ORCID Profile
0000-0001-7454-6522
Current Organisation
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Medicinal and Biomolecular Chemistry | Proteins and Peptides | Biologically Active Molecules | Biological And Medical Chemistry | Characterisation of Biological Macromolecules | Biochemistry and Cell Biology | Organic Chemical Synthesis | Synthesis Of Macromolecules | Plant Protection (Pests, Diseases And Weeds) | Basic Pharmacology | Animal Protection (Pests And Pathogens) | Basic Pharmacology | Membrane Biology | Macromolecular and Materials Chemistry | Biologically active molecules | Proteins and peptides | Nanochemistry and Supramolecular Chemistry | Characterisation Of Macromolecules | Chemical Characterisation of Materials | Medicinal and biomolecular chemistry | Structural Biology (incl. Macromolecular Modelling) | Molecular Evolution | Medical Biochemistry: Proteins And Peptides | Analytical Biochemistry | Cell Metabolism | Protein Targeting And Signal Transduction | Enzymes | Food Processing | Other Food Sciences | Organic Chemistry | Cheminformatics and Quantitative Structure-Activity Relationships | Animal Production | Biotechnology Not Elsewhere Classified | Food Sciences | Proteomics and Intermolecular Interactions (excl. Medical Proteomics) | Gene Expression | Medical Biochemistry: Proteins and Peptides (incl. Medical Proteomics) | Bioinformatics
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Biological sciences | Expanding Knowledge in the Biological Sciences | Treatments (e.g. chemicals, antibiotics) | Chemical sciences | Nervous system and disorders | Expanding Knowledge in the Medical and Health Sciences | Field crops | Nervous System and Disorders | Livestock | Prevention—biologicals (e.g. vaccines) | Diagnostics | Infectious diseases | Cardiovascular system and diseases | Control of pests and exotic species | Cancer and related disorders | Disease distribution and transmission | Expanding Knowledge in the Agricultural and Veterinary Sciences | Dairy products |
Related Links
Publications
Electrospray liquid chromatography/mass spectrometry fingerprinting of Acanthophis (death adder) venoms: Taxonomic and toxinological implications
Publisher: Wiley
Date: 07-02-2002
DOI: 10.1002/RCM.613
Abstract: Death adders (genus Acanthophis) are unique among elapid snakes in both morphology and venom composition. Despite this genus being among the most ergent of all elapids, the venom has been historically regarded as relatively quite simple. In this study, liquid chromatography/mass spectrometry (LC/MS) analysis has revealed a much greater ersity in venom composition, including the presence of molecules of novel molecular weights that may represent a new class of venom component. Furthermore, significant variation exists between species and populations, which allow for the LC/MS fingerprinting of each species. Mass profiling of Acanthophis venoms clearly demonstrates the effectiveness of this technique which underpins fundamental studies ranging from chemotaxonomy to drug design.
Novel ω-conotoxins from Conus catus discriminate among neuronal calcium channel subtypes
Publisher: Elsevier BV
Date: 11-2000
Three-dimensional solution structure of μ-conotoxin GIIIB, a specific blocker of skeletal muscle sodium channels
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/BI960073O
Evolution of separate predation-and defence-evoked venoms in carnivorous cone snails
Publisher: Springer Science and Business Media LLC
Date: 24-03-2014
DOI: 10.1038/NCOMMS4521
Multiple actions of f-LITX-Lw1a on ryanodine receptors reveal a functional link between scorpion DDH and ICK toxins
Publisher: Proceedings of the National Academy of Sciences
Date: 13-05-2013
Abstract: We recently reported the isolation of a scorpion toxin named U 1 -liotoxin-Lw1a (U 1 -LITX-Lw1a) that adopts an unusual 3D fold termed the disulfide-directed hairpin (DDH) motif, which is the proposed evolutionary structural precursor of the three-disulfide-containing inhibitor cystine knot (ICK) motif found widely in animals and plants. Here we reveal that U 1 -LITX-Lw1a targets and activates the mammalian ryanodine receptor intracellular calcium release channel (RyR) with high (fM) potency and provides a functional link between DDH and ICK scorpion toxins. Moreover, U 1 -LITX-Lw1a, now described as φ-liotoxin-Lw1a (φ-LITX-Lw1a), has a similar mode of action on RyRs as scorpion calcines, although with significantly greater potency, inducing full channel openings at lower (fM) toxin concentrations whereas at higher pM concentrations increasing the frequency and duration of channel openings to a submaximal state. In addition, we show that the C-terminal residue of φ-LITX-Lw1a is crucial for the increase in full receptor openings but not for the increase in receptor subconductance opening, thereby supporting the two-binding-site hypothesis of scorpion toxins on RyRs. φ-LITX-Lw1a has potential both as a pharmacological tool and as a lead molecule for the treatment of human diseases that involve RyRs, such as malignant hyperthermia and polymorphic ventricular tachycardia.
The Tarantula Toxin ω-Avsp1a Specifically Inhibits Human CaV3.1 and CaV3.3 via the Extracellular S3-S4 Loop of the Domain 1 Voltage-Sensor
Publisher: MDPI AG
Date: 04-05-2022
DOI: 10.3390/BIOMEDICINES10051066
Abstract: Inhibition of T-type calcium channels (CaV3) prevents development of diseases related to cardiovascular and nerve systems. Further, knockout animal studies have revealed that some diseases are mediated by specific subtypes of CaV3. However, subtype-specific CaV3 inhibitors for therapeutic purposes or for studying the physiological roles of CaV3 subtypes are missing. To bridge this gap, we employed our spider venom library and uncovered that Avicularia spec. (“Amazonas Purple”, Peru) tarantula venom inhibited specific T-type CaV channel subtypes. By using chromatographic and mass-spectrometric techniques, we isolated and sequenced the active toxin ω-Avsp1a, a C-terminally amidated 36 residue peptide with a molecular weight of 4224.91 Da, which comprised the major peak in the venom. Both native (4.1 μM) and synthetic ω-Avsp1a (10 μM) inhibited 90% of CaV3.1 and CaV3.3, but only 25% of CaV3.2 currents. In order to investigate the toxin binding site, we generated a range of chimeric channels from the less sensitive CaV3.2 and more sensitive CaV3.3. Our results suggest that domain-1 of CaV3.3 is important for the inhibitory effect of ω-Avsp1a on T-type calcium channels. Further studies revealed that a leucine of T-type calcium channels is crucial for the inhibitory effect of ω-Avsp1a.
Bioactive components in fish venoms
Publisher: MDPI AG
Date: 30-04-2015
Selective spider toxins reveal a role for the Nav1.1 channel in mechanical pain.
Publisher: Springer Science and Business Media LLC
Date: 06-06-2016
DOI: 10.1038/NATURE17976
A proteomic approach to detect lactosylation and other chemical changes in stored milk protein concentrate
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.FOODCHEM.2011.11.012
Abstract: Milk proteins undergo chemical changes such as lactosylation, deamidation and protein cross-linking during processing and storage of milk products. A proteomic technique combining two-dimensional gel electrophoresis and mass spectrometry was used to investigate chemical modifications to proteins, in milk protein concentrate (MPC80), during storage. Lactosylation, deamidation and protein cross-linking were observed on 2-DE gels. They were storage temperature-, humidity- and time-dependent. Lactosylated whey proteins were well separated on 2-DE in vertical stacks of spots. The masses of the spots varied by multiples of 324, indicating the attachment of lactose to lysine residues in the proteins. The trypsin-digested spots of α-lactalbumin were analysed by MALDI-TOF mass spectrometry, which indicated multiple lactosylation sites. The lactose adducts on gels were quantified by image analysis, allowing development of adducts over time to be monitored. The results show that proteomics can be used for the detection and quantification of chemical modifications to proteins in stored MPC80.
Atypical α-conotoxin LtIA from Conus litteratus targets a novel microsite of the α3β2 nicotinic receptor
Publisher: Elsevier BV
Date: 04-2010
α-conotoxin EpI, a novel sulfated peptide from Conus episcopatus that selectively targets neuronal nicotinic acetylcholine receptors
Publisher: Elsevier BV
Date: 06-1998
Modulatory features of the novel spider toxin μ-TRTX-Df1a isolated from the venom of the spider Davus fasciatus
Publisher: Wiley
Date: 27-06-2017
DOI: 10.1111/BPH.13865
The structural conformation of the tachykinin domain drives the anti-tumoural activity of an octopus peptide in melanoma BRAFV600E.
Publisher: Wiley
Date: 29-07-2022
DOI: 10.1111/BPH.15923
Abstract: Over past decades, targeted therapies and immunotherapy have improved survival and reduced the morbidity of patients with BRAF‐mutated melanoma. However, drug resistance and relapse hinder overall success. Therefore, there is an urgent need for novel compounds with therapeutic efficacy against BRAF‐melanoma. This prompted us to investigate the antiproliferative profile of a tachykinin‐peptide from the Octopus kaurna , Octpep‐1 in melanoma. We evaluated the cytotoxicity of Octpep‐1 by MTT assay. Mechanistic insights on viability and cellular damage caused by Octpep‐1 were gained via flow cytometry and bioenergetics. Structural and pharmacological characterization was conducted by molecular modelling, molecular biology, CRISPR/Cas9 technology, high‐throughput mRNA and calcium flux analysis. In vivo efficacy was validated in two independent xerograph animal models (mice and zebrafish). Octpep‐1 selectively reduced the proliferative capacity of human melanoma BRAF V600E ‐mutated cells with minimal effects on fibroblasts. In melanoma‐treated cells, Octpep‐1 increased ROS with unaltered mitochondrial membrane potential and promoted non‐mitochondrial and mitochondrial respiration with inefficient ATP coupling. Molecular modelling revealed that the cytotoxicity of Octpep‐1 depends upon the α‐helix and polyproline conformation in the C‐terminal region of the peptide. A truncated form of the C‐terminal end of Octpep‐1 displayed enhanced potency and efficacy against melanoma. Octpep‐1 reduced the progression of tumours in xenograft melanoma mice and zebrafish. We unravel the intrinsic anti‐tumoural properties of a tachykinin peptide. This peptide mediates the selective cytotoxicity in BRAF‐mutated melanoma in vitro and prevents tumour progression in vivo, providing a foundation for a therapy against melanoma.
