 31.07% in the 293T cell model transfected with Cav3.1, implying an interaction between α1G T-type calcium channel protein and recombinant QcMNCL-XIII0.1. This toxin could be an important drug in biomedical research and medicine for pain control.

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.

Tetramine in the Salivary Glands of Marine Carnivorous Snails: Analysis, Distribution, and Toxicological Aspects

Focusing on tetramine, tetramethylammonium ion, contained in the salivary glands of marine carnivorous snails, this paper gives an overview of analytical methods, distribution in marine snails, and toxicological aspects. Some Neptunea snails have often caused food poisoning in North Atlantic and Northeast Asia regions, especially in Japan. The toxin of both N. arthritica and N. antiqua was first proven to be tetramine in 1960. Subsequent research on marine snail tetramine has progressed with the development of analytical methods. Of the various methods developed, the LC/ESI-MS method is most recommended for tetramine analysis in terms of sensitivity, specificity, and versatility. Accumulated data show that tetramine is ubiquitously contained at high concentrations (usually several mg/g) in the salivary glands of Neptunea snails. Tetramine is also found in the muscle and viscera of Neptunea snails and even in the salivary gland of marine snails other than Neptunea species, although mostly at low levels (below 0.1 mg/g). Interestingly, the major toxin in the salivary glands of Fusitriton oregonensis and Hemifusus tuba is distinguishable from tetramine. In tetramine poisoning, diverse symptoms attributable to the ganglion-blocking action of tetramine, such as visual disturbance, headache, dizziness, abdominal pain, and nausea, develop within 30 min after ingestion of snails because of rapid absorption of tetramine from the gastrointestinal tract. The symptoms are generally mild and subside in a short time (within 24 at most) because of rapid excretion through the kidney. However, it should be kept in mind that tetramine poisoning can be severe in patients with kidney dysfunction, as shown by two recent case reports. Finally, given the diffusion of tetramine from the salivary gland to the muscle during boiling and thawing of snails, removal of salivary glands from live snails is essential to avoid tetramine poisoning.

Exposing structural variations in SARS-CoV-2 evolution

The mutation of SARS-CoV-2 influences viral function as residue replacements affect both physiochemical properties and folding conformations. Although a large amount of data on SARS-CoV-2 is available, the investigation of how viral functions change in response to mutations is hampered by a lack of effective structural analysis. Here, we exploit the advances of protein structure fingerprint technology to study the folding conformational changes induced by mutations. With integration of both protein sequences and folding conformations, the structures are aligned for SARS-CoV to SARS-CoV-2, including Alpha variant (lineage B.1.1.7) and Delta variant (lineage B.1.617.2). The results showed that the virus evolution with change in mutational positions and physicochemical properties increased the affinity between spike protein and ACE2, which plays a critical role in coronavirus entry into human cells. Additionally, these structural variations impact vaccine effectiveness and drug function over the course of SARS-CoV-2 evolution. The analysis of structural variations revealed how the coronavirus has gradually evolved in both structure and function and how the SARS-CoV-2 variants have contributed to more severe acute disease worldwide.

Conformational dynamics in peptide toxins: Implications for receptor interactions and molecular design

Peptide toxins are potent and often exquisitely selective probes of the structure and function of ion channels and receptors, and are therefore of significant interest to the pharmaceutical and biotech industries as both pharmacological tools and therapeutic leads. The three-dimensional structures of peptide toxins are essential as a basis for understanding their structure-activity relationships and their binding to target receptors, as well as in guiding the design of analogues with modified potency and/or selectivity for key targets. NMR spectroscopy has played a key role in elucidating the structures of peptide toxins and probing their structure-function relationships. In this article, we highlight the additional important contribution of NMR to characterising the dynamics of peptide toxins. We also compare the information available from NMR measurements with that afforded by molecular dynamics simulations. We describe several examples of the importance of dynamics measurements over a range of timescales for understanding the structure-function relationships of peptide toxins and their receptor engagement. Peptide toxins that inhibit the voltage-gated potassium channel K_V1.3 with pM affinities display different degrees of conformational flexibility, even though they contain multiple disulfide bonds, and this flexibility can affect the relative orientation of residues that have been shown to be critical for channel binding. Information on the dynamic properties of peptide toxins is important in the design of analogues or mimetics where receptor-bound structures are not available.

