Feagin J E, Werner E, Gardner M J, Williamson D H, Wilson R J
Seattle Biomedical Research Institute, WA 98109-1651.
Nucleic Acids Res. 1992 Feb 25;20(4):879-87. doi: 10.1093/nar/20.4.879.
Plasmodium falciparum contains two extrachromosomal DNAs, a 6 kb linear element and a 35 kb circular DNA; both encode rDNA sequences. The 6 kb element rDNAs comprise fragments of both large and small subunit rRNAs. Comparison of these with corresponding rDNA sequences from the 35 kb DNA and E. coli show that sequences conserved between the three are largely confined to highly conserved core regions; in fact, most of the 6 kb rDNA sequences correspond to core regions. Both the 6 kb element and 35 kb rDNAs show less conservation to each other than to E. coli sequences, suggesting that the two extrachromosomal DNAs of P. falciparum are not closely related. The characteristics of the fragmented rRNAs from the 6 kb element suggest they are functional, possibly in mitochondrial ribosomes.
恶性疟原虫含有两种染色体外DNA，一种是6 kb的线性元件，另一种是35 kb的环状DNA；两者都编码核糖体DNA（rDNA）序列。6 kb元件的rDNA由大亚基和小亚基rRNA的片段组成。将这些片段与来自35 kb DNA和大肠杆菌的相应rDNA序列进行比较，结果表明三者之间保守的序列主要局限于高度保守的核心区域；事实上，6 kb rDNA序列的大部分对应于核心区域。与大肠杆菌序列相比，6 kb元件和35 kb rDNA彼此之间的保守性更低，这表明恶性疟原虫的两种染色体外DNA没有密切关系。来自6 kb元件的片段化rRNA的特征表明它们具有功能，可能在线粒体核糖体中发挥作用。
