Plagens André, Daume Michael, Wiegel Julia, Randau Lennart
Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
LOEWE Center for Synthetic Microbiology, Synmikro, Marburg, Germany.
Elife. 2015 Oct 24;4:e11623. doi: 10.7554/eLife.11623.
Signal recognition particles (SRPs) are universal ribonucleoprotein complexes found in all three domains of life that direct the cellular traffic and secretion of proteins. These complexes consist of SRP proteins and a single, highly structured SRP RNA. Canonical SRP RNA genes have not been identified for some Thermoproteus species even though they contain SRP19 and SRP54 proteins. Here, we show that genome rearrangement events in Thermoproteus tenax created a permuted SRP RNA gene. The 5'- and 3'-termini of this SRP RNA are located close to a functionally important loop present in all known SRP RNAs. RNA-Seq analyses revealed that these termini are ligated together to generate circular SRP RNA molecules that can bind to SRP19 and SRP54. The circularization site is processed by the tRNA splicing endonuclease. This moonlighting activity of the tRNA splicing machinery permits the permutation of the SRP RNA and creates highly stable and functional circular RNA molecules.
信号识别颗粒（SRP）是在生命的所有三个域中都存在的通用核糖核蛋白复合物，负责指导蛋白质的细胞运输和分泌。这些复合物由SRP蛋白和单个高度结构化的SRP RNA组成。尽管某些嗜热栖热菌物种含有SRP19和SRP54蛋白，但尚未鉴定出其典型的SRP RNA基因。在这里，我们表明嗜热栖热菌中的基因组重排事件产生了一个重排的SRP RNA基因。该SRP RNA的5'和3'末端靠近所有已知SRP RNA中存在的一个功能重要的环。RNA测序分析表明，这些末端连接在一起以产生可与SRP19和SRP54结合的环状SRP RNA分子。环化位点由tRNA剪接内切核酸酶处理。tRNA剪接机制的这种兼职活性允许SRP RNA重排，并产生高度稳定且功能正常的环状RNA分子。
