Sea Anemone (Cnidaria, Anthozoa, Actiniaria) Toxins: An Overview

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.

BcsTx3 is a founder of a novel sea anemone toxin family of potassium channel blocker

“…They contain a variety of toxic proteins and peptides, including potent toxins affecting the transient receptor protein vanilloid (TRPV1), acid-sensing ion channels, voltage-gated Na + (Na V ) and K + channels, as well as secondary metabolites [4]. Recently, the ectodermal gland cells were also reported as a toxin production compartment in sea anemones [5].…”

“…and Shaw (K V 3.) subfamilies and also intermediate conductance calcium-activated K + channels [4]. Potassium channel toxins of this type have been characterized from the venom of sea anemones of different families (Actiniidae, Hormathiidae, Stichodactylidae and Thalassianthidae) and can be subdivided into subtype 1a and subtype 1b, having four and eight amino acid residues respectively between the second and third cysteine residues [8,9].…”

Potential environmental risks associated with biofouling management in salmon aquaculture

“…Like all cnidarians, hydroids and anemones possess millions of harpoon-like stinging cells (nematocysts) that contain nerve-or cardiotoxins and are used to capture and immobilise prey (Sher & Zlotkin 2009, Frazão et al 2012, Cegolon et al 2013). Hydroids and anemones are relatives of the hydrozoan and scyphozoan jellyfish that have been identified as important agents of gill disorder in farmed salmon .…”

Discoveries of Serine Protease Inhibitors from Scorpions

“…Among all classes, the Kunitz-type inhibitors are well characterized of them, possibly due to their abundance in several creatures [13,15,16]. Many studies reported that animal venoms contain Kunitz-type serine protease inhibitors [12,[17][18][19]. Similarly, Kunitz-type as well as Ascaris-type serine protease inhibitors have been reported to be present in scorpions, and most of them have been identified by cDNA cloning and transcriptomic analysis [10,11,[20][21][22].…”