Cantatore P, Roberti M, Rainaldi G, Gadaleta M N, Saccone C
Department of Biochemistry and Molecular Biology, University of Bari, Italy.
J Biol Chem. 1989 Jul 5;264(19):10965-75.
The 15,697-nucleotide sequence of Paracentrotus lividus mitochondrial DNA is reported. This genome codes for 2 rRNAs, 22 tRNAs, and 12 mRNAs which specify 13 subunits of the mitochondrial inner membrane respiratory complexes. The gene arrangement differs from that of other animal species. The two ribosomal genes 16 S and 12 S are separated by a stretch of about 3.3 kilobase pairs which contains the ND1 and ND2 genes and a cluster of 15 tRNA genes. The ND4L coding sequence is not contained in the ND4 mRNA but has its own mRNA which maps between the tRNA(Arg) and the Co II genes. The main noncoding region, located in the tRNA gene cluster, is only 132 nucleotides long, but contains sequences homologous to the mammalian displacement loop. Other short noncoding sequences are interspersed in the genome: they contain a conserved AT consensus which probably has a role in transcription or RNA processing. As regards the mitochondrial genetic code, the codons AGA and AGG specify serine and are recognized by a tRNA with a GCU anticodon, whereas AUA and AAA code for isoleucine and asparagine rather than for methionine and lysine. Except for ND4L which starts with AUC and ATPase 8 which starts with GUG, AUG is used as the initiation codon. In 11 out of 13 cases the genes terminate with the canonical stop codons UAA or UAG. These observations suggest that during invertebrate evolution each lineage developed its own mechanism of mitochondrial DNA replication and transcription and of RNA processing and translation.
报道了紫海胆线粒体DNA的15,697个核苷酸序列。该基因组编码2个rRNA、22个tRNA和12个mRNA，这些mRNA指定了线粒体内膜呼吸复合物的13个亚基。基因排列与其他动物物种不同。两个核糖体基因16S和12S被一段约3.3千碱基对的序列隔开，该序列包含ND1和ND2基因以及15个tRNA基因簇。ND4L编码序列不包含在ND4 mRNA中，而是有自己的mRNA，定位于tRNA(Arg)和Co II基因之间。主要的非编码区位于tRNA基因簇中，仅132个核苷酸长，但包含与哺乳动物替代环同源的序列。其他短的非编码序列散布在基因组中：它们包含一个保守的AT共有序列，可能在转录或RNA加工中起作用。关于线粒体遗传密码，密码子AGA和AGG指定丝氨酸，并被具有GCU反密码子的tRNA识别，而AUA和AAA编码异亮氨酸和天冬酰胺，而不是甲硫氨酸和赖氨酸。除了以AUC起始的ND4L和以GUG起始的ATPase 8外，AUG用作起始密码子。在13个例子中的11个中，基因以典型的终止密码子UAA或UAG终止。这些观察结果表明，在无脊椎动物进化过程中，每个谱系都发展出了自己的线粒体DNA复制、转录以及RNA加工和翻译机制。
