Institute of Biochemistry and Biophysics, Polish Academy of Sciences, University of Warsaw, 02-106 Warsaw, Poland.
RNA. 2010 Sep;16(9):1692-724. doi: 10.1261/rna.2237610. Epub 2010 Jul 30.
For a long time it has been assumed that the decay of RNA in eukaryotes is mainly carried out by exoribonucleases, which is in contrast to bacteria, where endoribonucleases are well documented to initiate RNA degradation. In recent years, several as yet unknown endonucleases have been described, which has changed our view on eukaryotic RNA metabolism. Most importantly, it was shown that the primary eukaryotic 3' --> 5' exonuclease, the exosome complex has the ability to endonucleolytically cleave its physiological RNA substrates, and novel endonucleases involved in both nuclear and cytoplasmic RNA surveillance pathways were discovered concurrently. In addition, endoribonucleases responsible for long-known processing steps in the maturation pathways of various RNA classes were recently identified. Moreover, one of the most intensely studied RNA decay pathways--RNAi--is controlled and stimulated by the action of different endonucleases. Furthermore, endoribonucleolytic cleavages executed by various enzymes are also the hallmark of RNA degradation and processing in plant chloroplasts. Finally, multiple context-specific endoribonucleases control qualitative and/or quantitative changes of selected transcripts under particular conditions in different eukaryotic organisms. The aim of this review is to discuss the impact of all of these discoveries on our current understanding of eukaryotic RNA metabolism.
长期以来，人们一直认为真核生物中的 RNA 衰变主要是由核糖核酸外切酶进行的，而在细菌中，内切核糖核酸酶已被很好地证明可以启动 RNA 降解。近年来，已经描述了几种尚未被发现的内切核酸酶，这改变了我们对真核生物 RNA 代谢的看法。最重要的是，研究表明，主要的真核生物 3' --> 5' 外切核酸酶——核酶复合物具有内切核酸酶切割其生理 RNA 底物的能力，并且同时发现了参与核和细胞质 RNA 监测途径的新型内切核酸酶。此外，最近还鉴定出负责各种 RNA 类成熟途径中已知加工步骤的内切核糖核酸酶。此外，研究最深入的 RNA 衰变途径之一——RNAi——受到不同内切核酸酶的控制和刺激。此外，各种酶执行的内切核酸裂解也是植物叶绿体中 RNA 降解和加工的标志。最后，在不同的真核生物中，多种特定于上下文的内切核酸酶在特定条件下控制特定转录本的定性和/或定量变化。本文的目的是讨论所有这些发现对我们目前对真核生物 RNA 代谢理解的影响。
