Militello K T, Read L K
Department of Microbiology and Center for Microbial Pathogenesis, SUNY at Buffalo School of Medicine, Buffalo, NY 14214, USA.
Nucleic Acids Res. 1999 Mar 1;27(5):1377-85. doi: 10.1093/nar/27.5.1377.
Mitochondrial RNAs in Trypanosoma brucei are post-transcriptionally modified by the addition and deletion of uridylate residues in a process called kRNA editing. Unedited, partially edited and fully edited RNAs exist in the steady-state RNA population. Previous experiments have demonstrated that T.brucei mitochondrial RNAs contain both short (approximately 20 nt) and long (120-200 nt) poly(A) tracts. However, it is unknown exactly what poly(A) tract lengths are present on unedited, partially edited and fully edited RNAs. To gain insight into the role of the poly(A) tract in T.brucei mitochondria, ribosomal protein S12 (RPS12) RNAs with short and long poly(A) tracts were purified by hybrid selection and analyzed by RT-PCR and DNA sequencing. Unedited RPS12 RNAs were found almost exclusively in populations with short poly(A) tracts. Both partially and fully edited RPS12 RNAs were found in populations with short and long poly(A) tracts. Therefore, there is a correlation between the presence of editing and the presence of the long poly(A) tract. Since a proportion of partially edited RPS12 RNAs contain long poly(A) tracts, it is unlikely that the long poly(A) tract is the sole signal for translation. Other implications for the role of polyadenylation in mitochondrial gene regulation are discussed.
布氏锥虫中的线粒体RNA在转录后通过尿苷酸残基的添加和缺失进行修饰，这一过程称为kRNA编辑。未编辑、部分编辑和完全编辑的RNA存在于稳态RNA群体中。先前的实验表明，布氏锥虫线粒体RNA同时含有短（约20个核苷酸）和长（120 - 200个核苷酸）的聚腺苷酸尾。然而，目前尚不清楚未编辑、部分编辑和完全编辑的RNA上具体存在哪些聚腺苷酸尾长度。为了深入了解聚腺苷酸尾在布氏锥虫线粒体中的作用，通过杂交筛选纯化了具有短和长聚腺苷酸尾的核糖体蛋白S12（RPS12）RNA，并通过逆转录聚合酶链反应（RT-PCR）和DNA测序进行分析。未编辑的RPS12 RNA几乎只存在于具有短聚腺苷酸尾的群体中。部分编辑和完全编辑的RPS12 RNA在具有短和长聚腺苷酸尾的群体中均有发现。因此，编辑的存在与长聚腺苷酸尾的存在之间存在相关性。由于一部分部分编辑的RPS12 RNA含有长聚腺苷酸尾，长聚腺苷酸尾不太可能是翻译的唯一信号。文中还讨论了聚腺苷酸化在线粒体基因调控中的其他作用。