Privileged frameworks from snake venom
Publisher: Springer Science and Business Media LLC
Date: 19-02-2015
DOI: 10.1007/S00018-015-1844-Z
Abstract: Venom as a form of chemical prey capture is a key innovation that has underpinned the explosive radiation of the advanced snakes (Caenophidia). Small venom proteins are often rich in disulfide bonds thus facilitating stable molecular scaffolds that present key functional residues on the protein surface. New toxin types are initially developed through the venom gland over-expression of normal body proteins, their subsequent gene duplication and ersification that leads to neofunctionalisation as random mutations modify their structure and function. This process has led to preferentially selected (privileged) cysteine-rich scaffolds that enable the snake to build arrays of toxins many of which may lead to therapeutic products and research tools. This review focuses on cysteine-rich small proteins and peptides found in snake venoms spanning natriuretic peptides to phospholipase enzymes, while highlighting their three-dimensional structures and biological functions as well as their potential as therapeutic agents or research tools.
A tarantula-venom peptide antagonizes the TRPA1 nociceptor Ion channel by binding to the S1-S4 gating domain
Publisher: Elsevier BV
Date: 03-2014
Transcriptome and proteome of Conus planorbis identify the nicotinic receptors as primary target for the defensive venom
Publisher: Wiley
Date: 17-11-2015
Abstract: Most venomous predators have evolved complex venom primarily to immobilize their prey and secondarily to defend against predators. In a new paradigm, carnivorous marine gastropods of the genus Conus were shown to rapidly and reversibly switch between two types of venoms in response to predatory or defensive stimulus, suggesting that the defensive use of venom may have a more important role in venom evolution and specialization than previously thought. To further investigate this phenomenon, the defensive repertoire of a vermivorous species, Conus planorbis, was deciphered using second-generation sequencing coupled to high-throughput proteomics. The venom gland transcriptome of C. planorbis revealed 182 unique conotoxin precursors from 25 gene superfamilies, with superfamily T dominating in terms of read and paralog numbers. Analysis of the defense-evoked venom revealed that this vermivorous species uses a similarly complex arsenal to deter aggressors as more recently evolved fish- and mollusk-hunting species, with MS/MS validating 23 conotoxin sequences from six superfamilies. Pharmacological characterization of the defensive venom on human receptors identified the nicotinic acetylcholine receptors as a primary target. This work provides the first insights into the composition and biological activity of specifically evolved defensive venoms in vermivorous cone snails.
Taipan Natriuretic Peptides Are Potent and Selective Agonists for the Natriuretic Peptide Receptor A
Publisher: MDPI AG
Date: 29-03-2023
DOI: 10.3390/MOLECULES28073063
Abstract: Cardiovascular ailments are a major cause of mortality where over 1.3 billion people suffer from hypertension leading to heart-disease related deaths. Snake venoms possess a broad repertoire of natriuretic peptides with therapeutic potential for treating hypertension, congestive heart failure, and related cardiovascular disease. We now describe several taipan (Oxyuranus microlepidotus) natriuretic peptides TNPa-e which stimulated cGMP production through the natriuretic peptide receptor A (NPR-A) with higher potencies for the rat NPR-A (rNPR-A) over human NPR-A (hNPR-A). TNPc and TNPd were the most potent, demonstrating 100- and 560-fold selectivity for rNPR-A over hNPR-A. In vivo studies found that TNPc decreased diastolic and systolic blood pressure (BP) and increased heart rate (HR) in conscious normotensive rabbits, to a level that was similar to that of human atrial natriuretic peptide (hANP). TNPc also enhanced the bradycardia due to cardiac afferent stimulation (Bezold–Jarisch reflex). This indicated that TNPc possesses the ability to lower blood pressure and facilitate cardiac vagal afferent reflexes but unlike hANP does not produce tachycardia. The 3-dimensional structure of TNPc was well defined within the pharmacophoric disulfide ring, displaying two turn-like regions (RMSD = 1.15 Å). Further, its much greater biological stability together with its selectivity and potency will enhance its usefulness as a biological tool.
Chemical synthesis and folding pathways of large cyclic polypeptides: Studies of the cystine knot polypeptide kalata B1
Publisher: American Chemical Society (ACS)
Date: 21-07-1999
DOI: 10.1021/BI990605B
Chemical engineering and structural and pharmacological characterization of the α-scorpion toxin OD1
Publisher: American Chemical Society (ACS)
Date: 03-04-2013
DOI: 10.1021/CB400012K
Abstract: Scorpion α-toxins are invaluable pharmacological tools for studying voltage-gated sodium channels, but few structure-function studies have been undertaken due to their challenging synthesis. To address this deficiency, we report a chemical engineering strategy based upon native chemical ligation. The chemical synthesis of α-toxin OD1 was achieved by chemical ligation of three unprotected peptide segments. A high resolution X-ray structure (1.8 Å) of synthetic OD1 showed the typical βαββ α-toxin fold and revealed important conformational differences in the pharmacophore region when compared with other α-toxin structures. Pharmacological analysis of synthetic OD1 revealed potent α-toxin activity (inhibition of fast inactivation) at Nav1.7, as well as Nav1.4 and Nav1.6. In addition, OD1 also produced potent β-toxin activity at Nav1.4 and Nav1.6 (shift of channel activation in the hyperpolarizing direction), indicating that OD1 might interact at more than one site with Nav1.4 and Nav1.6. Investigation of nine OD1 mutants revealed that three residues in the reverse turn contributed significantly to selectivity, with the triple OD1 mutant (D9K, D10P, K11H) being 40-fold more selective for Nav1.7 over Nav1.6, while OD1 K11V was 5-fold more selective for Nav1.6 than Nav1.7. This switch in selectivity highlights the importance of the reverse turn for engineering α-toxins with altered selectivity at Nav subtypes.
Deep venomics reveals the mechanism for expanded peptide diversity in cone snail venom
Publisher: Elsevier BV
Date: 02-2013
α-conotoxin AuIB isomers exhibit distinct inhibitory mechanisms and differential sensitivity to stoichiometry of α3β4 nicotinic acetylcholine receptors
Publisher: Elsevier BV
Date: 07-2010
Conopeptide-Derived κ-Opioid Agonists (Conorphins)
Publisher: American Chemical Society (ACS)
Date: 22-02-2016
DOI: 10.1021/ACS.JMEDCHEM.5B00911
Abstract: Opioid receptor screening of a conopeptide library led to a novel selective κ-opioid agonist peptide (conorphin T). Intensive medicinal chemistry, guided by potency, selectivity, and stability assays generated a pharmacophore model supporting rational design of highly potent and selective κ-opioid receptor (KOR) agonists (conorphins) with exceptional plasma stability. Conorphins are defined by a hydrophobic benzoprolyl moiety, a double arginine sequence, a spacer amino acid followed by a hydrophobic residue and a C-terminal vicinal disulfide moiety. The pharmacophore model was supported by computational docking studies, revealing receptor-ligand interactions similar to KOR agonist dynorphin A (1-8). A conorphin agonist inhibited colonic nociceptors in a mouse tissue model of chronic visceral hypersensitivity, suggesting the potential of KOR agonists for the treatment of chronic abdominal pain. This new conorphine KOR agonist class and pharmacophore model provide opportunities for future rational drug development and probes for exploring the role of the κ-opioid receptor.
Cysteine-rich mini-proteins in human biology
Publisher: Bentham Science Publishers Ltd.
Date: 08-2012
DOI: 10.2174/156802612802652411
Abstract: Understanding the relationship between structure and function underpins both biochemistry and chemical biology, and has enabled the discovery of numerous agricultural and therapeutic agents. Small cysteine-rich proteins, which form a unique set of protein frameworks and folds, are found in all living organisms and often play crucial roles as hormones, growth factors, ion channel modulators and enzyme inhibitors in various biological pathways. Here we review secreted human cysteine-rich mini-proteins, classify them into broad families and briefly describe their structure and function. To systematically investigate this protein sub-class we designed a step-wise high throughput algorithm that is able to isolate the mature and active forms of human secreted cysteine-rich proteins (up to 200 amino acids in length) and extract their cysteine scaffolds. We limited our search to frameworks that contain an even number of cysteine residues ( 5% cysteine residues led to the identification of 22 cysteine-rich frameworks representing 21 protein families. Analysis of their molecular targets showed that these mini-proteins are frequently ligands for G protein- and enzyme-coupled receptors, transporters, extracellular enzyme inhibitors, and antimicrobial peptides. It is clear that these human secreted mini-proteins possess a wide ersity of frameworks and folds, some of which are conserved across the phylogenetic spectrum. Further study of these proteins will undoubtedly lead to insights into unresolved questions of basic biology, and the development of system-specific human therapeutics.
The Deadly Toxin Arsenal of the Tree-Dwelling Australian Funnel-Web Spiders
Publisher: MDPI AG
Date: 28-10-2022
Abstract: Australian funnel-web spiders are amongst the most dangerous venomous animals. Their venoms induce potentially deadly symptoms, including hyper- and hypotension, tachycardia, bradycardia and pulmonary oedema. Human envenomation is more frequent with the ground-dwelling species, including the infamous Sydney funnel-web spider (Atrax robustus) although, only two tree-dwelling species induce more severe envenomation. To unravel the mechanisms that lead to this stark difference in clinical outcomes, we investigated the venom transcriptome and proteome of arboreal Hadronyche cerberea and H. formidabilis. Overall, Hadronyche venoms comprised 44 toxin superfamilies, with 12 being exclusive to tree-dwellers. Surprisingly, the major venom components were neprilysins and uncharacterized peptides, in addition to the well-known ω- and δ-hexatoxins and double-knot peptides. The insecticidal effects of Hadronyche venom on sheep blowflies were more potent than Atrax venom, and the venom of both tree- and ground-dwelling species potently modulated human voltage-gated sodium channels, particularly NaV1.2. Only the venom of tree-dwellers exhibited potent modulation of voltage-gated calcium channels. H. formidabilis appeared to be under less ersifying selection pressure compared to the newly adapted tree-dweller, H. cerberea. Thus, this study contributes to unravelling the fascinating molecular and pharmacological basis for the severe envenomation caused by the Australian tree-dwelling funnel-web spiders.