Voltage-Gated Sodium Channels: A Prominent Target of Marine Toxins

Voltage-gated sodium channels (VGSCs) are considered to be one of the most important ion channels given their remarkable physiological role. VGSCs constitute a family of large transmembrane proteins that allow transmission, generation, and propagation of action potentials. This occurs by conducting Na⁺ ions through the membrane, supporting cell excitability and communication signals in various systems. As a result, a wide range of coordination and physiological functions, from locomotion to cognition, can be accomplished. Drugs that target and alter the molecular mechanism of VGSCs’ function have highly contributed to the discovery and perception of the function and the structure of this channel. Among those drugs are various marine toxins produced by harmful microorganisms or venomous animals. These toxins have played a key role in understanding the mode of action of VGSCs and in mapping their various allosteric binding sites. Furthermore, marine toxins appear to be an emerging source of therapeutic tools that can relieve pain or treat VGSC-related human channelopathies. Several studies documented the effect of marine toxins on VGSCs as well as their pharmaceutical applications, but none of them underlined the principal marine toxins and their effect on VGSCs. Therefore, this review aims to highlight the neurotoxins produced by marine animals such as pufferfish, shellfish, sea anemone, and cone snail that are active on VGSCs and discuss their pharmaceutical values.

Identification of Novel Conotoxin Precursors from the Cone Snail Conus spurius by High-Throughput RNA Sequencing

Marine gastropods of the genus Conus, comprising more than 800 species, have the characteristic of injecting worms and other prey with venom. These conopeptide toxins, highly diverse in structure and action, are highly potent and specific for their molecular targets (ion channels, receptors, and transporters of the prey's nervous system), and thus are important research tools and source for drug discovery. Next-generation sequencing technologies are speeding up the discovery of novel conopeptides in many of these species, but only limited information is available for Conus spurius, which inhabits sandy mud. To search for new precursor conopeptides, we analyzed the transcriptome of the venous ducts of C. spurius and identified 55 putative conotoxins. Seven were selected for further study and confirmed by Sanger sequencing to belong to the M-superfamily (Sr3.M01 and Sr3.M02), A-superfamily (Sr1.A01 and Sr1.A02), O-superfamily (Sr15.O01), and Con-ikot-ikot (Sr21.CII01 and Sr22.CII02). Six of these have never been reported. To our knowledge, this report is the first to use high-throughput RNA sequencing for the study of the diversity of C. spurius conotoxins.

Venom peptides - A comprehensive translational perspective in pain management

Venom peptides have been evolving complex therapeutic interventions that potently and selectively modulate a range of targets such as ion channels, receptors, and signaling pathways of physiological processes making it potential therapeutic. Several venom peptides were deduced in vivo for clinical development targeting pain management, diabetes, cardiovascular diseases, antimicrobial activity. Several contributions have been detailed for a clear perspective for a better understanding of venomous animals, their venom, and their pharmacological effects. Here we unravel and summarize the recent advances in wide venom peptides across varieties of species for their therapeutics prospects.

