Luo Sulan, Zhangsun Dongting, Zhang Ben, Chen Xin, Feng Jianchen
Key Laboratory for Tropical Biological Resources (MOE), Ocean College, Center for Experimental Biotechnology, Hainan University, Haikou Hainan 570228, China.
Peptides. 2006 Nov;27(11):2640-6. doi: 10.1016/j.peptides.2006.05.002. Epub 2006 Jun 12.
The T-superfamily is a large and diverse group of peptides, widely distributed in venom ducts of all major feeding types of Conus. These peptides are likely to be functionally diverse. A directed PCR-based approach using primers based on the conserved signal sequence was applied to investigate new conotoxins of the T-superfamily from Conus textile native to Hainan. Using RT-PCR and 3'-RACE, four novel cDNA sequences encoding precursor peptides were identified in C. textile. They share a common T-superfamily cysteine pattern (CC-CC, with two disulfide bridges). The predicted peptides are small (9-12 amino acids). TeAr193 composed of nine amino acid residues is one of the shortest T-superfamily conotoxins ever found. Patterns of sequence divergence and Cys codon usage define the major T-superfamily branches and suggest how these separate branches arose. The sequences of the signal regions exhibited highest conservation, whereas the sequences of the mature peptides were either almost identical or highly divergent; and conservation of the pro-region was intermediate between that observed in signal and toxin regions. The elucidated cDNAs of the four toxins will facilitate a better understanding of the relationship between structure and function.
T-超家族是一大类多样的肽，广泛分布于芋螺所有主要摄食类型的毒管中。这些肽可能具有多种功能。采用基于保守信号序列的引物进行定向PCR方法，研究来自海南的织锦芋螺T-超家族的新芋螺毒素。利用逆转录PCR（RT-PCR）和3'-末端快速扩增技术（3'-RACE），在织锦芋螺中鉴定出四个编码前体肽的新cDNA序列。它们具有共同的T-超家族半胱氨酸模式（CC-CC，有两个二硫键）。预测的肽段较小（9-12个氨基酸）。由九个氨基酸残基组成的TeAr193是迄今发现的最短的T-超家族芋螺毒素之一。序列分歧模式和半胱氨酸密码子使用情况定义了T-超家族的主要分支，并提示了这些不同分支的产生方式。信号区序列具有最高的保守性，而成熟肽段的序列要么几乎相同，要么高度分歧；前体区的保守性介于信号区和毒素区之间。阐明的四种毒素的cDNA将有助于更好地理解结构与功能之间的关系。
