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CgNa (Condylactis gigantea neurotoxin) is a 47-amino-acid- residue toxin from the giant Caribbean sea anemone Condylactis gigantea. The structure of CgNa, which was solved by 1H-NMR spectroscopy, is somewhat atypical and displays significant homology with both type I and II anemone toxins. CgNa also displays a considerable number of exceptions to t...
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We have characterized the effects of BgII and BgIII, two sea anemone peptides with almost identical sequences (they only differ by a single amino acid), on neuronal sodium currents using the whole-cell patch-clamp technique. Neurons of dorsal root ganglia of Wistar rats (P5-9) in primary culture (Leibovitz's L15 medium; 37 degrees C, 95% air/5% CO2...
We have characterized the actions of ApC, a sea anemone polypeptide toxin isolated from Anthopleura elegantissima, on neuronal sodium currents (I(Na)) using current and voltage-clamp techniques. Neurons of the dorsal root ganglia of Wistar rats (P5-9) in primary culture were used for this study. These cells express tetrodotoxin-sensitive (TTX-S) an...
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... However, β-defensin-like peptides in sea anemone venom including CgNa, Rc I, Am II, BDS I, APETx1, APETx2, and Magnificamide are potential toxins that may disrupt voltage-and ligandgated ion channels as Nav types 1/2/4, Kv type 3, ASIC, and ASIC3 [54][55][56][57][58][59][60] . CgNa can be purified from the sea anemone Condylactis gigantea and inhibit Nav types 1/2 61 . Rc I is a peptide toxin in H. crispa, which can inhibit Nav channels 62 . ...
Peptide toxins found in sea anemones venom have diverse properties that make them important research subjects in the fields of pharmacology, neuroscience and biotechnology. This study used high-throughput sequencing technology to systematically analyze the venom components of the tentacles, column, and mesenterial filaments of sea anemone Heteractis crispa, revealing the diversity and complexity of sea anemone toxins in different tissues. A total of 1049 transcripts were identified and categorized into 60 families, of which 91.0% were proteins and 9.0% were peptides. Of those 1049 transcripts, 416, 291, and 307 putative proteins and peptide precursors were identified from tentacles, column, and mesenterial filaments respectively, while 428 were identified when the datasets were combined. Of these putative toxin sequences, 42 were detected in all three tissues, including 33 proteins and 9 peptides, with the majority of peptides being ShKT domain, β-defensin, and Kunitz-type. In addition, this study applied bioinformatics approaches to predict the family classification, 3D structures, and functional annotation of these representative peptides, as well as the evolutionary relationships between peptides, laying the foundation for the next step of peptide pharmacological activity research.
... The solvent-free crude extract was triturated in MeOH. The MeOH soluble portion (A1, 44.5 g) was fractionated on a column of Sephadex LH-20 eluted with MeOH (6 L) to yield three fractions A11 (orange semisolid residue, 19.0 g), A12 (reddish gummy residue, 24.5 g), and A13 (green solid mass, 0.9 g). Fraction A12, which exhibited an in vitro cytotoxicity, was chromatographed on a column of Si gel 60 using EtOAc-n-hexane (stepwise, 7.5-100% EtOAc) followed by MeOH-EtOAc (stepwise, 10-50% MeOH) to afford 24 subfractions A1201 to A1225. ...
The Condylactis-genus anemones were examined for their proteinaceous poisons over 50 years ago. On the other hand, the current research focuses on isolating and describing the non-proteinaceous secondary metabolites from the invasive Condylactis anemones, which help take advantage of their population outbreak as a new source of chemical candidates and potential drug leads. From an organic extract of Condylactis sp., a 1,2,4-thiadiazole-based alkaloid, identified as 3,5-bis(3-pyridinyl)-1,2,4-thiadiazole (1), was found to be a new natural alkaloid despite being previously synthesized. The full assignment of NMR data of compound 1, based on the analysis of 2D NMR correlations, is reported herein for the first time. The proposed biosynthetic precursor thionicotinamide (2) was also isolated for the first time from nature along with nicotinamide (3), uridine (5), hypoxanthine (6), and four 5,8-epidioxysteroids (7–10). A major secondary metabolite (−)-betonicine (4) was isolated from Condylactis sp. and found for the first time in marine invertebrates. The four 5,8-epidioxysteroids, among other metabolites, exhibited cytotoxicity (IC50 3.5–9.0 μg/mL) toward five cancer cell lines.
