三角帆蚌金属硫蛋白基因的克隆及序列分析

Cloning and Sequence Analysis of Metallothionein Gene in Hyriopsis cumingii

采用RACE技术,获得了三角帆蚌(Hyriopsis cumingii)金属硫蛋白基因的全长cDNA序列。该序列全长467 bp,由长92 bp的5′UTR(untranslated region),159 bp的3′UTR,和216 bp的开放阅读框(openreadingframe,ORF)组成。共编码71个氨基酸,分子量大约为7.1 ku,理论等电点为7.24。该蛋白序列中半胱氨酸含量最丰富(29.6%),其次是甘氨酸(14.1%),存在软体动物金属硫蛋白的特征序列CKCXXXCXCX,且C-末端的氨基酸序列也符合软体动物金属硫蛋白标签序列C-X-C-X(3)-C-T-G-X(3)-C-X-C-X(3)-C-X-C-K。蛋白序列特征分析表明,该序列与其他贝类的金属硫蛋白基因具有很高的相似性,具备金属硫蛋白的典型特征,是金属硫蛋白家族的成员。

A 467 bp full-length cDNA sequence of metallothionein （named as HCMT） gene was obtained using rapid amplification of cDNA end （RACE） technique in Hyriopsis cumingii. It consists of a 92 bp 5＇ untranslated region （UTR）, a 216 bp open reading frame （ORF） and a 159 bp 3＇UTR. The translated protein was composed of 71 amino acids, with a molecular weight of 7.1 ku, and its calculated isoelectric point was 7.24. The contents of eysteine and glycine in the predicted HCMT amino acid sequence were 29.6% and 14.1% , respectively. The conserved motif CKCXXXCXCX of molluscan MT was also found in HCMT. A specific pattern of molluscan MT C-X-C-X（3）-C-T-G- X（3）-C-X-C-X（3）-C-X-C-K was located at the C-terminal. The predicted protein sequence analysis showed that the MT of H. cumingii had the typical characteristics of MT family and shared a high similarity with that of other molluscans.