Bidentatide, a Novel Plant Peptide Derived from Achyranthes bidentata Blume: Isolation, Characterization, and Neuroprotection through Inhibition of NR2B-Containing NMDA Receptors

Increasing attention is being focused on the use of polypeptide-based N-methyl-d-aspartate (NMDA) receptor antagonists for the treatment of nervous system disorders. In our study on Achyranthes bidentata Blume, we identified an NMDA receptor subtype 2B (NR2B) antagonist that exerts distinct neuroprotective actions. This antagonist is a 33 amino acid peptide, named bidentatide, which contains three disulfide bridges that form a cysteine knot motif. We determined the neuroactive potential of bidentatide by evaluating its in vitro effects against NMDA-mediated excitotoxicity. The results showed that pretreating primary cultured hippocampal neurons with bidentatide prevented NMDA-induced cell death and apoptosis via multiple mechanisms that involved intracellular Ca²⁺ inhibition, NMDA current inhibition, and apoptosis-related protein expression regulation. These mechanisms were all dependent on bidentatide-induced inhibitory regulation of NR2B-containing NMDA receptors; thus, bidentatide may contribute to the development of neuroprotective agents that would likely possess the high selectivity and safety profiles inherent in peptide drugs.

Improved prediction of conopeptide superfamilies with ConoDictor 2.0

Motivation

Cone snails are among the richest sources of natural peptides with promising pharmacological and therapeutic applications. With the reduced costs of RNAseq, scientists now heavily rely on venom gland transcriptomes for the mining of novel bioactive conopeptides, but the bioinformatic analyses often hamper the discovery process.

Results

Here, we present ConoDictor 2.0 as a standalone and user-friendly command-line program. We have updated the program originally published as a web server 10 years ago using novel and updated tools and algorithms and improved our classification models with new and higher quality sequences. ConoDictor 2.0 is now more accurate, faster, multiplatform and able to deal with a whole cone snail venom gland transcriptome (raw reads or contigs) in a very short time. The new version of Conodictor also improves the identification and subsequent classification for entirely novel or relatively distant conopeptides. We conducted various tests on known conopeptides from public databases and on the published venom duct transcriptome of Conus geographus, and compared previous results with the output of ConoDictor 2.0, ConoSorter and BLAST. Overall, ConoDictor 2.0 is 4 to 8 times faster for the analysis of a whole transcriptome on a single core computer and performed better at predicting gene superfamily.

Availability and implementation

ConoDictor 2.0 is available as a python 3 git folder at https://github.com/koualab/conodictor.

Supplementary information

Supplementary data are available at Bioinformatics Advances online.

A novel proline-rich M-superfamily conotoxin that can simultaneously affect sodium, potassium and calcium currents

Background

Conotoxins have become a research hotspot in the neuropharmacology field for their high activity and specificity in targeting ion channels and neurotransmitter receptors. There have been reports of a conotoxin acting on two ion channels, but rare reports of a conotoxin acting on three ion channels.

Methods

Vr3a, a proline-rich M-superfamily conotoxin from a worm-hunting Conus varius, was obtained by solid-phase synthesis and identified by mass spectrometry. The effects of synthesized Vr3a on sodium, potassium and calcium currents were tested on rat DRG cells by patch clamp experiments. The further effects of Vr3a on human Ca_v1.2 and Ca_v2.2 currents were tested on HEK293 cells.

Results

About 10 μM Vr3a has no effects on the peak sodium currents, but can induce a ~10 mV shift in a polarizing direction in the current-voltage relationship. In addition, 10 μM Vr3a can increase 19.61 ± 5.12% of the peak potassium currents and do not induce a shift in the current-voltage relationship. An amount of 10 μM Vr3a can inhibit 31.26% ± 4.53% of the peak calcium currents and do not induce a shift in the current-voltage relationship. The IC₅₀ value of Vr3a on calcium channel currents in rat DRG neurons is 19.28 ± 4.32 μM. Moreover, 10 μM Vr3a can inhibit 15.32% ± 5.41% of the human Ca_v1.2 currents and 12.86% ± 4.93% of the human Ca_v2.2 currents.

Conclusions

Vr3a can simultaneously affect sodium, potassium and calcium currents. This novel triple-target conotoxin Vr3a expands understanding of conotoxin functions.