... Gene cloning, which became a traditional method of studying sea anemone neurotoxins by the end of the last century, made it possible to detect up to a dozen or even more highly homologous amino acid sequences in each of the studied species, which significantly expanded the arsenal of neurotoxins for further structural and functional studies [5,14,16,39]. The majority of the studied sea anemone neurotoxins to date belong to the most common structural type 1: ATX-Ia, -II, -V from Anemonia sulcata [21][22][23][24]26,82,[93][94][95][96][97][98], ApA and ApB from Anthopleura xanthogrammica [25,30,99], Am-III from Antheopsis maculata [100], Rc-1 from Radianthus crispus [101], CgNa from Condylactis gigantea [102], Gigantoxin-2 from Stichodactyla gigantea [103], BcIII from Bunodosoma caissarum [104], BgII, BgIII from Bunodosoma granulifera [105], and cangitoxins from Bunodosoma cangicum [106][107][108]. [85,102] from C. gigantea; Cp1 (P0CH42) and Cp2 (P0C280) [32] from Condylactis passiflora; Gigantoxin-2 (Q76CA3) [103] from S. gigantea; AETX-1 (P69943) [34] from Anemonia erythraea; ATX-Ia (=ATX-I) (P01533) [96], ATX-Ib (A0A0S1M165), ATX-II (P01528) [23], ATX-V (P01529) [97] from A. sulcata; Av2 (P0DL52) [95,98] from Anemonia viridis (previously known as A. sulcata) and Av6, Av9 (sequences, deduced from A. viridis genomic DNA [95]; BcIII (Q7M425) [104] from B. caissarum; BgII (P0C1F4), BgIII (P0C1F5) [105] from B. granulifera; CGTX (P82803), CGTX-II (P0C7P9), CGTX-III (P0C7Q0) [106], Bcg1a (P86459), Bcg1b (P86460) [107,108] from B. cangicum; APE1-1 (P0C1F0), APE1-2 (P0C1F1) [109], APE2-1 (=ApC) (P01532) [110], APE2-2 (P0C1F3) [109] from Anthopleura elegantissima; Hk2a (P0C5F4), Hk7a (P0C5F5), Hk8a (P0C5F6), Hk16a (P0C5F7) [111] from Anthopleura sp.; AFT-I (P10453), AFT-II (P10454) from Anthopleura fuscoviridis [112]; Bca1a (GenBank accession number: KY789430) [113] from Bunodosoma capense; AdE-1 (E3P6S4) [114] from Aiptasia diaphana; Ae1 (=Ae1-1) (Q9NJQ2) [33] from A. equina, Ae2-1 (B1NWU2), Ae2-2 (B1NWU3), Ae2-3 (B1NWU4), Ae3-1 (B1NWU5), and Ae4-1 (B1NWU6) derived from A. equina genomic DNA [95]. ...
