一个新的东亚钳蝎毒素(BmKT_1)全长cDNA的克隆和分析

首先构建了东亚钳蝎毒腺组织 c DNA文库 ;根据已知的东亚钳蝎哺乳动物毒素氨基酸序列保守区设计引物 ,并用 PCR从 c DNA文库中扩增出一个 c DNA片段作为筛选 c DNA文库的探针 ;从 c DNA文库中筛选到二个编码同一个新的蝎毒素多肽的 c DNA,它们除 3′- UTR外 ,其余序列完全一致 .它们均含有 2 55bp长的开放阅读框 ,编码 85肽的前体毒素 ,包括 1 9个氨基酸残基的信号肽 ,66个残基的成熟毒素 (命名为 Bm KT1) ;Bm KT1氨基酸序列与已知的蝎毒素具有较大的同源性 ,与 Bm KM1,Lqq ,Lqhα IT和 Bm K M10 的同源性分别为 77%、67%、67%和 65% .Bm KT1的 C端不存在末端修饰步骤且具有一个与这些毒素不相同的特征结构 ,即在末端延伸了两个氨基酸残基 - P- S,推测 Bm KT1具有新的活性功能特征 .

Cloning and Characterization of the Full Length cDNA Sequence of a New Venom Peptide(BmKT_1)from Chinese Scorpion Buthus martensii Karsch

A cDNA library was constructed from the venom gland of Chinese scorpion Buthus martensii Karsch(BmK).A cDNA probe for screening the cDNA library was obtained by PCR amplification with primers designed and synthesized according to the conserved sequences of BmK mammalian neurotoxins.With the probe,two cDNAs of a scorpion toxin were isolated from the library.Except for their 3′ UTR,other sequences of the two cDNAs were identical.Both the cDNAs displayed an ORF(open reading frame)of 255 bp,which encoded a toxin precursor of 85 residues including a signal peptide of 19 residues and a mature peptide(named BmKT 1)of 66 residues.The analysis of amino acid sequence similarity indicated that the BmKT 1 was homologous with some scorpion toxins,showing 77%,67%,67%,65% sequence identity with that of BmKM 1,LqqⅢ,Lqh α IT,BmKM 10 respectively.The C terminus of BmKT 1 has no modification and has a peculiar end structure compared with other toxins,showing two extended residues P S.The difference in 3′ UTR between the two cDNAs suggested that they were evolved from a common ancestor gene and an interesting evolution mechanism was underwent by the scorpion for adjusting to various environment.