The complete mitochondrial DNA genome of a cone snail, Conus betulinus (Neogastropoda: Conidae), from the South China sea

The complete mitochondrial genome of the tubular cone snail Conus betulinus is presented in this study. The C. betulinus mitochondrial genome was 16,240 bp with 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a non-coding AT-rich region (D-loop). The overall base composition was estimated to be 25.67% for A, 38.26% for T, 21.38% for G, and 14.69% for C, with a high A + T content of 63.93%. Phylogenetic analyses based on 13 PCGs showed the close relationship of vermivorous C. betulinus with the common ancestor of molluscivorous Conus textile and Conus gloriamaris, providing a basis for further studies on the phylogenetics of cone snails according to their dietary type.

Human health and snails

Snails can provide a considerable variety of bioactive compounds for cosmetic and pharmaceutical industries, useful for the development of new formulations with less toxicity and post effects compared to regular compounds used for the purpose. Compounds from crude extract, mucus, slime consist of glycans, polypeptides, proteins, etc., and can be used for curing diseases like viral lesions, warts, and different dermal problems. Some particular uses of snails involve treating post-traumatic stress. Micro RNA of Lymnaea stagnalis, was known to be responsible for the development of long-term memory and treatment of Alzheimer's and Dementia like diseases. This review explores the application of various bioactive compounds from snails with its potential as new translational medicinal and cosmetic applications. Snail bioactive compounds like ω-MVIIA, μ-SIIIA, μO-MrVIB, Xen2174, δ-EVIA, α-Vc1.1, σ-GVIIA, Conantokin-G, and Contulakin-G, conopeptides can be used for the development of anti-cancer drugs. These compounds target the innate immunity and improve the defense system of humans and provide protection against these life-threatening health concerns.AbbreviationsFDA: Food and Drug Administration; UTI: urinal tract infection; nAChRs: nicotinic acetylcholine receptors; NMDA: N-methyl-D-aspartate; CNS: central nervous system; CAR T: chimeric antigen receptors therapy; Micro RNA: micro ribonucleic acid.

Cytotoxicity Studies of the Crude venom and Fractions of Persian Gulf Snail (Conus textile) on Chronic Lymphocytic Leukemia and Normal Lymphocytes

Background:

Marine animals have been considered by many researchers due to their various pharmacological effects. One group of marine animals that have been studied is cone snails. The conotoxin obtained from these marine animals has various therapeutic effects.

Methods:

This study was designed to investigate the apoptotic effects of crude venom of Conus textile and its fractions (A and B) on chronic lymphocytic leukemia (CLL) cells. Accordingly, parameters such as cell viability, reactive oxygen species (ROS) level, collapse in mitochondrial membrane potential (MMP), lysosomal membrane damage and caspase-3 activation were evaluated.

Results:

The results showed that the crude venom (50, 100 and 200 µg/ml) from Conus textile and its fraction B (50, 100 and 200 µg/ml) significantly reduced viability in CLL B-lymphocyte. In addition, exposure of CLL B-lymphocyte to fraction B (50, 100 and 200 µg/ml) was associated with an increase in the level of ROS, the collapse of the MMP, damage to the lysosomal membrane, and activation of caspase-3.

Conclusion:

According to results, it was concluded that fraction B from crude venom of Conus textile causes selective toxicity on CLL B-lymphocyte with almost no effect on a normal lymphocyte. Furthermore, this venom fraction could be a promising candidate for induction of apoptosis in patients with CLL through the mitochondrial pathway.

Bacillus amyloliquefaciens B10 can alleviate aflatoxin B1-induced kidney oxidative stress and apoptosis in mice

