Structure and Function of Proteinaceous Toxins from Marine Animals

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Two liable potent hemolytic toxins from the tentacles of the stinging box jellyfish (sea wasp) Carybdea rastoni were isolated and sequenced, C. rastoni toxin-A and -B (CrTX-A and -B). CrTX-A and -B which have molecular masses of 43 and 46 kDa (calculated from (SDS-PAGE), respectively. The full-length cDNA (1600bp) which encodes CrTXs was sequenced. The deduced amino acid sequence of CrTXs, composed of 450 amino acids, showed no significant homology with any known protein. This is the first complete sequence of a jellyfish proteinous toxin to be reported. The experimental results showed CrTX-A was a toxin responsible for the cutaneous inflammation observed in humans inflicted by C. rastoni's sting. The box jellyfish (Sea Wasp) Carybdea alata (Cubozoa) is distributed widely in the tropics. We successfully isolated C. alata toxin-A (CaTX-A, 43kDa) and -B (CaTX-B, 45kDa) for the first time from the tentacle of C. alata collected at the Hawaiian shore. Furthermore, we sequenced the cDNA enc … More oding CaTX-A. We successftlly isolated Chiropsalmus quadrigatus toxin-A (CqTX-A, 44 kDa), a major proteinaceous toxin, for the frst time, from the deadly box jellyfish C. quadrigatus. We sequenced the cDNA encoding CqTX-A. The deduced amino acid sequence of CqTX-A (462 amino acids) showed 25.2% and 21.6% sequence similarity to Carybdea rastoni toxins (CrTXs) and Carybdea alata toxin-A (CrTX-A). The box jellyfish toxins represent a novel bioactive protein family.The Okinawan sea anemone Phyllodiscus semoni is known to cause cases of severe stinging. We isolated Phyllodiscus semoni toxin 20A (PsTX-20A), a hemolytic and lethal polypeptide (20 kDa), from this species for the first time as a minor toxin. Furthermore, we sequenced the cDNA encoding PsTX-20A. The deduced amino acid sequence of PsTX-20A showed that this toxin was a new member of the actinoporin family, which consists of several cytolytic polypeptides originating from sea anemones. We isolated Phyllodiscus semoni toxins 60A and 60B (PsTX-60A and PsTX-60B ; ca. 60 kDa) as the major toxins of this species. We sequenced the cDNA encoding PsTX-60A. We also isolated Actineria villosa toxin 60A (AvTX-60A, 60 kDa) as the major toxin from this venomous sea anemone. Furthermore, the cDNA encoding AvTX-60A was sequenced. The deduced amino acid sequence of AvTX-60A showed similarity with PsTX-60A. It was demonstrated that these sea anemone toxins were new members of a membrane-attack complex/ perforin (MACPF) family. These are the first examples of MACPF type proteins as the toxins for prey acquisition or repelling predators in nature.Our study showed the venomous cnidarians are rich sources of novel bioactive proteins. Further chemical and pharmacological study on the cnidarian toxins will lead to discover new tools for bio-medical study, proteinaceous drugs which have new mode of action, and develop of new remedy methods for these animal's stinging cases. Less