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Review
. 2012 Aug;10(8):1812-1851.
doi: 10.3390/md10081812. Epub 2012 Aug 22.

Sea anemone (Cnidaria, Anthozoa, Actiniaria) toxins: an overview

Bárbara Frazão  1   2 , Vitor Vasconcelos  1   2 , Agostinho Antunes  1   2
Affiliations
Review

Sea anemone (Cnidaria, Anthozoa, Actiniaria) toxins: an overview

Bárbara Frazão et al. Mar Drugs. 2012 Aug.

Abstract

The Cnidaria phylum includes organisms that are among the most venomous animals. The Anthozoa class includes sea anemones, hard corals, soft corals and sea pens. The composition of cnidarian venoms is not known in detail, but they appear to contain a variety of compounds. Currently around 250 of those compounds have been identified (peptides, proteins, enzymes and proteinase inhibitors) and non-proteinaceous substances (purines, quaternary ammonium compounds, biogenic amines and betaines), but very few genes encoding toxins were described and only a few related protein three-dimensional structures are available. Toxins are used for prey acquisition, but also to deter potential predators (with neurotoxicity and cardiotoxicity effects) and even to fight territorial disputes. Cnidaria toxins have been identified on the nematocysts located on the tentacles, acrorhagi and acontia, and in the mucous coat that covers the animal body. Sea anemone toxins comprise mainly proteins and peptides that are cytolytic or neurotoxic with its potency varying with the structure and site of action and are efficient in targeting different animals, such as insects, crustaceans and vertebrates. Sea anemones toxins include voltage-gated Na⁺ and K⁺ channels toxins, acid-sensing ion channel toxins, Cytolysins, toxins with Kunitz-type protease inhibitors activity and toxins with Phospholipase A2 activity. In this review we assessed the phylogentic relationships of sea anemone toxins, characterized such toxins, the genes encoding them and the toxins three-dimensional structures, further providing a state-of-the-art description of the procedures involved in the isolation and purification of bioactive toxins.

Keywords: Cnidaria; phylogeny; sea anemone; toxin; toxin gene.

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Figures

Figure 1
Figure 1
Simplified cladogram of the phylum Cnidaria (adapted from [3]). Photos a, e and f were retrieved from [4].
Figure 2
Figure 2
Schematic representation of a typical life cycle of an Anthozoa.
Figure 3
Figure 3
General aspects of the sea anemone morphology. (a) Acrorhagi, the blue vesicles in Actinia equina, green variety (also called Actinia prasina), are used to fight against space towards other individuals (see arrow); (b) Acontia, the white threads secreted by Calliactis parasitica are used as defensive organs when disturbed (see arrow); (c) Bunodactis verrucosa specimens with tentacles retracted and fully expanded, illustrating the characteristic column with adhesive verrucae and short tentacles.
Figure 4
Figure 4
Maximum likelihood tree of Cytolysins with 100 bootstrap replicates (only bootstrap values > 50 are shown). I—proteins without the MACPF domain, II—proteins with the MACPF domain, III—toxins from Actiniidae family members, IV—toxins from Stichodactilidae family members and Oulactis orientalis (Actiniidae ), V—toxins from Sagartiidae and and Alisiidae family members. Toxins are also referred on the Cytolysins chapter.
Figure 5
Figure 5
Number of publications from 1961 to date on cnidarians toxins (retrieved from the Pubmed in May 2012).
Figure 6
Figure 6
Ribbon view of Equinatoxin-II (a) and Sticholysin II(b), showing their secondary structure. α-helices, in pink, and β-sandwiches, in yellow.
Figure 7
Figure 7
Ribbon view of ATX-III. A peptide toxin from Anemonia viridis that interacts with NaV channels. It does not contain α-helixes or β-sheets.
Figure 8
Figure 8
Ribbon structures of BgK(a) and ChTx toxins(b). BgK lacks the β-sheet secondary structure, while ChTx and most of the scorpion toxins have β-sheet at both ends of the molecule. Also, the molecular scaffolds for the KV channel-binding surfaces of each toxin are of different type: helix (in pink) for BgK and β-sheet (in yellow) for ChTx [153].
Figure 9
Figure 9
View in tube style of BgK in blue (a) and ChTx in red (b) molecules, with the residues Lys25/Tyr26/Phe6 in green and Lys27/Tyr36in pink, respectively. Superimposition of the functional dyad Lys27/Tyr36 (in pink) from ChTx with the functional dyad of BgK Lys25/Tyr26 in (c) and with the functional dyad Lys25/Phe6 in (d) (adapted from [152]).
Figure 10
Figure 10
Solvent-accessibility surface representations of Anthopleurin-B (a), CgNa (b) and Sh1 (c), evidencing the electrostatic potential at the surface of the molecule. The color blue represents highly positive and red, highly negative, in grade (adapted from [154]).
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References

    1. Technau U., Steele R.E. Evolutionary crossroads in developmental biology: Cnidaria. Development. 2011;138:1447–1458. doi: 10.1242/dev.048959. - DOI - PMC - PubMed
    1. Turk T., Kem W.R. The phylum Cnidaria and investigations of its toxins and venoms until 1990. Toxicon. 2009;54:1031–1037. doi: 10.1016/j.toxicon.2009.06.031. - DOI - PubMed
    1. Collins A.G. Recent insights into cnidarian phylogeny. Smithsonian Contrib. Mar. Sci. 2009;38:139–149.
    1. Wikimedia commons. [(acessed on 27 February 2012)]. Available online: http://commons.wikimedia.org/wiki/
    1. Nevalainen T.J., Peuravuori H.J., Quinn R.J., Llewellyn L.E., Benzie J.A., Fenner P.J., Winkel K.D. Phospholipase A2 in cnidaria. Comp. Biochem. Physiol. Part B. 2004;139:731–735. doi: 10.1016/j.cbpc.2004.09.006. - DOI - PubMed

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