... The majority of the studied sea anemone neurotoxins to date belong to the most common structural type 1: ATX-Ia, -II, -V from Anemonia sulcata [21][22][23][24]26,82,[93][94][95][96][97][98], ApA and ApB from Anthopleura xanthogrammica [25,30,99], Am-III from Antheopsis maculata [100], Rc-1 from Radianthus crispus [101], CgNa from Condylactis gigantea [102], Gigantoxin-2 from Stichodactyla gigantea [103], BcIII from Bunodosoma caissarum [104], BgII, BgIII from Bunodosoma granulifera [105], and cangitoxins from Bunodosoma cangicum [106][107][108]. [85,102] from C. gigantea; Cp1 (P0CH42) and Cp2 (P0C280) [32] from Condylactis passiflora; Gigantoxin-2 (Q76CA3) [103] from S. gigantea; AETX-1 (P69943) [34] from Anemonia erythraea; ATX-Ia (=ATX-I) (P01533) [96], ATX-Ib (A0A0S1M165), ATX-II (P01528) [23], ATX-V (P01529) [97] from A. sulcata; Av2 (P0DL52) [95,98] from Anemonia viridis (previously known as A. sulcata) and Av6, Av9 (sequences, deduced from A. viridis genomic DNA [95]; BcIII (Q7M425) [104] from B. caissarum; BgII (P0C1F4), BgIII (P0C1F5) [105] from B. granulifera; CGTX (P82803), CGTX-II (P0C7P9), CGTX-III (P0C7Q0) [106], Bcg1a (P86459), Bcg1b (P86460) [107,108] from B. cangicum; APE1-1 (P0C1F0), APE1-2 (P0C1F1) [109], APE2-1 (=ApC) (P01532) [110], APE2-2 (P0C1F3) [109] from Anthopleura elegantissima; Hk2a (P0C5F4), Hk7a (P0C5F5), Hk8a (P0C5F6), Hk16a (P0C5F7) [111] from Anthopleura sp.; AFT-I (P10453), AFT-II (P10454) from Anthopleura fuscoviridis [112]; Bca1a (GenBank accession number: KY789430) [113] from Bunodosoma capense; AdE-1 (E3P6S4) [114] from Aiptasia diaphana; Ae1 (=Ae1-1) (Q9NJQ2) [33] from A. equina, Ae2-1 (B1NWU2), Ae2-2 (B1NWU3), Ae2-3 (B1NWU4), Ae3-1 (B1NWU5), and Ae4-1 (B1NWU6) derived from A. equina genomic DNA [95]. The disulfide bridges are shown above the alignment. ...
... Am-III (P69928) [100] from A. maculata; Rc-1 (P0C5G5) [101] from Heteractis crispa (=R. crispus); CgNa (P0C280) [85,102] from C. gigantea; Cp1 (P0CH42) and Cp2 (P0C280) [32] from Condylactis passiflora; Gigantoxin-2 (Q76CA3) [103] from S. gigantea; AETX-1 (P69943) [34] from Anemonia erythraea; ATX-Ia (=ATX-I) (P01533) [96], ATX-Ib (A0A0S1M165), ATX-II (P01528) [23], ATX-V (P01529) [97] from A. sulcata; Av2 (P0DL52) [95,98] from Anemonia viridis (previously known as A. sulcata) and Av6, Av9 (sequences, deduced from A. viridis genomic DNA [95]; BcIII (Q7M425) [104] from B. caissarum; BgII (P0C1F4), BgIII (P0C1F5) [105] from B. granulifera; СGTX (P82803), СGTX-II (P0C7P9), СGTX-III (P0C7Q0) [106], Bcg1a (P86459), Bcg1b (P86460) [107,108] from B. cangicum; APE1-1 (P0C1F0), APE1-2 (P0C1F1) [109], APE2-1 (=ApC) (P01532) [110], APE2-2 (P0C1F3) [109] from Anthopleura elegantissima; Hk2a (P0C5F4), Hk7a (P0C5F5), Hk8a (P0C5F6), Hk16a (P0C5F7) [111] from Anthopleura sp.; AFT-I (P10453), AFT-II (P10454) from Anthopleura fuscoviridis [112]; Bca1a (GenBank accession number: KY789430) [113] from Bunodosoma capense; AdE-1 (E3P6S4) [114] from Aiptasia diaphana; Ae1 (=Ae1-1) (Q9NJQ2) [33] from A. equina, Ae2-1 (B1NWU2), Ae2-2 (B1NWU3), Ae2-3 (B1NWU4), Ae3-1 (B1NWU5), and Ae4-1 (B1NWU6) derived from A. equina genomic DNA [95]. The disulfide bridges are shown above the alignment. ...
