Luo Sulan, Zhangsun Dongting, Feng Jiancheng, Wu Yong, Zhu Xiaopeng, Hu Yuanyan
Key Laboratory for Tropical Biological Resources, (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University; Haikou Hainan, 570228 China.
J Pept Sci. 2007 Jan;13(1):44-53. doi: 10.1002/psc.802.
Conopeptides display prominent features of hypervariability and high selectivity of large gene families that mediate interactions between organisms. Remarkable sequence diversity of O-superfamily conotoxins was found in a worm-hunting cone snail Conus miles. Five novel cDNA sequences encoding O-superfamily precursor peptides were identified in C. miles native to Hainan by RT-PCR and 3'-RACE. They share the common cysteine pattern of the O-superfamily conotoxin (C-C-CC-C-C, with three disulfide bridges). The predicted peptides consist of 27-33 amino acids. We then performed a phylogenetic analysis of the new and published homologue sequences from C. miles and the other Conus species. Sequence divergence (%) and residue substitutions to view evolutionary relationships of the precursors' signal, propeptide, and mature toxin regions were analyzed. Percentage divergence of the amino acid sequences of the prepro region exhibited high conservation, whereas the sequences of the mature peptides ranged from almost identical with to highly divergent from inter- and intra-species. Despite the O-superfamily being a large and diverse group of peptides, widely distributed in the venom ducts of all major feeding types of Conus and discovered in several Conus species, it was for the first time that the newly found five O-superfamily peptides in this research came from the vermivorous C. miles. So far, conotoxins of the O-superfamily whose properties have been characterized are from piscivorous and molluscivorous Conus species, and their amino acid sequences and mode of action have been discussed in detail. The elucidated cDNAs of the five toxins are new and of importance and should attract the interest of researchers in the field, which would pave the way for a better understanding of the relationship of their structure and function.
芋螺肽显示出大型基因家族的高度变异性和高选择性的显著特征，这些基因家族介导生物体之间的相互作用。在以蠕虫为食的芋螺Conus miles中发现了O-超家族芋螺毒素显著的序列多样性。通过RT-PCR和3'-RACE在海南原产的C. miles中鉴定出五个编码O-超家族前体肽的新cDNA序列。它们共享O-超家族芋螺毒素的常见半胱氨酸模式（C-C-CC-C-C，具有三个二硫键）。预测的肽由27-33个氨基酸组成。然后，我们对来自C. miles和其他芋螺物种的新的和已发表的同源序列进行了系统发育分析。分析了序列分歧（%）和残基取代，以观察前体的信号、前肽和成熟毒素区域的进化关系。前原区域氨基酸序列的分歧百分比表现出高度保守性，而成熟肽的序列在种间和种内从几乎相同到高度不同。尽管O-超家族是一大类多样的肽，广泛分布于所有主要摄食类型的芋螺的毒管中，并在几种芋螺物种中被发现，但本研究中新发现的五个O-超家族肽首次来自食虫的C. miles。到目前为止，其特性已被表征的O-超家族芋螺毒素来自食鱼和食软体动物的芋螺物种，并且它们的氨基酸序列和作用方式已经被详细讨论。阐明的这五种毒素的cDNA是新的且具有重要意义，应该会引起该领域研究人员的兴趣，这将为更好地理解它们的结构与功能的关系铺平道路。