PHAB toxins: a unique family of predatory sea anemone toxins evolving via intra-gene concerted evolution defines a new peptide fold
Publisher: Springer Science and Business Media LLC
Date: 14-08-2018
DOI: 10.1007/S00018-018-2897-6
Abstract: Sea anemone venoms have long been recognized as a rich source of peptides with interesting pharmacological and structural properties, but they still contain many uncharacterized bioactive compounds. Here we report the discovery, three-dimensional structure, activity, tissue localization, and putative function of a novel sea anemone peptide toxin that constitutes a new, sixth type of voltage-gated potassium channel (K
Modern venom profiling: Mining into scorpion venom biodiversity
Publisher: Springer Netherlands
Date: 24-12-2015
Deep venomics of the Pseudonaja genus reveals inter- and intra-specific variation
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.JPROT.2015.11.019
Abstract: Australian elapid venom remains an under-investigated resource of novel bioactive peptides. In this study, the venom gland transcriptomes and proteomes of the Australian western brown snakes, Pseudonaja aspidorhyncha and Pseudonaja nuchalis, were compared to Pseudonaja textilis. A deep venomics strategy incorporating high throughput 454 pyrosequencing gave a total of 200,911 raw reads for the three venoms. Subsequent annotation identified 5716 transcripts from 20 different toxin families with inter-specific variation between species observed in eight of the less abundant families. Integration of each venom proteome with the corresponding annotated reads identified 65 isoforms from six toxin families high sequence coverage highlighted subtle differences between sequences and intra and inter-specific variation between species. High quality MS/MS data identified unusual glycoforms with natriuretic peptides from P. aspidorhyncha and P. nuchaliscontaining O-linked trisaccharides with high homology to the glycosylated region of TNPc. Molecular evolutionary assessments indicated the accelerated evolution of all toxin families with the exception of both natriuretic peptides and P. aspidorhyncha PLA2s that were found to be evolutionarily constrained under purifying selection pressures. This study has revealed a wide range of novel peptide sequences from six bioactive peptide families and highlights the subtle differences between toxins in these closely related species. Mining Australia's vastly untapped source of toxins from its venomous creatures has been significantly advanced by employing deep venomics methodology. Technological advances in transcriptome analysis using next generation sequencing platforms and proteome analysis by highly sensitive tandem mass spectrometry allowed a more comprehensive interrogation of three underinvestigated brown snake (Pseudonaja) venoms uncovering many novel peptide sequences that are unique to these closely related species. This generic strategy will provide invaluable information when applied to other venomous snakes for a deeper understanding of venom composition, envenomation, venom evolution, as well as identifying research tools and drug leads.
Understanding the molecular basis of toxin promiscuity: The analgesic sea anemone peptide APETx2 interacts with acid-sensing ion channel 3 and hERG channels via overlapping pharmacophores
Publisher: American Chemical Society (ACS)
Date: 04-11-2014
DOI: 10.1021/JM501400P
Abstract: The sea anemone peptide APETx2 is a potent and selective blocker of acid-sensing ion channel 3 (ASIC3). APETx2 is analgesic in a variety of rodent pain models, but the lack of knowledge of its pharmacophore and binding site on ASIC3 has impeded development of improved analogues. Here we present a detailed structure-activity relationship study of APETx2. Determination of a high-resolution structure of APETx2 combined with scanning mutagenesis revealed a cluster of aromatic and basic residues that mediate its interaction with ASIC3. We show that APETx2 also inhibits the off-target hERG channel by reducing the maximal current litude and shifting the voltage dependence of activation to more positive potentials. Electrophysiological screening of selected APETx2 mutants revealed partial overlap between the surfaces on APETx2 that mediate its interaction with ASIC3 and hERG. Characterization of the molecular basis of these interactions is an important first step toward the rational design of more selective APETx2 analogues.
Inhibition of Neuronal Nicotinic Acetylcholine Receptor Subtypes by α-Conotoxin GID and Analogues
Publisher: Elsevier BV
Date: 02-2009
Conotoxins: Chemistry and Biology
Publisher: American Chemical Society (ACS)
Date: 21-10-2019
DOI: 10.1021/ACS.CHEMREV.9B00207
Abstract: The venom of the marine predatory cone snails (genus
Venomics: A new paradigm for natural products-based drug discovery
Publisher: Springer Science and Business Media LLC
Date: 24-02-2011
DOI: 10.1007/S00726-010-0516-4
Abstract: The remarkable potency and pharmacological ersity of animal venoms has made them an increasingly valuable source of lead molecules for drug and insecticide discovery. Nevertheless, most of the chemical ersity encoded within these venoms remains uncharacterized, despite decades of research, in part because of the small quantities of venom available. However, recent advances in the miniaturization of bioassays and improvements in the sensitivity of mass spectrometry and NMR spectroscopy have allowed unprecedented access to the molecular ersity of animal venoms. Here, we discuss these technological developments in the context of establishing a high-throughput pipeline for venoms-based drug discovery.
Hydrophobic residues at position 10 of a-conotoxin PnIA influence subtype selectivity between α7 and α3β2 neuronal nicotinic acetylcholine receptors
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.BCP.2014.07.025
Abstract: Neuronal nicotinic acetylcholine receptors (nAChRs) are a erse class of ligand-gated ion channels involved in neurological conditions such as neuropathic pain and Alzheimer's disease. α-Conotoxin [A10L]PnIA is a potent and selective antagonist of the mammalian α7 nAChR with a key binding interaction at position 10. We now describe a molecular analysis of the receptor-ligand interactions that determine the role of position 10 in determining potency and selectivity for the α7 and α3β2 nAChR subtypes. Using electrophysiological and radioligand binding methods on a suite of [A10L]PnIA analogs we observed that hydrophobic residues in position 10 maintained potency at both subtypes whereas charged or polar residues abolished α7 binding. Molecular docking revealed dominant hydrophobic interactions with several α7 and α3β2 receptor residues via a hydrophobic funnel. Incorporation of norleucine (Nle) caused the largest (8-fold) increase in affinity for the α7 subtype (Ki=44nM) though selectivity reverted to α3β2 (IC50=0.7nM). It appears that the placement of a single methyl group determines selectivity between α7 and α3β2 nAChRs via different molecular determinants.
Pharmacological characterisation of the highly Na v 1.7 selective spider venom peptide Pn3a
Publisher: Springer Science and Business Media LLC
Date: 20-01-2017
DOI: 10.1038/SREP40883
Abstract: Human genetic studies have implicated the voltage-gated sodium channel Na V 1.7 as a therapeutic target for the treatment of pain. A novel peptide, μ-theraphotoxin-Pn3a, isolated from venom of the tarantula P hobeteus nigricolor, potently inhibits Na V 1.7 (IC 50 0.9 nM) with at least 40–1000-fold selectivity over all other Na V subtypes. Despite on-target activity in small-diameter dorsal root ganglia, spinal slices, and in a mouse model of pain induced by Na V 1.7 activation, Pn3a alone displayed no analgesic activity in formalin-, carrageenan- or FCA-induced pain in rodents when administered systemically. A broad lack of analgesic activity was also found for the selective Na V 1.7 inhibitors PF-04856264 and phlotoxin 1. However, when administered with subtherapeutic doses of opioids or the enkephalinase inhibitor thiorphan, these subtype-selective Na V 1.7 inhibitors produced profound analgesia. Our results suggest that in these inflammatory models, acute administration of peripherally restricted Na V 1.7 inhibitors can only produce analgesia when administered in combination with an opioid.
Comparative Venomics Reveals the Complex Prey Capture Strategy of the Piscivorous Cone Snail Conus catus
Publisher: American Chemical Society (ACS)
Date: 10-09-2015
DOI: 10.1021/ACS.JPROTEOME.5B00630
Abstract: Venomous marine cone snails produce a unique and remarkably erse range of venom peptides (conotoxins and conopeptides) that have proven to be invaluable as pharmacological probes and leads to new therapies. Conus catus is a hook-and-line fish hunter from clade I, with ∼20 conotoxins identified, including the analgesic ω-conotoxin CVID (AM336). The current study unravels the venom composition of C. catus with tandem mass spectrometry and 454 sequencing data. From the venom gland transcriptome, 104 precursors were recovered from 11 superfamilies, with superfamily A (especially κA-) conotoxins dominating (77%) their venom. Proteomic analysis confirmed that κA-conotoxins dominated the predation-evoked milked venom of each of six C. catus analyzed and revealed remarkable intraspecific variation in both the intensity and type of conotoxins. High-throughput FLIPR assays revealed that the predation-evoked venom contained a range of conotoxins targeting the nAChR, Cav, and Nav ion channels, consistent with α- and ω-conotoxins being used for predation by C. catus. However, the κA-conotoxins did not act at these targets but induced potent and rapid immobilization followed by bursts of activity and finally paralysis when injected intramuscularly in zebrafish. Our venomics approach revealed the complexity of the envenomation strategy used by C. catus, which contains a mix of both excitatory and inhibitory venom peptides.
Isolation and structure-activity of mu-conotoxin TIIIA, a potent inhibitor of tetrodotoxin-sensitive voltage-gated sodium channels.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 12-2006
Abstract: Mu-conotoxins are three-loop peptides produced by cone snails to inhibit voltage-gated sodium channels during prey capture. Using polymerase chain reaction techniques, we identified a gene sequence from the venom duct of Conus tulipa encoding a new mu-conotoxin-TIIIA (TIIIA). A 125I-TIIIA binding assay was established to isolate native TIIIA from the crude venom of Conus striatus. The isolated peptide had three post-translational modifications, including two hydroxyproline residues and C-terminal amidation, and <35% homology to other mu-conotoxins. TIIIA potently displaced [3H]saxitoxin and 125I-TIIIA from rat brain (Nav1.2) and skeletal muscle (Nav1.4) membranes. Alanine and glutamine scans of TIIIA revealed several residues, including Arg14, that were critical for high-affinity binding to tetrodotoxin (TTX)-sensitive Na+ channels. We were surprised to find that [E15A]TIIIA had a 10-fold higher affinity than TIIIA for TTX-sensitive sodium channels (IC50, 15 vs. 148 pM at rat brain membrane). TIIIA was selective for Nav1.2 and -1.4 over Nav1.3, -1.5, -1.7, and -1.8 expressed in Xenopus laevis oocytes and had no effect on rat dorsal root ganglion neuron Na+ current. 1H NMR studies revealed that TIIIA adopted a single conformation in solution that was similar to the major conformation described previously for mu-conotoxin PIIIA. TIIIA and analogs provide new biochemical probes as well as insights into the structure-activity of mu-conotoxins.
