Watkins Maren, Hillyard David R, Olivera Baldomero M
Department of Pathology, University of Utah, Salt Lake City, 84112, USA.
J Mol Evol. 2006 Mar;62(3):247-56. doi: 10.1007/s00239-005-0010-x. Epub 2006 Feb 13.
The toxoglossate mollusks are a large group of venomous animals (>10,000 species) conventionally divided into three groups, the cone snails, the auger snails, and the turrid snails; turrids account for >90% of the biodiversity of toxoglossans. Only the venoms of cone snails have been intensively investigated, with little work focused on turrids. We report the first broad characterization of genes expressed in venom ducts of any turrid species. Twenty-three different cDNA clones encoding putative toxins were characterized from the venom duct of the turrine species Lophiotoma olangoensis Olivera 2002 and belong to 16 different gene families. Of the 16 different Lophiotoma olangoensis gene families that encode putative toxins, for only 1 was there clear evidence of sequence similarity with any conotoxin gene family. The I-like gene family of Lophiotoma olangoensis was found to be related to the K channel-targeted I(2) conotoxin superfamily. Most putative Lophiotoma toxins are cysteine-rich polypeptides, with a significant fraction much larger (>80 amino acids) than the toxins from cone snails. A small number were not cysteine-rich but had hydrophobic amino acid clusters interspersed with arginine residues. This is only 1 of >10,000 different turrid venoms that needs to be characterized. From this study, a common origin with Conus for one family of putative turrid toxins is indicated.
毒舌软体动物是一大类有毒动物（超过10000种），传统上分为三组：芋螺、钻螺和塔螺；塔螺占毒舌动物生物多样性的90%以上。目前仅对芋螺的毒液进行了深入研究，而针对塔螺的研究较少。我们首次对任何塔螺物种毒腺中表达的基因进行了广泛表征。从2002年Olivera鉴定的塔螺物种奥兰戈冠螺的毒腺中鉴定出23个编码假定毒素的不同cDNA克隆，它们属于16个不同的基因家族。在这16个编码假定毒素的奥兰戈冠螺不同基因家族中，只有1个与任何芋螺毒素基因家族有明显的序列相似性证据。发现奥兰戈冠螺的I样基因家族与靶向钾通道的I(2)芋螺毒素超家族有关。大多数假定的奥兰戈冠螺毒素是富含半胱氨酸的多肽，其中很大一部分（超过80个氨基酸）比芋螺毒素大得多。少数不是富含半胱氨酸的，但有疏水氨基酸簇穿插着精氨酸残基。这只是10000多种不同塔螺毒液中需要表征的一种。这项研究表明，一类假定的塔螺毒素与芋螺有共同的起源。