Aflatoxin B1(AFB1) widely exists in food and feed, which seriously endangers human and animal health. How to detoxify AFB1 is a research hotspot at present. This study attempts to use the Bacillus amyloliquefaciens B10, one of probiotics strain as the research object to ascertain whether it can alleviate the kidney injury induced by AFB1 in mice and its mechanism. Fifty-six mice were divided into four groups (control, AFB1, AFB1 + B10, and B10). The mice that received intragastric administration for 28 days were euthanised, and serum was collected for biochemical index detection with fresh kidney tissue taken for HE staining, TUNEL detection, and protein expression detection. Our results showed that the biochemical indices changed, significant pathological changes appeared, the number of apoptotic cells increased in the kidney tissue of the AFB1 group mice; the protein expressions of Nrf2, HO-1,AKT, P-AKT, and Bcl-2 in the AFB1 group were significantly decreased; the protein expressions of Keap-1, PTEN, Bax, Caspase-9, and Caspase-3 were significantly increased. After B. amyloliquefaciens B10 co-treatment, compared with the AFB1 group, the biochemical indices, pathological changes, and protein expressions were significantly reversed. The results indicated that B. amyloliquefaciens B10 can alleviate AFB1-induced kidney injury in mice.

Combined Proteotranscriptomic-Based Strategy to Discover Novel Antimicrobial Peptides from Cone Snails

Despite their impressive diversity and already broad therapeutic applications, cone snail venoms have received less attention as a natural source in the investigation of antimicrobial peptides than other venomous animals such as scorpions, spiders, or snakes. Cone snails are among the largest genera (Conus sp.) of marine invertebrates, with more than seven hundred species described to date. These predatory mollusks use their sophisticated venom apparatus to capture prey or defend themselves. In-depth studies of these venoms have unraveled many biologically active peptides with pharmacological properties of interest in the field of pain management, the treatment of epilepsy, neurodegenerative diseases, and cardiac ischemia. Considering sequencing efficiency and affordability, cone snail venom gland transcriptome analyses could allow the discovery of new, promising antimicrobial peptides. We first present here the need for novel compounds like antimicrobial peptides as a viable alternative to conventional antibiotics. Secondly, we review the current knowledge on cone snails as a source of antimicrobial peptides. Then, we present the current state of the art in analytical methods applied to crude or milked venom followed by how antibacterial activity assay can be implemented for fostering cone snail antimicrobial peptides studies. We also propose a new innovative profile Hidden Markov model-based approach to annotate full venom gland transcriptomes and speed up the discovery of potentially active peptides from cone snails.

Brevetoxin and Conotoxin Interactions with Single-Domain Voltage-Gated Sodium Channels from a Diatom and Coccolithophore

The recently characterized single-domain voltage-gated ion channels from eukaryotic protists (EukCats) provide an array of novel channel proteins upon which to test the pharmacology of both clinically and environmentally relevant marine toxins. Here, we examined the effects of the hydrophilic µ-CTx PIIIA and the lipophilic brevetoxins PbTx-2 and PbTx-3 on heterologously expressed EukCat ion channels from a marine diatom and coccolithophore. Surprisingly, none of the toxins inhibited the peak currents evoked by the two EukCats tested. The lack of homology in the outer pore elements of the channel may disrupt the binding of µ-CTx PIIIA, while major structural differences between mammalian sodium channels and the C-terminal domains of the EukCats may diminish interactions with the brevetoxins. However, all three toxins produced significant negative shifts in the voltage dependence of activation and steady state inactivation, suggesting alternative and state-dependent binding conformations that potentially lead to changes in the excitability of the phytoplankton themselves.

Small-molecule mimicry hunting strategy in the imperial cone snail, Conus imperialis

Venomous animals hunt using bioactive peptides, but relatively little is known about venom small molecules and the resulting complex hunting behaviors. Here, we explored the specialized metabolites from the venom of the worm-hunting cone snail, Conus imperialis Using the model polychaete worm Platynereis dumerilii, we demonstrate that C. imperialis venom contains small molecules that mimic natural polychaete mating pheromones, evoking the mating phenotype in worms. The specialized metabolites from different cone snails are species-specific and structurally diverse, suggesting that the cones may adopt many different prey-hunting strategies enabled by small molecules. Predators sometimes attract prey using the prey's own pheromones, in a strategy known as aggressive mimicry. Instead, C. imperialis uses metabolically stable mimics of those pheromones, indicating that, in biological mimicry, even the molecules themselves may be disguised, providing a twist on fake news in chemical ecology.