MrIC, a novel α-conotoxin agonist in the presence of PNU at endogenous α7 nicotinic acetylcholine receptors
Publisher: American Chemical Society (ACS)
Date: 30-12-2014
DOI: 10.1021/BI400882S
Abstract: α-Conotoxins are competitive antagonists of nicotinic acetylcholine receptors (nAChRs). Their high selectivity and affinity for the various subtypes of nAChRs have led to significant advances in our understanding of the structure and function of these key ion channels. Here we report the discovery of a novel 4/7 α-conotoxin, MrIC from the venom duct of Conus marmoreus, which acts as an agonist at the endogenous human α7 nAChR in SH-SY5Y cells pretreated with PNU120596 (PNU). This unique agonist activity of MrIC at α7 nAChRs may guide the development of novel α7 nAChR modulators.
Trends in peptide drug discovery
Publisher: Springer Science and Business Media LLC
Date: 03-02-2021
DOI: 10.1038/S41573-020-00135-8
Abstract: Since the introduction of insulin almost a century ago, more than 80 peptide drugs have reached the market for a wide range of diseases, including diabetes, cancer, osteoporosis, multiple sclerosis, HIV infection and chronic pain. In this Perspective, we summarize key trends in peptide drug discovery and development, covering the early efforts focused on human hormones, elegant medicinal chemistry and rational design strategies, peptide drugs derived from nature, and major breakthroughs in molecular biology and peptide chemistry that continue to advance the field. We emphasize lessons from earlier approaches that are still relevant today as well as emerging strategies such as integrated venomics and peptide-display libraries that create new avenues for peptide drug discovery. We also discuss the pharmaceutical landscape in which peptide drugs could be particularly valuable and analyse the challenges that need to be addressed for them to reach their full potential.
Solution structure of μ-conotoxin PIIIA, a preferential inhibitor of persistent tetrodotoxin-sensitive sodium channels
Publisher: Elsevier BV
Date: 07-2002
Systematic interrogation of the Conus marmoreus venom duct transcriptome with ConoSorter reveals 158 novel conotoxins and 13 new gene superfamilies
Publisher: Springer Science and Business Media LLC
Date: 16-10-2013
Abstract: Conopeptides, often generically referred to as conotoxins, are small neurotoxins found in the venom of predatory marine cone snails. These molecules are highly stable and are able to efficiently and selectively interact with a wide variety of heterologous receptors and channels, making them valuable pharmacological probes and potential drug leads. Recent advances in next-generation RNA sequencing and high-throughput proteomics have led to the generation of large data sets that require purpose-built and dedicated bioinformatics tools for efficient data mining. Here we describe ConoSorter, an algorithm that categorizes cDNA or protein sequences into conopeptide superfamilies and classes based on their signal, pro- and mature region sequence composition. ConoSorter also catalogues key sequence characteristics (including relative sequence frequency, length, number of cysteines, N-terminal hydrophobicity, sequence similarity score) and automatically searches the ConoServer database for known precursor sequences, facilitating identification of known and novel conopeptides. When applied to ConoServer and UniProtKB/Swiss-Prot databases, ConoSorter is able to recognize 100% of known conotoxin superfamilies and classes with a minimum species specificity of 99%. As a proof of concept, we performed a reanalysis of Conus marmoreus venom duct transcriptome and (i) correctly classified all sequences previously annotated, (ii) identified 158 novel precursor conopeptide transcripts, 106 of which were confirmed by protein mass spectrometry, and (iii) identified another 13 novel conotoxin gene superfamilies. Taken together, these findings indicate that ConoSorter is not only capable of robust classification of known conopeptides from large RNA data sets, but can also facilitate de novo identification of conopeptides which may have pharmaceutical importance.
Do Vicinal Disulfide Bridges Mediate Functionally Important Redox Transformations in Proteins?
Publisher: Mary Ann Liebert Inc
Date: 12-2013
Conopressin-T from Conus tulipa reveals an antagonist switch in vasopressin-like peptides
Publisher: Elsevier BV
Date: 03-2008
In situ neutralization in boc-chemistry solid phase peptide synthesis: Rapid, high yield assembly of difficult sequences
Publisher: Springer Science and Business Media LLC
Date: 10-01-2007
Isolation and characterisation of conomap-Vt, a d-amino acid containing excitatory peptide from the venom of a vermivorous cone snail
Publisher: Wiley
Date: 16-06-2006
DOI: 10.1016/J.FEBSLET.2006.06.011
Abstract: Cone snail venom is a rich source of bioactives, in particular small disulfide rich peptides that disrupt synaptic transmission. Here, we report the discovery of conomap-Vt (Conp-Vt), an unusual linear tetradecapeptide isolated from Conus vitulinus venom. The sequence displays no homology to known conopeptides, but displays significant homology to peptides of the MATP (myoactive tetradecapeptide) family, which are important endogenous neuromodulators in molluscs, annelids and insects. Conp-Vt showed potent excitatory activity in several snail isolated tissue preparations. Similar to ACh, repeated doses of Conp-Vt were tachyphylactic. Since nicotinic and muscarinic antagonists failed to block its effect and Conp-Vt desensitised tissue remained responsive to ACh, it appears that Conp-Vt contractions were non-cholinergic in origin. Finally, biochemical studies revealed that Conp-Vt is the first member of the MATP family with a d-amino acid. Interestingly, the isomerization of L-Phe to D-Phe enhanced biological activity, suggesting that this post-translational modified conopeptide may have evolved for prey capture.
Neuronally micro-conotoxins from Conus striatus utilize an alpha-helical motif to target mammalian sodium channels.
Publisher: Elsevier BV
Date: 08-0005
β-turn topography
Publisher: Elsevier BV
Date: 03-1993
α-conotoxins PnIA and [A10L]PnIA stabilize different states of the α7-L247T nicotinic acetylcholine receptor
Publisher: Elsevier BV
Date: 07-2003
Conotoxin TVIIA, a novel peptide from the venom of Conus tulipa. 2. Three-dimensional solution structure
Publisher: Wiley
Date: 08-2000
DOI: 10.1046/J.1432-1327.2000.01507.X
Abstract: The three-dimensional solution structure of conotoxin TVIIA, a 30-residue polypeptide from the venom of the piscivorous cone snail Conus tulipa, has been determined using 2D 1H NMR spectroscopy. TVIIA contains six cysteine residues which form a 'four-loop' structural framework common to many peptides from Conus venoms including the omega-, delta-, kappa-, and muO-conotoxins. However, TVIIA does not belong to these well-characterized pharmacological classes of conotoxins, but displays high sequence identity with conotoxin GS, a muscle sodium channel blocker from Conus geographus. Structure calculations were based on 562 interproton distance restraints inferred from NOE data, together with 18 backbone and nine side-chain torsion angle restraints derived from spin-spin coupling constants. The final family of 20 structures had mean pairwise rms differences over residues 2-27 of 0.18+/-0.05 A for the backbone atoms and 1.39+/-0.33 A for all heavy atoms. The structure consists of a triple-stranded, antiparallel beta sheet with +2x, -1 topology (residues 7-9, 16-20 and 23-27) and several beta turns. The core of the molecule is formed by three disulfide bonds which form a cystine knot motif common to many toxic and inhibitory polypeptides. The global fold, molecular shape and distribution of amino-acid sidechains in TVIIA is similar to that previously reported for conotoxin GS, and comparison with other four-loop conotoxin structures provides further indication that TVIIA and GS represent a new and distinct subgroup of this structural family. The structure of TVIIA determined in this study provides the basis for determining a structure-activity relationship for these molecules and their interaction with target receptors.
Two new classes of conopeptides inhibit the α1-adrenoceptor and noradrenaline transporter
Publisher: Springer Science and Business Media LLC
Date: 06-08-2001
DOI: 10.1038/NN0901-902
Effects of arginine 10 to lysine substitution on ω-conotoxin CVIE and CVIF block of Cav 2.2 channels
Publisher: Wiley
Date: 10-06-2014
DOI: 10.1111/BPH.12686
Analgesic ω-conotoxins CVIE and CVIF selectively and voltage-dependently block recombinant and native N-type calcium channels (Molecular Pharmacology (2010) 77, (139-148))
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 14-07-2011
DOI: 10.1124/MOL.80.2.356
Identification of a Novel Class of Nicotinic Receptor Antagonists
Publisher: Elsevier BV
Date: 08-2006
Subtle modifications to oxytocin produce ligands that retain potency and improved selectivity across species.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-12-2017
DOI: 10.1126/SCISIGNAL.AAN3398
Abstract: An oxytocin derivative that may not trigger adverse side effects has been generated.
Accelerated chemical synthesis of peptides and small proteins
Publisher: Proceedings of the National Academy of Sciences
Date: 16-02-1999
Abstract: The chemical synthesis of peptides and small proteins is a powerful complementary strategy to recombinant protein overexpression and is widely used in structural biology, immunology, protein engineering, and biomedical research. Despite considerable improvements in the fidelity of peptide chain assembly, side-chain protection, and postsynthesis analysis, a limiting factor in accessing polypeptides containing greater than 50 residues remains the time taken for chain assembly. The ultimate goal of this work is to establish highly efficient chemical procedures that achieve chain-assembly rates of approximately 10–15 residues per hour, thus underpinning the rapid chemical synthesis of long polypeptides and proteins, including cytokines, growth factors, protein domains, and small enzymes. Here we report Boc chemistry that employs O -(7-azabenzotriazol-1-yl)- N,N,N ′ ,N ′-tetramethyluronium hexafluorophosphate (HATU)/dimethyl sulfoxide in situ neutralization as the coupling agent and incorporates a protected amino acid residue every 5 min to produce peptides of good quality. This rapid coupling chemistry was successfully demonstrated by synthesizing several small to medium peptides, including the “difficult” C-terminal sequence of HIV-1 proteinase (residues 81–99) fragment 65–74 of the acyl carrier protein conotoxin PnIA(A10L), a potent neuronal nicotinic receptor antagonist and the pro-inflammatory chemotactic protein CP10, an 88-residue protein, by means of native chemical ligation. The benefits of this approach include enhanced ability to identify and characterize “difficult couplings,” rapid access to peptides for biological and structure–activity studies, and accelerated synthesis of tailored large peptide segments ( residues) for use in chemoselective ligation methods.
