Evguenieva-Hackenberg Elena, Klug Gabriele
University of Giessen, Giessen, Germany.
Prog Mol Biol Transl Sci. 2009;85:275-317. doi: 10.1016/S0079-6603(08)00807-6.
Exoribonucleolytic and endoribonucleolytic activities are important for controlled degradation of RNA and contribute to the regulation of gene expression at the posttranscriptional level by influencing the half-lives of specific messenger RNAs. The RNA half-lives are determined by the characteristics of the RNA substrates and by the availability and the properties of the involved proteins-ribonucleases and assisting polypeptides. Much is known about RNA degradation in Eukarya and Bacteria, but there is limited information about RNA-degrading enzymes and RNA destabilizing or stabilizing elements in the domain of the Archaea. The recent progress in the understanding of the structure and function of the archaeal exosome, a protein complex with RNA-degrading and RNA-tailing capabilities, has given some first insights into the mechanisms of RNA degradation in the third domain of life and into the evolution of RNA-degrading enzymes. Moreover, other archaeal RNases with degrading potential have been described and a new mechanism for protection of the 5'-end of RNA in Archaea was discovered. Here, we summarize the current knowledge on RNA degradation in the Archaea. Additionally, RNA degradation mechanisms in Rhodobacter capsulatus and Pseudomonas syringae are compared to those in the major model organism for Gram-negatives, Escherichia coli, which dominates our view on RNA degradation in Bacteria.
外切核糖核酸酶活性和内切核糖核酸酶活性对于RNA的可控降解至关重要，并通过影响特定信使RNA的半衰期在转录后水平上参与基因表达的调控。RNA半衰期由RNA底物的特性以及相关蛋白质（核糖核酸酶和辅助多肽）的可用性和性质决定。关于真核生物和细菌中的RNA降解已有很多了解，但关于古菌域中RNA降解酶以及RNA不稳定或稳定元件的信息有限。最近在理解古菌外切体（一种具有RNA降解和RNA加尾能力的蛋白质复合物）的结构和功能方面取得的进展，为生命的第三个域中的RNA降解机制以及RNA降解酶的进化提供了一些初步见解。此外，还描述了其他具有降解潜力的古菌核糖核酸酶，并发现了古菌中保护RNA 5'端的新机制。在这里，我们总结了目前关于古菌中RNA降解的知识。此外，将荚膜红细菌和丁香假单胞菌中的RNA降解机制与革兰氏阴性菌的主要模式生物大肠杆菌中的机制进行了比较，大肠杆菌主导了我们对细菌中RNA降解的看法。
