草鱼(Ctenopharyngodon idellus)线粒体DNA控制区及其两侧tRNA基因的克隆与结构分析

Cloning and Structure Anaysis of the Mitochondrial Control Region and Its Flanking tRNA Genes From Grasscarp( Ctenopharyngodon idellus )

动物线粒体ＤＮＡ控制区是线粒体基因组复制与基因表达的最主要的调控区．采用杂交和测序的方法对草鱼线粒体ＤＮＡ控制区进行定位、克隆并测定了控制区及其旁侧的ｔＲＮＡＰｈｅ、ｒＲＮＡＰｒｏ和ｒＲＮＡＴｈｒ三个基因的序列，与多种脊椎动物的相应序列进行了比较，并进行了结构分析．草鱼线粒体控制区全长９２７ｂｐ，含有与酵母和爪蟾线粒体启动子相似的序列，其ＣＳＢⅠ、ＣＳＢⅡ和ＣＳＢⅢ序列与其他几种动物的ＣＳＢ比较相当保守，ＴＡＳ与其回文基序可形成稳定的茎环结构，成为Ｈ－链复制的终止信号．草鱼线粒体ｔＲＮＡＰｈｅ、ｔＲＮＡＰｒｏ和ｔＲＮＡＴｈｒ可折叠成三叶草形二级结构，其基因具有许多不同于细胞质ｔＲＮＡ基因的结构特点。

The mitochondrial control region is the most important noncoding region controlling replication and transcription of mitochondrial DNA.The nucleotide sequences of the control region and tRNA Phe ,tRNA Pro ,tRNA Thr genes from grasscarp( Ctenopharyngodon idellus )mitochondria had been cloned and determined,and then further compared with the homologous sequences of some kinds of vertebrates,and the secondary structures depicted.The grasscarp mitochondrial control region is 927 bp in length and its base composition is rich in A and T(67%).It includes putative promoters,CSBⅠ,Ⅱ,Ⅲ,and two TASes.The sequences and structures of putative promoters are similar to that of yeast and frog.CSBⅠ,Ⅱ,Ⅲ are conservative to the same regions of other kinds of vertebrates.TASes and their palidromic motifs can form stable hairpin loop structure acting as a recognition site for the termination of H strand elongation.The grasscarp mitochondrial tRNA Phe ,tRNA Pro ,tRNA Thr genes have cloverleaf secondary structures,and many structure features differing from those of cytoplasmic tRNA genes,which may reflect their unusual mode acting with mitochondrial ribosomes.