Chemical and Functional Identification and Characterization of Novel Sulfated α-Conotoxins from the Cone Snail Conus anemone
Publisher: American Chemical Society (ACS)
Date: 29-01-2004
DOI: 10.1021/JM031010O
Abstract: An LC/MS analysis with diagnostic screening for the detection of peptides with posttranslational modifications revealed the presence of novel sulfated peptides within the alpha-conotoxin molecular mass range in Conus anemone crude venom. A functional assay of the extract showed activity at several neuronal nicotinic acetylcholine receptors (nAChRs). Three sulfated alpha-conotoxins (AnIA, AnIB, and AnIC) were identified by LC/MS and assay-directed fractionation and sequenced after purification. The most active of these, alpha-AnIB, was further characterized and used to investigate the influence of posttranslational modifications on affinity. Synthetic AnIB exhibited subnanomolar potency at the rat alpha3beta2 nAChR (IC50 0.3 nM) and was 200-fold less active on the rat alpha7 nAChR (IC50 76 nM). The unsulfated peptide [Tyr16]AnIB showed a 2-fold and 10-fold decrease in activities at alpha3beta2 (IC50 0.6 nM) and alpha7 (IC50 836 nM) nAChR, respectively. Likewise, removal of the C-terminal amide had a greater influence on potency at the alpha7 (IC50 367 nM) than at the alpha3beta2 nAChR (IC50 0.5 nM). Stepwise removal of two N-terminal glycine residues revealed that these residues affect the binding kinetics of the peptide. Comparison with similar 4/7-alpha-conotoxin sequences suggests that residue 11 (alanine or glycine) and residue 14 (glutamine) constitute important determinants for alpha3beta2 selectivity, whereas the C-terminal amidation and sulfation at tyrosine-16 favor alpha7 affinity.
Selenoether oxytocin analogues have analgesic properties in a mouse model of chronic abdominal pain
Publisher: Springer Science and Business Media LLC
Date: 30-01-2014
DOI: 10.1038/NCOMMS4165
Abstract: Poor oral availability and susceptibility to reduction and protease degradation is a major hurdle in peptide drug development. However, drugable receptors in the gut present an attractive niche for peptide therapeutics. Here we demonstrate, in a mouse model of chronic abdominal pain, that oxytocin receptors are significantly upregulated in nociceptors innervating the colon. Correspondingly, we develop chemical strategies to engineer non-reducible and therefore more stable oxytocin analogues. Chemoselective selenide macrocyclization yields stabilized analogues equipotent to native oxytocin. Ultra-high-field nuclear magnetic resonance structural analysis of native oxytocin and the seleno-oxytocin derivatives reveals that oxytocin has a pre-organized structure in solution, in marked contrast to earlier X-ray crystallography studies. Finally, we show that these seleno-oxytocin analogues potently inhibit colonic nociceptors both in vitro and in vivo in mice with chronic visceral hypersensitivity. Our findings have potentially important implications for clinical use of oxytocin analogues and disulphide-rich peptides in general.
Δ‐Myrtoxin‐Mp1a is a Helical Heterodimer from the Venom of the Jack Jumper Ant that has Antimicrobial, Membrane‐Disrupting, and Nociceptive Activities
Publisher: Wiley
Date: 13-06-2017
Abstract: Δ-Myrtoxin-Mp1a (Mp1a), a 49-residue heterodimeric peptide from the venom of Myrmecia pilosula, comprises a 26-mer A chain and a 23-mer B chain connected by two disulfide bonds in an antiparallel arrangement. Combination of the in idual synthetic chains through aerial oxidation remarkably resulted in the self-assembly of Mp1a as a homogenous product without the need for directed disulfide-bond formation. NMR analysis revealed a well-defined, unique structure containing an antiparallel α-helix pair. Dual polarization interferometry (DPI) analysis showed strong interaction with supported lipid bilayers and insertion within the bilayers. Mp1a caused non-specific Ca
Cysteine-Rich α-Conotoxin SII Displays Novel Interactions at the Muscle Nicotinic Acetylcholine Receptor
Publisher: American Chemical Society (ACS)
Date: 31-03-2022
DOI: 10.1021/ACSCHEMNEURO.1C00857
Abstract: α-Conotoxins that target muscle nicotinic acetylcholine receptors (nAChRs) commonly fall into two structural classes, frameworks I and II containing two and three disulfide bonds, respectively. Conotoxin SII is the sole member of the cysteine-rich framework II with ill-defined interactions at the nAChRs. Following directed synthesis of α-SII, NMR analysis revealed a well-defined structure containing a 3
Three-dimensional solution structure of α-conotoxin MII by NMR spectroscopy effects of solution environment on helicity
Publisher: American Chemical Society (ACS)
Date: 23-10-1998
DOI: 10.1021/BI981535W
Multitarget nociceptor sensitization by a promiscuous peptide from the venom of the King Baboon spider
Publisher: Proceedings of the National Academy of Sciences
Date: 24-01-2022
Abstract: Pain development and discomfort are universal features of spider envenomation, yet severe pain arising from bites by Old World spiders is poorly understood. Molecular analyses of the venom of the King Baboon spider revealed abundant expression of the inhibitory cystine knot peptide Pm1a. Synthetic Pm1a induces pain in mice while simultaneously enhancing proexcitatory sodium currents and decreasing inhibitory potassium currents. These concomitant effects promote hyperexcitability in pain-sensing neurons that can be reversed by pharmacological inhibition of voltage-gated sodium channels. The coordinated modulation of excitatory and inhibitory ion channels involved in pain propagation may represent an economical and effective defense strategy in pain-inducing defensive venoms.
Rapid access to ω-conotoxin chimeras using native chemical ligation
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/CH09216
Abstract: Grafting different regions of related peptides together to form a single protein chimera is a valuable tool in rapidly elucidating regions of activity or selectivity in peptides and proteins. To conveniently evaluate the contributions of the N- and C-terminal segments of ω-conotoxins CVID and MVIIC to activity, we employed native chemical ligation in CVID-MVIIC chimera design. Assembly of these peptide segments via the ligation method improved overall yield and coupling efficiency, with no difficult sequences encountered in contrast to the traditional full-length chain assembly of CVID. Radio-ligand binding assays revealed regions of importance for receptor recognition.
Intraspecific variations in Conus geographus defence-evoked venom and estimation of the human lethal dose
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.TOXICON.2014.09.011
Abstract: Conus geographus is the most dangerous cone snail species known, with reported human fatality rates as high as 65%. Crude venom gland extracts have been used to determine animal LD50 and to aid the isolation of several potent paralytic toxins. However, not only is the composition of injected venoms known to differ significantly from that in dissected venom glands, but also to vary according to predatory or defensive stimuli. Therefore, to study the venom that is directly relevant to human envenomation, the defense-evoked venom of several specimens of C. geographus was collected and analyzed by standard LC-MS methods. The molecular composition of in idual defense-evoked venom showed significant intraspecific variations, but a core of paralytic conotoxins including α-GI, α-GII, μ-GIIIA, ω-GVIA and ω-GVIIA was always present in large amounts, consistent with the symptomology and high fatality rate in humans. Differences between injected and dissected venoms obtained from the same specimen were also evident. Interestingly, an apparent linear correlation between the dry weight/volume of injected venom and the size of the shell allowed extrapolation to a human lethal dose (0.038-0.029 mg/kg) from an historic fatal case of C. geographus envenomation, which may help in the management of future victims.
Analgesic ω-conotoxins CVIE and CVIF selectively and voltage-dependently block recombinant and native N-type calcium channels
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 05-11-2010
Abstract: Neuronal (N)-type Ca(2+) channel-selective omega-conotoxins have emerged as potential new drugs for the treatment of chronic pain. In this study, two new omega-conotoxins, CVIE and CVIF, were discovered from a Conus catus cDNA library. Both conopeptides potently displaced (125)I-GVIA binding to rat brain membranes. In Xenopus laevis oocytes, CVIE and CVIF potently and selectively inhibited depolarization-activated Ba(2+) currents through recombinant N-type (alpha1(B-b)/alpha(2)delta1/beta(3)) Ca(2+) channels. Recovery from block increased with membrane hyperpolarization, indicating that CVIE and CVIF have a higher affinity for channels in the inactivated state. The link between inactivation and the reversibility of omega-conotoxin action was investigated by creating molecular ersity in beta subunits: N-type channels with beta(2a) subunits almost completely recovered from CVIE or CVIF block, whereas those with beta(3) subunits exhibited weak recovery, suggesting that reversibility of the omega-conotoxin block may depend on the type of beta-subunit isoform. In rat dorsal root ganglion sensory neurons, neither peptide had an effect on low-voltage-activated T-type channels but potently and selectively inhibited high voltage-activated N-type Ca(2+) channels in a voltage-dependent manner. In rat spinal cord slices, both peptides reversibly inhibited excitatory monosynaptic transmission between primary afferents and dorsal horn superficial lamina neurons. Homology models of CVIE and CVIF suggest that omega-conotoxin/voltage-gated Ca(2+) channel interaction is dominated by ionic/electrostatic interactions. In the rat partial sciatic nerve ligation model of neuropathic pain, CVIE and CVIF (1 nM) significantly reduced allodynic behavior. These N-type Ca(2+) channel-selective omega-conotoxins are therefore useful as neurophysiological tools and as potential therapeutic agents to inhibit nociceptive pain pathways.
Novel ω-conotoxins from C. catus reverse signs of mouse inflammatory pain after systemic administration
Publisher: SAGE Publications
Date: 2013
Abstract: Antagonists of N-type voltage-gated calcium channels (VGCC), Ca v 2.2, can manage severe chronic pain with intrathecal use and may be effective systemically. A series of novel ω-conotoxins that selectively inhibit N-type VGCCs was isolated from Conus catus. In the present study, the potency and reversibility of ω-conotoxins CVID, CVIE and CVIF to inhibit N-type calcium currents were investigated in mouse isolated dorsal root ganglion (DRG) neurons. The systemic potency of each ω-conotoxin to reverse signs of mouse chronic inflammatory pain was also compared. In DRG neurons, the rank order of potency to inhibit N-type calcium currents was CVIE CVIF CVID. After subcutaneous administration, CVID and CVIE, but not CVIF, partially reversed impaired weight bearing in mice injected with Freund's complete adjuvant (CFA) three days prior to testing. No side-effects associated with systemic administration of ω-conotoxins were observed. The present study indicates a potential for CVID and CVIE to be developed as systemically active analgesics with no accompanying neurological side-effects.
