Zhu Shunyi, Darbon Herve, Dyason Karin, Verdonck Fons, Tytgat Jan
Laboratory of Toxicology, University of Leuven, Belgium.
FASEB J. 2003 Sep;17(12):1765-7. doi: 10.1096/fj.02-1044fje. Epub 2003 Jul 3.
The inhibitor cystine knot (ICK) fold is an evolutionarily conserved structural motif shared by a large group of polypeptides with diverse sequences and bioactivities. Although found in different phyla (animal, plant, and fungus), ICK peptides appear to be most prominent in venoms of cone snail and spider. Recently, two scorpion toxins activating a calcium release channel have been found to adopt an ICK fold. We have isolated and identified both cDNA and genomic clones for this family of ICK peptides from the scorpion Opistophthalmus carinatus. The gene characterized by three well-delineated exons respectively coding for three structural and functional domains in the toxin precursors illustrates the correlation between exon and module as suggested by the "exon theory of genes." Based on the analysis of precursor organization and gene structure combined with the 3-D fold and functional data, our results highlight a common evolutionary origin for ICK peptides from animals. In contrast, ICK peptides from plant and fungus might be independently evolved from another ancestor.
抑制性胱氨酸结（ICK）折叠是一大类具有不同序列和生物活性的多肽所共有的一种进化上保守的结构基序。尽管在不同的门（动物、植物和真菌）中都有发现，但ICK肽似乎在芋螺和蜘蛛的毒液中最为突出。最近，发现两种激活钙释放通道的蝎毒素采用了ICK折叠。我们已经从蝎Opistophthalmus carinatus中分离并鉴定了该ICK肽家族的cDNA和基因组克隆。该基因由三个明确的外显子组成，分别编码毒素前体中的三个结构和功能结构域，这说明了“基因外显子理论”所提出的外显子与模块之间的相关性。基于对前体组织和基因结构的分析，并结合三维折叠和功能数据，我们的结果突出了动物ICK肽的共同进化起源。相比之下，植物和真菌中的ICK肽可能是从另一个祖先独立进化而来的。
