Okamoto K, Sekito T, Yoshida K
Department of Biological Science, Faculty of Science, Hiroshima University, Japan.
Genes Genet Syst. 1996 Apr;71(2):69-74. doi: 10.1266/ggs.71.69.
We have accomplished the nucleotide sequence of the 1537 bp mitochondrial gene coding for small subunit (SSU) rRNA of yeast Hansenula wingei, and also determined the 5'- and 3'-termini by S1 nuclease mapping. Eight universally conserved (U) elements of the SSU rRNA were identified. Comparison of U regions among five fungal mitochondrial SSU rRNA shows the striking similarity between H. wingei and Saccharomyces cerevisiae. The construction of the secondary structure revealed a core structure similar to the counterpart of Escherichia coli 16S rRNA. The secondary structure also enabled us the specify seven variable (V) regions differing from those of other mitochondrial SSU rRNAs in size, sequence and possible secondary structure. Molecular phylogenetic evaluation based on U regions of five fungi indicates that mitochondria of H. wingei and S. cerevisiae diverged from the same lineage. This suggests that the evolution of mitochondria-encoded genes does not directly correlate with the alteration of mitochondrial genetic system: genome size, gene organization and codon usage.
我们已经完成了汉逊酵母（Hansenula wingei）编码小亚基（SSU）rRNA的1537bp线粒体基因的核苷酸序列测定，并通过S1核酸酶图谱分析确定了其5'和3'末端。鉴定出了SSU rRNA的八个普遍保守（U）元件。对五种真菌线粒体SSU rRNA的U区域进行比较，发现汉逊酵母和酿酒酵母（Saccharomyces cerevisiae）之间存在显著相似性。二级结构的构建揭示了一个与大肠杆菌16S rRNA对应物相似的核心结构。二级结构还使我们能够确定七个可变（V）区域，这些区域在大小、序列和可能的二级结构方面与其他线粒体SSU rRNAs不同。基于五种真菌U区域的分子系统发育评估表明，汉逊酵母和酿酒酵母的线粒体起源于同一谱系。这表明线粒体编码基因的进化与线粒体遗传系统的改变（基因组大小、基因组织和密码子使用）没有直接关联。