Rapid sensitive analysis of cysteine rich peptide venom components
Publisher: Proceedings of the National Academy of Sciences
Date: 28-04-2009
Abstract: Disulfide-rich peptide venoms from animals such as snakes, spiders, scorpions, and certain marine snails represent one of nature's great ersity libraries of bioactive molecules. The various species of marine cone shells have alone been estimated to produce ,000 distinct peptide venoms. These peptides have stimulated considerable interest because of their ability to potently alter the function of specific ion channels. To date, only a small fraction of this immense resource has been characterized because of the difficulty in elucidating their primary structures, which range in size between 10 and 80 aa, include up to 5 disulfide bonds, and can contain extensive posttranslational modifications. The extraordinary complexity of crude venoms and the lack of DNA databases for many of the organisms of interest present major analytical challenges. Here, we describe a strategy that uses mass spectrometry for the elucidation of the mature peptide toxin components of crude venom s les. Key to this strategy is our use of electron transfer dissociation (ETD), a mass spectrometric fragmentation technique that can produce sequence information across the entire peptide backbone. However, because ETD only yields comprehensive sequence coverage when the charge state of the precursor peptide ion is sufficiently high and the m / z ratio is low, we combined ETD with a targeted chemical derivatization strategy to increase the charge state of cysteine-containing peptide toxins. Using this strategy, we obtained full sequences for 31 peptide toxins, using just 7% of the crude venom from the venom gland of a single cone snail ( Conus textile ).
Conotoxin Φ‐MiXXVIIA from the Superfamily G2 Employs a Novel Cysteine Framework that Mimics Granulin and Displays Anti‐Apoptotic Activity
Publisher: Wiley
Date: 24-10-2017
Abstract: Conotoxins are a large family of disulfide-rich peptides that contain unique cysteine frameworks that target a broad range of ion channels and receptors. We recently discovered the 33-residue conotoxin Φ-MiXXVIIA from Conus miles with a novel cysteine framework comprising three consecutive cysteine residues and four disulfide bonds. Regioselective chemical synthesis helped decipher the disulfide bond connectivity and the structure of Φ-MiXXVIIA was determined by NMR spectroscopy. The 3D structure displays a unique topology containing two β-hairpins that resemble the N-terminal domain of granulin. Similar to granulin, Φ-MiXXVIIA promotes cell proliferation (EC
Development of a human vasopressin V1a-receptor antagonist from an evolutionary-related insect neuropeptide
Publisher: Springer Science and Business Media LLC
Date: 02-2017
DOI: 10.1038/SREP41002
Abstract: Characterisation of G protein-coupled receptors (GPCR) relies on the availability of a toolbox of ligands that selectively modulate different functional states of the receptors. To uncover such molecules, we explored a unique strategy for ligand discovery that takes advantage of the evolutionary conservation of the 600-million-year-old oxytocin/vasopressin signalling system. We isolated the insect oxytocin/vasopressin orthologue inotocin from the black garden ant ( Lasius niger ), identified and cloned its cognate receptor and determined its pharmacological properties on the insect and human oxytocin/vasopressin receptors. Subsequently, we identified a functional dichotomy: inotocin activated the insect inotocin and the human vasopressin V 1b receptors, but inhibited the human V 1a R. Replacement of Arg8 of inotocin by D-Arg8 led to a potent, stable and competitive V 1a R-antagonist ([D-Arg8]-inotocin) with a 3,000-fold binding selectivity for the human V 1a R over the other three subtypes, OTR, V 1b R and V 2 R. The Arg8/D-Arg8 ligand-pair was further investigated to gain novel insights into the oxytocin/vasopressin peptide-receptor interaction, which led to the identification of key residues of the receptors that are important for ligand functionality and selectivity. These observations could play an important role for development of oxytocin/vasopressin receptor modulators that would enable clear distinction of the physiological and pathological responses of the in idual receptor subtypes.
Allosteric α1-Adrenoreceptor Antagonism by the Conopeptide ρ-TIA
Publisher: Elsevier BV
Date: 09-2003
Discovery, synthesis, and structure-activity relationships of conotoxins
Publisher: American Chemical Society (ACS)
Date: 10-04-2014
DOI: 10.1021/CR400401E
Mapping the Molecular Surface of the Analgesic NaV1.7-Selective Peptide Pn3a Reveals Residues Essential for Membrane and Channel Interactions
Publisher: American Chemical Society (ACS)
Date: 19-02-2020
Transcriptomic messiness in the venom duct of conus miles contributes to conotoxin diversity
Publisher: Elsevier BV
Date: 12-2013
Novel venom-derived inhibitors of the human EAG channel, a putative antiepileptic drug target
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.BCP.2018.08.038
Abstract: Recently, we and other groups revealed that gain-of-function mutations in the human ether à go-go voltage-gated potassium channel hEAG1 (K
Solution structure of α-conotoxin ImI by 1H nuclear magnetic resonance
Publisher: American Chemical Society (ACS)
Date: 11-06-1999
DOI: 10.1021/JM990114P
Nature-inspired dimerization as a strategy to modulate neuropeptide pharmacology exemplified with vasopressin and oxytocin
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0SC05501H
Abstract: Structural and pharmacological study of parallel, antiparallel and N- to C-terminal cyclized homo- and heterodimers of vasopressin and oxytocin. This study spotlights dimerization as a strategy to modulate the pharmacology of neuropeptides.
Cone snail venomics: From novel biology to novel therapeutics
Publisher: Future Science Ltd
Date: 10-2014
DOI: 10.4155/FMC.14.99
Abstract: Peptide neurotoxins from cone snails called conotoxins are renowned for their therapeutic potential to treat pain and several neurodegenerative diseases. Inefficient assay-guided discovery methods have been replaced by high-throughput bioassays integrated with advanced MS and next-generation sequencing, ushering in the era of ‘venomics’. In this review, we focus on the impact of venomics on the understanding of cone snail biology as well as the application of venomics to accelerate the discovery of new conotoxins. We also discuss the continued importance of medicinal chemistry approaches to optimize conotoxins for clinical use, with a descriptive case study of MrIA featured.
Conotoxin TVIIA, a novel peptide from the venom of Conus tulipa: 1. Isolation, characterization and chemical synthesis
Publisher: Wiley
Date: 08-2000
DOI: 10.1046/J.1432-1327.2000.01508.X
Abstract: A novel conotoxin belonging to the 'four-loop' structural class has been isolated from the venom of the piscivorous cone snail Conus tulipa. It was identified using a chemical-directed strategy based largely on mass spectrometric techniques. The new toxin, conotoxin TVIIA, consists of 30 amino-acid residues and contains three disulfide bonds. The amino-acid sequence was determined by Edman analysis as SCSGRDSRCOOVCCMGLMCSRGKCVSIYGE where O = 4-transL-hydroxyproline. Two under-hydroxylated analogues, [Pro10]TVIIA and [Pro10,11]TVIIA, were also identified in the venom of C. tulipa. The sequences of TVIIA and [Pro10]TVIIA were further verified by chemical synthesis and coelution studies with native material. Conotoxin TVIIA has a six cysteine/four-loop structural framework common to many peptides from Conus venoms including the omega-, delta- and kappa-conotoxins. However, TVIIA displays little sequence homology with these well-characterized pharmacological classes of peptides, but displays striking sequence homology with conotoxin GS, a peptide from Conus geographus that blocks skeletal muscle sodium channels. These new toxins and GS share several biochemical features and represent a distinct subgroup of the four-loop conotoxins.
Isolation, characterization and total regioselective synthesis of the novel μo-conotoxin MfVIA from Conus magnificus that targets voltage-gated sodium channels
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.BCP.2012.05.008
Abstract: The μO-conotoxins are notable for their unique selectivity for Na(v)1.8 over other sodium channel isoforms, making them attractive drug leads for the treatment of neuropathic pain. We describe the discovery of a novel μO-conotoxin, MfVIA, from the venom of Conus magnificus using high-throughput screening approaches. MfVIA was found to be a hydrophobic 32-residue peptide (amino acid sequence RDCQEKWEYCIVPILGFVYCCPGLICGPFVCV) with highest sequence homology to μO-conotoxin MrVIB. To overcome the synthetic challenges posed by μO-conotoxins due to their hydrophobic nature and difficult folding, we developed a novel regioselective approach for the synthesis of μO-conotoxins. Performing selective oxidative deprotections of the cysteine side-chain protecting groups of the fully protected peptide allowed manipulations in organic solvents with no chromatography required between steps. Using this approach, we obtained correctly folded MfVIA with increased synthetic yields. Biological activity of MfVIA was assessed using membrane potential-sensitive dyes and electrophysiological recording techniques. MfVIA preferentially inhibits Na(v)1.8 (IC₅₀ 95.9±74.3 nM) and Na(v)1.4 (IC₅₀ 81±16 nM), with significantly lower affinity for other Na(v) subtypes (IC₅₀ 431-6203 nM Na(v)1.5>1.6∼1.7∼1.3∼1.1∼1.2). This improved approach to μO-conotoxin synthesis will facilitate the optimization of μO-conotoxins as novel analgesic molecules to improve pain management.
Venomics Reveals Venom Complexity of the Piscivorous Cone Snail, Conus tulipa
Publisher: MDPI AG
Date: 21-01-2019
DOI: 10.3390/MD17010071
Abstract: The piscivorous cone snail Conus tulipa has evolved a net-hunting strategy, akin to the deadly Conus geographus, and is considered the second most dangerous cone snail to humans. Here, we present the first venomics study of C. tulipa venom using integrated transcriptomic and proteomic approaches. Parallel transcriptomic analysis of two C. tulipa specimens revealed striking differences in conopeptide expression levels (2.5-fold) between in iduals, identifying 522 and 328 conotoxin precursors from 18 known gene superfamilies. Despite broad overlap at the superfamily level, only 86 precursors (11%) were common to both specimens. Conantokins (NMDA antagonists) from the superfamily B1 dominated the transcriptome and proteome of C. tulipa venom, along with superfamilies B2, A, O1, O3, con-ikot-ikot and conopressins, plus novel putative conotoxins precursors T1.3, T6.2, T6.3, T6.4 and T8.1. Thus, C. tulipa venom comprised both paralytic (putative ion channel modulating α-, ω-, μ-, δ-) and non-paralytic (conantokins, con-ikot-ikots, conopressins) conotoxins. This venomic study confirms the potential for non-paralytic conotoxins to contribute to the net-hunting strategy of C. tulipa.