Many human cardiovascular and neurological disorders (such as ischemia, epileptic seizures, traumatic brain injury, neuropathic pain, etc.) are associated with the abnormal functional activity of voltage-gated sodium channels (VGSCs/NaVs). Many natural toxins, including the sea anemone toxins (called neurotoxins), are an indispensable and promising tool in pharmacological researches. They have widely been carried out over the past three decades, in particular, in establishing different NaV subtypes functional properties and a specific role in various pathologies. Therefore, a large number of publications are currently dedicated to the search and study of the structure-functional relationships of new sea anemone natural neurotoxins–potential pharmacologically active compounds that specifically interact with various subtypes of voltage gated sodium channels as drug discovery targets. This review presents and summarizes some updated data on the structure-functional relationships of known sea anemone neurotoxins belonging to four structural types. The review also emphasizes the study of type 2 neurotoxins, produced by the tropical sea anemone Heteractis crispa, five structurally homologous and one unique double-stranded peptide that, due to the absence of a functionally significant Arg14 residue, loses toxicity but retains the ability to modulate several VGSCs subtypes.
... Some-such as AFT-II from Anthopleura fuscoviridis, ApC from Anthopleura elegantissima, Bc-III from Bunodosoma caissarum, CGTX-II from Bunodosoma cangicum, CgNa from Condylactis gigantea, or RTX-III from Heteractis crispa-exhibit selectivity for specific Na V isoforms. 64,96,[107][108][109]120,142 In addition, phospholipase-A 2 is found in venoms across all cnidarian classes, as are pore-forming toxins. 92 However, the contribution of these toxins to pain and nociception has not been explored systematically, in part because many jellyfish venoms in particular suffer from poor stability and venom extraction is, compared with other venomous animals, somewhat more difficult. ...
... CgNa was purified from Condylactis gigantea, sea anemone. It inhibits Nav types I and II (Salceda et al., 2007). Five homologous sequences with sea anemone toxin APETx1 and CgNa were identified, and their cysteine pattern was CXC-C-C-CC ( Figure 7A). ...
Sea anemone venom is a marine drug resource library with pharmacological and biotechnology value, and it contains complex and diverse functional peptide neurotoxins. However, the venom components of only a limited number of sea anemone species have been globally evaluated by transcriptomics and proteomics. In this study, 533 putative protein as well as peptide toxin sequences were found on a large scale from dissimilar developmental stages of sea anemone Exaiptasia diaphana, which can be divided into 75 known superfamilies according to the predicted functions. Among them, the proportion of protein is 72.98%, and its main families are metalloproteases, chymotrypsinogen like, collagen, pancreatic lipase-associated protein like, and G-protein coupled receptor, while the proportion of peptides is 27.02%, and main families are ShK domain, thrombin, Kunitz-type, defensin, as well as insulin-like peptide. Finally, typical anemone peptide neurotoxins were screened, and the 3D structure and pharmacological activity of these anemone peptide neurotoxins were predicted by homology modeling. We elucidate on a valuable high-throughput approach for obtaining sea anemone proteins and peptides. Our findings form the basis for targeted studies on the diversity as well as pharmacological effects of sea anemone peptide neurotoxins.
... The threedimensional structures of sea anemone peptide toxins determined by Solution NMR are summarized in Table 5 (Ref. [20,22,29,30,167,[173][174][175][176][177][178][179][180][181][182][183]). ...
As primitive metazoa, sea anemones are rich in various bioactive peptide neurotoxins. These peptides have been applied to neuroscience research tools or directly developed as marine drugs. To date, more than 1100 species of sea anemones have been reported, but only 5% of the species have been used to isolate and identify sea anemone peptide neurotoxins. There is an urgent need for more systematic discovery and study of peptide neurotoxins in sea anemones. In this review, we have gathered the currently available methods from crude venom purification and gene cloning to venom multiomics, employing these techniques for discovering novel sea anemone peptide neurotoxins. In addition, the three-dimensional structures and targets of sea anemone peptide neurotoxins are summarized. Therefore, the purpose of this review is to provide a reference for the discovery, development, and utilization of sea anemone peptide neurotoxins.
... Thus far, many toxins derived from sea anemones have been discovered and categorized under the 3 types: type I sea anemone toxins (Av2-like toxins); type II sea anemone toxins (Rp3-like toxins); and type III, which includes Av3 and Ea1 [115,[117][118][119]. Toxins that belong to type I are powerful modulators of NaV channels that bind to site 3 at domain IV of the channel [120]. ...
