鲤鱼线粒体URFA6L基因和tRNA~(Lys)基因的结构分析

鲤鱼线粒体URFA6L基因全长165个核苷酸,其结构同爪蟾URFA6L基因非常相似,它们的核苷酸序列间有68％的同源性.鲤鱼URFA6L蛋白共有54个氨基酸,它的组成成分极不寻常,几乎半数是属于5种疏水氨基酸(脯氨酸、色氨酸、亮氨酸、异亮氨酸、酪氨酸).比较了5种脊椎动物URFA6L蛋白和酵母ATP酶亚基8的氨基酸序列,发现它们有一些相同的结构特点,推测脊椎动物URFA6L蛋白起着ATP酶亚基8的作用.我们还测定了鲤鱼线粒体赖氨酸tRNA基因的核苷酸序列,并绘制了三叶草形的二级结构.鲤鱼线粒体rRNA~(Lys)基因同两栖类和哺乳类的tRNA~(Lys)基因一样,有许多不同于细胞质tRNA~(Lys)基因的不寻常结构特点.比较了7种脊椎动物tRNA~(Lys)基因的核苷酸序列,发现最保守的部分是反密码环、第8和第9个核苷酸、可变区、反密码茎和氨基酸接受臂.最不保守的区域是D-环和T-环.这些结构特点可能反映了线粒体tRNA~(Lys)同线粒体核糖体有不寻常的作用方式.     

STRUCTURE OF THE MITOCHONDRIAL URFA6L GENE AND tRNA~(Lys) GENE FROM CARP

The carp mitochondrial URFA6L gene consists of 165 base pairs. The overall structural organization of the gene is very similar to that of the Xenopus URFA6L gene. Their nucleotide sequences exhibit 68% homology. The carp URFA6L gene encodes a protein of 54 amino acids. The amino acid composition of the protein is unusual because almost half of the residues consist of 5 hydrophobic amino acids(proline, tryptophan, leueine, isoleueine and tyrosine). A comparison between the amino acid sequences of 5 vertebrate URFA6L proteins and the yeast ATPase8 showed that they have weak but very important common structural features, suggesting that the vertebrate URFA6L proteins may function asATPase8. The nucleotide sequence of the lysine tRNA gene from carp has been determined and represented in cloverleaf secondary structure. Similar to amphibian and mammalian mitochondrial tRNA~(Lys) genes, the carp mitochondrial tRNA~(Tys) gene also has some unusual structural features as compared with its cytoplasmic counterpart