Isolation, Structure, and Activity of GID, a Novel α4/7-Conotoxin with an Extended N-terminal Sequence
Publisher: Elsevier BV
Date: 2003
D-amino acid residue in the C-type natriuretic peptide from the venom of the mammal, Ornithorhynchus anatinus, the Australian platypus
Publisher: Wiley
Date: 12-07-2002
DOI: 10.1016/S0014-5793(02)03050-8
Abstract: The C-type natriuretic peptide from the platypus venom (OvCNP) exists in two forms, OvCNPa and OvCNPb, whose amino acid sequences are identical. Through the use of nuclear magnetic resonance, mass spectrometry, and peptidase digestion studies, we discovered that OvCNPb incorporates a D-amino acid at position 2 in the primary structure. Peptides containing a D-amino acid have been found in lower forms of organism, but this report is the first for a D-amino acid in a biologically active peptide from a mammal. The result implies the existence of a specific isomerase in the platypus that converts an L-amino acid residue in the protein to the D-configuration.
Activation of κ Opioid Receptors in Cutaneous Nerve Endings by Conorphin-1, a Novel Subtype-Selective Conopeptide, Does Not Mediate Peripheral Analgesia
Publisher: American Chemical Society (ACS)
Date: 12-08-2015
DOI: 10.1021/ACSCHEMNEURO.5B00113
Abstract: Selective activation of peripheral κ opioid receptors (KORs) may overcome the dose-limiting adverse effects of conventional opioid analgesics. We recently developed a vicinal disulfide-stabilized class of peptides with subnanomolar potency at the KOR. The aim of this study was to assess the analgesic effects of one of these peptides, named conorphin-1, in comparison with the prototypical KOR-selective small molecule agonist U-50488, in several rodent pain models. Surprisingly, neither conorphin-1 nor U-50488 were analgesic when delivered peripherally by intraplantar injection at local concentrations expected to fully activate the KOR at cutaneous nerve endings. While U-50488 was analgesic when delivered at high local concentrations, this effect could not be reversed by coadministration with the selective KOR antagonist ML190 or the nonselective opioid antagonist naloxone. Instead, U-50488 likely mediated its peripheral analgesic effect through nonselective inhibition of voltage-gated sodium channels, including peripheral sensory neuron isoforms NaV1.8 and NaV1.7. Our study suggests that targeting the KOR in peripheral sensory nerve endings innervating the skin is not an alternative analgesic approach.
Structure determination of the three disulfide bond isomers of α-conotoxin GI: A model for the role of disulfide bonds in structural stability
Publisher: Elsevier BV
Date: 05-1998
Abstract: The three possible disulfide bonded isomers of alpha-conotoxin GI have been selectively synthesised and their structures determined by 1H NMR spectroscopy. alpha-Conotoxin GI derives from the venom of Conus geographus and is a useful neuropharmacological tool as it selectively binds to the nicotinic acetylcholine receptor (nAChR), a ligand-gated ion channel involved in nerve signal transmission. The peptide has the sequence ECCNPACGRHYSC-NH2, and the three disulfide bonded isomers are referred to as GI(2-7 -13), GI(2-13 -7) and GI(2-3 -13). The NMR structure for the native isomer GI(2-7 -13) is of excellent quality, with a backbone pairwise RMSD of 0.16 A for a family of 35 structures, and comprises primarily a distorted 310 helix between residues 5 to 11. The two non-native isomers exhibit multiple conformers in solution, with the major populated forms being different in structure both from each other and from the native form. Structure-activity relationships for the native GI(2-7 -13) as well as the role of the disulfide bonds on folding and stability of the three isomers are examined. It is concluded that the disulfide bonds in alpha-conotoxin GI play a crucial part in determining both the structure and stability of the peptide. A trend for increased conformational heterogeneity was observed in the order of GI(2-7 -13)<GI(2-13 -7)<GI(2-3 -13). It was found that the peptide bond joining Cys2 to Cys3 in GI(2-3 -13) is predominantly trans, rather than cis as theoretically predicted. These structural data are used to interpret the varying nAChR binding of the non-native forms.A model for the binding of native GI(2-7 -13) to the mammalian nAChR is proposed, with an alpha-subunit binding face made up of Cys2, Asn4, Pro5, Ala6 and Cys7 and a selectivity face, comprised of Arg9 and His10. These two faces orient the molecule between the alpha and delta subunits of the receptor. The structure of the CCNPAC sequence of the native GI(2-7 -13) is compared to the structure of the identical sequence from the toxic domain of heat-stable enterotoxins, which forms part of the receptor binding region of the enterotoxins, but which has a different disulfide connectivity.
Optimized deep-targeted proteotranscriptomic profiling reveals unexplored Conus toxin diversity and novel cysteine frameworks
Publisher: Proceedings of the National Academy of Sciences
Date: 06-07-2015
Abstract: Venomous marine cone snails have evolved complex mixtures of fast-acting paralytic cysteine-rich peptides for prey capture and defense able to modulate specific heterologous membrane receptors, ion channels, or transporters. In contrast to earlier studies in which the richness and sequence hypervariability of lowly expressed toxins were overlooked, we now describe a comprehensive deep-targeted proteotranscriptomic approach that provides, to our knowledge, the first high-definition snapshot of the toxin arsenal of a venomous animal, Conus episcopatus . The thousands of newly identified conotoxins include peptides with cysteine motifs present in FDA-approved molecules or currently undergoing clinical trials. Further highlights include novel cysteine scaffolds likely to unveil unique protein structure and pharmacology, as well as a new category of conotoxins with odd numbers of cysteine residues.
176. Out-of-hospital cardiac arrests in the Gulf region: a scoping review.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2020
Single amino acid substitutions in α-conotoxin PnIA shift selectivity for subtypes of the mammalian neuronal nicotinic acetylcholine receptor
Publisher: Elsevier BV
Date: 12-1999
The role of defensive ecological interactions in the evolution of conotoxins
Publisher: Wiley
Date: 2016
DOI: 10.1111/MEC.13504
Abstract: Venoms comprise of complex mixtures of peptides evolved for predation and defensive purposes. Remarkably, some carnivorous cone snails can inject two distinct venoms in response to predatory or defensive stimuli, providing a unique opportunity to study separately how different ecological pressures contribute to toxin ersification. Here, we report the extraordinary defensive strategy of the Rhizoconus subgenus of cone snails. The defensive venom from this worm-hunting subgenus is unusually simple, almost exclusively composed of αD-conotoxins instead of the ubiquitous αA-conotoxins found in the more complex defensive venom of mollusc- and fish-hunting cone snails. A similarly compartmentalized venom gland as those observed in the other dietary groups facilitates the deployment of this defensive venom. Transcriptomic analysis of a Conus vexillum venom gland revealed the αD-conotoxins as the major transcripts, with lower amounts of 15 known and four new conotoxin superfamilies also detected with likely roles in prey capture. Our phylogenetic and molecular evolution analysis of the αD-conotoxins from five subgenera of cone snails suggests they evolved episodically as part of a defensive strategy in the Rhizoconus subgenus. Thus, our results demonstrate an important role for defence in the evolution of conotoxins.
Solving the α-conotoxin folding problem: Efficient selenium-directed on-resin generation of more potent and stable nicotinic acetylcholine receptor antaqonists
Publisher: American Chemical Society (ACS)
Date: 17-02-2010
DOI: 10.1021/JA910602H
Abstract: Alpha-conotoxins are tightly folded miniproteins that antagonize nicotinic acetylcholine receptors (nAChR) with high specificity for erse subtypes. Here we report the use of selenocysteine in a supported phase method to direct native folding and produce alpha-conotoxins efficiently with improved biophysical properties. By replacing complementary cysteine pairs with selenocysteine pairs on an hiphilic resin, we were able to chemically direct all five structural subclasses of alpha-conotoxins exclusively into their native folds. X-ray analysis at 1.4 A resolution of alpha-selenoconotoxin PnIA confirmed the isosteric character of the diselenide bond and the integrity of the alpha-conotoxin fold. The alpha-selenoconotoxins exhibited similar or improved potency at rat diaphragm muscle and alpha3beta4, alpha7, and alpha1beta1 deltagamma nAChRs expressed in Xenopus oocytes plus improved disulfide bond scrambling stability in plasma. Together, these results underpin the development of more stable and potent nicotinic antagonists suitable for new drug therapies, and highlight the application of selenocysteine technology more broadly to disulfide-bonded peptides and proteins.
Re-engineering the μ-conotoxin SIIIA scaffold
Publisher: Wiley
Date: 23-01-2014
DOI: 10.1002/BIP.22368
Abstract: Voltage-gated sodium (Nav) channels are responsible for generation and propagation of action potentials throughout the nervous system. Their malfunction causes several disorders and chronic conditions including neuropathic pain. Potent subtype specific ligands are essential for deciphering the molecular mechanisms of Nav channel function and development of effective therapeutics. µ-Conotoxin SIIIA is a potent mammalian Nav 1.2 channel blocker that exhibits analgesic activity in rodents. We undertook to reengineer loop 1 through a strategy involving charge alterations and truncations which led to the development of µ-SIIIA mimetics with novel selectivity profiles. A novel [N5K/D15A]SIIIA(3-20) mutant with enhanced net positive charge showed a dramatic increase in its Nav 1.2 potency (IC50 of 0.5 nM vs. 9.6 nM for native SIIIA) though further truncations led to loss of potency. Unexpectedly, it appears that SIIIA loop 1 significantly influences its Nav channel interactions despite loop 2 and 3 residues constituting the pharmacophore. This minimal functional conotoxin scaffold may allow further development of selective NaV blockers.