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.
... In general, the CD spectra of δ-SHTX-Hcr1f, RTX-III, and RTX-VI indicated a predominant content of β-strands. According to the NMR data, there are no α-helices in the spatial structure of the previously investigated toxins of types I and II: ApA (PDB ID: 1Ahl) [28], ApB (1Apf) [29], As1 (1Atx) [30], CgNa (2H9x) [31], and ShI (1Shi, 1Sh1, and 2Sh1) [32]. CD spectroscopy of δ-SHTX-Hcr1f, RTX-III, and RTX-VI toxins showed α-helices to be practically absent in their structure (there is 5% of α-helix in δ-SHTX-Hcr1f structure), in accordance with the literature data. ...
... The unique natural analogue of RTX-III, the toxin RTX-VI, consists of two peptide chains (12 and 35 aa) connected by two disulfide bonds (C3-C43 and C5-C33); the third disulfide bond is formed within chain 2 (C26-C44). Deletion of Arg13 in RTX-VI does not lead to significant changes in its secondary structure, characteristic for the type I and II toxins [31]. RTX-VI appears to be the result of a previously undescribed post-translational modification that occurs in the sea anemone rather than during isolation of the peptide. ...
Toxins modulating NaV channels are the most abundant and studied peptide components of sea anemone venom. Three type-II toxins, δ-SHTX-Hcr1f (= RpII), RTX-III, and RTX-VI, were isolated from the sea anemone Heteractis crispa. RTX-VI has been found to be an unusual analog of RTX-III. The electrophysiological effects of Heteractis toxins on nine NaV subtypes were investigated for the first time. Heteractis toxins mainly affect the inactivation of the mammalian NaV channels expressed in the central nervous system (NaV1.1–NaV1.3, NaV1.6) as well as insect and arachnid channels (BgNaV1, VdNaV1). The absence of Arg13 in the RTX-VI structure does not prevent toxin binding with the channel but it has changed its pharmacological profile and potency. According to computer modeling data, the δ-SHTX-Hcr1f binds within the extracellular region of the rNaV1.2 voltage-sensing domain IV and pore-forming domain I through a network of strong interactions, and an additional fixation of the toxin at the channel binding site is carried out through the phospholipid environment. Our data suggest that Heteractis toxins could be used as molecular tools for NaV channel studies or insecticides rather than as pharmacological agents.
... The most studied type of the sea anemone ion channel-targeting ligands has been shown by today to belong to sodium channel type I and II neurotoxins (46-48 aa, respectively) (Figure 1a), which are highly potent modulators of different mammalian Na V subtypes [14]. Their functionally active Arg-loop (Figure 1b) interacts specif- ...
... Moreover, because certain toxins from Halcurias sp., Nematostella vectensis and Condylactis gigantean resemble both type 1 and 2 sequences [112,113], Moran and co-workers [88] have suggested that this classification should be revaluated ( Figure 5). The 3D structures of both type 1 and 2 consist of an antiparallel β-sheet composed of four β-strands and a highly flexible loop, which has been named the 'Arg14 loop', because Arg14 is the most conserved residue ( Figure 5) [114][115][116][117][118]. Site-directed mutagenesis of AP-B (-actitoxin-Axm1b) revealed that the flexibility of this loop is important for the selectivity and binding of these toxins to NaV channels. ...
... Figure modified with permission from Biochemical Journal; published by Portland Press, 2007[118]. ...
Sea anemones produce venoms of exceptional molecular diversity, with at least 17 different molecular scaffolds reported to date. These venom components have traditionally been classified according to pharmacological activity and amino acid sequence. However, this classification system suffers from vulnerabilities due to functional convergence and functional promiscuity. Furthermore, for most known sea anemone toxins, the exact receptors they target are either unknown, or at best incomplete. In this review, we first provide an overview of the sea anemone venom system and then focus on the venom components. We have organised the venom components by distinguishing firstly between proteins and non-proteinaceous compounds, secondly between enzymes and other proteins without enzymatic activity, then according to the structural scaffold, and finally according to molecular target.
