Department of Biology, University of Utah, Salt Lake City, UT 84121, USA.
Curr Genet. 2013 Aug;59(3):139-52. doi: 10.1007/s00294-013-0395-9. Epub 2013 Jun 26.
The mitochondrial (mt) genome of the sea anemone Metridium senile contains genes for only two transfer RNAs (tRNAs), tRNAf-Met and tRNATrp. Experiments were conducted to seek evidence for the occurrence of functional tRNAs corresponding to these genes and for the participation of nuclear DNA-encoded tRNAs in mt-protein synthesis. RNA sequences corresponding to the two mt-tRNA genes were located in mitochondria and it was shown that 3'-CC (and possibly A, but no other nucleotide) is added post-transcriptionally to the 3' end of at least 50 % of mt-tRNAf-Met molecules and to a small fraction of the mt-tRNATrp molecules. Using specific oligonucleotide primers based on expected nuclear DNA-encoded tRNAs in a series of RACE experiments, we located the nuclear genes for tRNAGln, tRNAIle, tRNAi-Met, tRNAVal and tRNAThr. Data from Northern blot analyses indicated that mtDNA-encoded tRNAf-Met is limited to mitochondria but that nuclear DNA-encoded tRNAVal and tRNAi-Met are present in the cytoplasm and in mitochondria. These data provide direct evidence that in M. senile, mature, functional tRNAs are transcribed from the mtDNA-encoded tRNAf-Met and tRNATrp genes, and are consistent with the interpretation that both nuclear DNA-encoded tRNAVal and tRNAi-Met are utilized in mitochondrial and cytosolic protein synthesis.
海葵线粒体（mt）基因组仅包含两个转移 RNA（tRNA）的基因，tRNAf-Met 和 tRNATrp。进行了实验以寻找这些基因对应的功能 tRNA 出现的证据，以及核 DNA 编码的 tRNA 参与 mt 蛋白合成的证据。与这两个 mt-tRNA 基因相对应的 RNA 序列位于线粒体中，并且表明至少 50%的 mt-tRNAf-Met 分子和一小部分 mt-tRNATrp 分子的 3'端在转录后添加了 3'-CC（可能还有 A，但没有其他核苷酸）。通过一系列 RACE 实验中基于预期核 DNA 编码的 tRNA 的特异性寡核苷酸引物，我们定位了 tRNAGln、tRNAIle、tRNAi-Met、tRNAVal 和 tRNAThr 的核基因。来自 Northern blot 分析的数据表明，mtDNA 编码的 tRNAf-Met 仅限于线粒体，但核 DNA 编码的 tRNAVal 和 tRNAi-Met 存在于细胞质和线粒体中。这些数据提供了直接证据，表明在 M. senile 中，成熟的、功能性的 tRNA 是从 mtDNA 编码的 tRNAf-Met 和 tRNATrp 基因转录而来的，并且与核 DNA 编码的 tRNAVal 和 tRNAi-Met 都用于线粒体和细胞质蛋白合成的解释一致。