δ-conotoxin SuVIA suggests an evolutionary link between ancestral predator defence and the origin of fish-hunting behaviour in carnivorous cone snails
Publisher: The Royal Society
Date: 22-07-2015
Abstract: Some venomous cone snails feed on small fishes using an immobilizing combination of synergistic venom peptides that target K v and Na v channels. As part of this envenomation strategy, δ-conotoxins are potent ichtyotoxins that enhance Na v channel function. δ-Conotoxins belong to an ancient and widely distributed gene superfamily, but any evolutionary link from ancestral worm-eating cone snails to modern piscivorous species has not been elucidated. Here, we report the discovery of SuVIA, a potent vertebrate-active δ-conotoxin characterized from a vermivorous cone snail ( Conus suturatus ). SuVIA is equipotent at hNa V 1.3, hNa V 1.4 and hNa V 1.6 with EC 50 s in the low nanomolar range. SuVIA also increased peak hNa V 1.7 current by approximately 75% and shifted the voltage-dependence of activation to more hyperpolarized potentials from –15 mV to –25 mV, with little effect on the voltage-dependence of inactivation. Interestingly, the proximal venom gland expression and pain-inducing effect of SuVIA in mammals suggest that δ-conotoxins in vermivorous cone snails play a defensive role against higher order vertebrates. We propose that δ-conotoxins originally evolved in ancestral vermivorous cones to defend against larger predators including fishes have been repurposed to facilitate a shift to piscivorous behaviour, suggesting an unexpected underlying mechanism for this remarkable evolutionary transition.
Boc SPPS of two hydrophobic peptides using a 'solubilising tail' strategy: Dodecaalanine and chemotactic protein 10 42-55
Publisher: Elsevier BV
Date: 11-1996
The 1.1 Å Resolution crystal structure of [Tyr15]EpI, a novel α- Conotoxin from Conus episcopatus, solved by direct methods
Publisher: American Chemical Society (ACS)
Date: 25-07-1998
DOI: 10.1021/BI9806549
Physico-chemical characterization and synthesis of neuronally active α-conotoxins
Publisher: Wiley
Date: 06-2004
The insecticidal potential of venom peptides
Publisher: Springer Science and Business Media LLC
Date: 23-03-2013
DOI: 10.1007/S00018-013-1315-3
Abstract: Pest insect species are a burden to humans as they destroy crops and serve as vectors for a wide range of diseases including malaria and dengue. Chemical insecticides are currently the dominant approach for combating these pests. However, the de-registration of key classes of chemical insecticides due to their perceived ecological and human health risks in combination with the development of insecticide resistance in many pest insect populations has created an urgent need for improved methods of insect pest control. The venoms of arthropod predators such as spiders and scorpions are a promising source of novel insecticidal peptides that often have different modes of action to extant chemical insecticides. These peptides have been optimized via a prey-predator arms race spanning hundreds of millions of years to target specific types of insect ion channels and receptors. Here we review the current literature on insecticidal venom peptides, with a particular focus on their structural and pharmacological ersity, and discuss their potential for deployment as insecticides.
RegIIA
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.BCP.2011.11.006
Abstract: Neuronal nicotinic acetylcholine receptors (nAChRs) play pivotal roles in the central and peripheral nervous systems. They are implicated in disease states such as Parkinson's disease and schizophrenia, as well as addictive processes for nicotine and other drugs of abuse. Modulation of specific nAChRs is essential to understand their role in the CNS. α-Conotoxins, disulfide-constrained peptides isolated from the venom of cone snails, potently inhibit nAChRs. Their selectivity varies markedly depending upon the specific nAChR subtype/α-conotoxin pair under consideration. Thus, α-conotoxins are excellent probes to evaluate the functional roles of nAChRs subtypes. We isolated an α4/7-conotoxin (RegIIA) from the venom of Conus regius. Its sequence was determined by Edman degradation and confirmed by sequencing the cDNA of the protein precursor. RegIIA was synthesized using solid phase methods and native and synthetic RegIIA were functionally tested using two-electrode voltage cl recording on nAChRs expressed in Xenopus laevis oocytes. RegIIA is among the most potent antagonist of the α3β4 nAChRs found to date and is also active at α3β2 and α7 nAChRs. The 3D structure of RegIIA reveals the typical folding of most α4/7-conotoxins. Thus, while structurally related to other α4/7 conotoxins, RegIIA has an exquisite balance of shape, charge, and polarity exposed in its structure to potently block the α3β4 nAChRs.
Molecular engineering of conotoxins: The importance of loop size to α-conotoxin structure and function
Publisher: American Chemical Society (ACS)
Date: 28-08-2008
DOI: 10.1021/JM800278K
Abstract: Alpha-conotoxins are competitive antagonists of nicotinic acetylcholine receptors (nAChRs). The majority of currently characterized alpha-conotoxins have a 4/7 loop size, and the major features of neuronal alpha-conotoxins include a globular disulfide connectivity and a helical structure centered around the third of their four cysteine residues. In this study, a novel "molecular pruning" approach was undertaken to define the relationship between loop size, structure, and function of alpha-conotoxins. This involved the systematic truncation of the second loop in the alpha-conotoxin [A10L]PnIA [4/7], a potent antagonist of the alpha7 nAChR. The penalty for truncation was found to be decreased conformational stability and increased susceptibility to disulfide bond scrambling. Truncation down to 4/4[A10L]PnIA maintained helicity and did not significantly reduce electrophysiological activity at alpha7 nAChRs, whereas 4/3[A10L]PnIA lost both alpha7 nAChR activity and helicity. In contrast, all truncated analogues lost approximately 100-fold affinity at the AChBP, a model protein for the extracellular domain of the nAChR. Docking simulations identified several hydrogen bonds lost upon truncation that provide an explanation for the reduced affinities observed at the alpha7 nAChR and AChBP.
In situ neutralization in Boc‐chemistry solid phase peptide synthesis: Rapid, high yield assembly of difficult sequences
Publisher: Wiley
Date: 09-1992
DOI: 10.1111/J.1399-3011.1992.TB00291.X
Abstract: Simple, effective protocols have been developed for manual and machine‐assisted Boc‐chemistry solid phase peptide synthesis on polystyrene resins. These use in situ neutralization [i.e. neutralization simultaneous with coupling], high concentrations ( 0.2 M) of Boc‐amino acid‐OBt esters plus base for rapid coupling, 100% TFA for rapid Boc group removal, and a single short (30 s) DMF flow wash between deprotection/coupling and between coupling/deprotection. Single 10 min coupling times were used throughout. Overall cycle times were 15 min for manual and 19 min for machine‐assisted synthesis (75 residues per day). No racemization was detected in the base‐catalyzed coupling step. Several side reactions were studied, and eliminated. These included: pyrrolidonecarboxylic acid formation from Gln in hot TFA‐DMF chain‐termination by reaction with excess HBTU and, chain termination by acetylation (from HOAc in commercial Boc‐amino acids). The in situ neutralization protocols gave a significant increase in the efficiency of chain assembly, especially for “difficult” sequences arising from sequence‐dependent peptide chain aggregation in standard (neutralization prior to coupling) Boc‐chemistry SPPS protocols or in Fmoc‐chemistry SPPS. Reported syntheses include HIV‐1 protease(1–50,Cys.amide), HIV‐1 protease(53–99), and the full length HIV‐1 protease(1–99).
Development of a μO-conotoxin analogue with improved lipid membrane interactions and potency for the analgesic sodium channel NaV 1.8
Publisher: Elsevier BV
Date: 05-2016
Conformational constraints: Nonpeptide β‐turn mimics
Publisher: Wiley
Date: 04-1990
Abstract: The beta-turn, which has also been referred to as the beta-bend, beta-loop or reverse turn, has been implicated as an important site for molecular recognition in many biologically active peptides and in globular proteins. This small secondary structure therefore makes an attractive target for mimicry by a conformational constraint, because a peptide which is constrained in a biologically active conformation can display a number of advantages over the parent substrate. The less peptide-like such a constraint is, the more potential there is to maximize these advantages. A decade has passed since the first (and highly successful) attempt to mimic the beta-turn with a nonpeptide conformational constraint was disclosed by Freidinger et al. (1980). Since this report, rapidly growing interest in the field of nonpeptide beta-turn mimics has seen a variety of experimental approaches and a mixed bag of results. It is attempted in this review, not only to summarize and critically analyse these approaches, but also to touch on the complexities associated with the conformational mimicry of such a erse structure as the beta-turn.
Ancient Venom Systems: A Review on Cnidaria Toxins
Publisher: MDPI AG
Date: 18-06-2015
Novel analgesic ω-conotoxins from the vermivorous cone snail Conus moncuri provide new insights into the evolution of conopeptides
Publisher: Springer Science and Business Media LLC
Date: 07-09-2018
DOI: 10.1038/S41598-018-31245-4
Abstract: Cone snails are a erse group of predatory marine invertebrates that deploy remarkably complex venoms to rapidly paralyse worm, mollusc or fish prey. ω-Conotoxins are neurotoxic peptides from cone snail venoms that inhibit Ca v 2.2 voltage-gated calcium channel, demonstrating potential for pain management via intrathecal (IT) administration. Here, we isolated and characterized two novel ω-conotoxins, MoVIA and MoVIB from Conus moncuri , the first to be identified in vermivorous (worm-hunting) cone snails. MoVIA and MoVIB potently inhibited human Ca v 2.2 in fluorimetric assays and rat Ca v 2.2 in patch cl studies, and both potently displaced radiolabeled ω-conotoxin GVIA ( 125 I-GVIA) from human SH-SY5Y cells and fish brain membranes (IC 50 2–9 pM). Intriguingly, an arginine at position 13 in MoVIA and MoVIB replaced the functionally critical tyrosine found in piscivorous ω-conotoxins. To investigate its role, we synthesized MoVIB-[R13Y] and MVIIA-[Y13R]. Interestingly, MVIIA-[Y13R] completely lost Ca v 2.2 activity and MoVIB-[R13Y] had reduced activity, indicating that Arg at position 13 was preferred in these vermivorous ω-conotoxins whereas tyrosine 13 is preferred in piscivorous ω-conotoxins. MoVIB reversed pain behavior in a rat neuropathic pain model, confirming that vermivorous cone snails are a new source of analgesic ω-conotoxins. Given vermivorous cone snails are ancestral to piscivorous species, our findings support the repurposing of defensive venom peptides in the evolution of piscivorous Conidae .
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