The enigmatic RNase MRP of kinetoplastids

The ribonucleoprotein RNase MRP is responsible for the processing of ribosomal RNA precursors. It is found in virtually all eukaryotes that have been examined. In the Euglenozoa, including the genera Euglena, Diplonema and kinetoplastids, MRP RNA and protein subunits have so far escaped detection using bioinformatic methods. However, we now demonstrate that the RNA component is widespread among the Euglenozoa and that these RNAs have secondary structures that conform to the structure of all other phylogenetic groups. In Euglena, we identified the same set of P/MRP protein subunits as in many other protists. However, we failed to identify any of these proteins in the kinetoplastids. This finding poses interesting questions regarding the structure and function of RNase MRP in these species.

核糖核酸酶MRP（RNase MRP）是一类核糖核蛋白复合物，负责催化核糖体RNA前体的加工过程。目前已完成检测的真核生物中，几乎均存在该酶复合物。在眼虫门（Euglenozoa）类群（涵盖眼虫属（Euglena）、双滴虫属（Diplonema）及动质体目（kinetoplastids）物种）中，此前通过生物信息学方法始终未能检测到MRP RNA及其蛋白质亚基。但本研究证实，MRP RNA在眼虫门类群中广泛分布，且此类RNA的二级结构与其他所有系统发育类群的对应结构完全一致。在眼虫属中，本研究鉴定出与多数其他原生生物相同的P/MRP蛋白质亚基组合；但在动质体目物种中，未能检测到任何此类蛋白质亚基。这一发现为探究此类物种中核糖核酸酶MRP的结构与功能提出了值得深入探讨的科学问题。