Department of Biomolecular Sciences and Biotechnology, University of Milano, Via Celoria 26, 20133 Milano, Italy.
Mol Microbiol. 2011 Dec;82(5):1260-76. doi: 10.1111/j.1365-2958.2011.07888.x. Epub 2011 Nov 3.
The presence of very different sets of enzymes, and in particular the presence of RNase E and RNase J, has been used to explain significant differences in RNA metabolism between the two model organisms Escherichia coli and Bacillus subtilis. However, these studies might have somewhat polarized our view of RNA metabolism. Here, we identified a RNase J in Mycobacterium smegmatis that has both 5'-3' exo- and endonucleolytic activity. This enzyme coexists with RNase E in this organism, a configuration that enabled us to study how these two key nucleases collaborate. We demonstrate that RNase E is responsible for the processing of the furA-katG transcript in M. smegmatis and that both RNase E and RNase J are involved in the 5' end processing of all ribosomal RNAs. In contrast to B. subtilis, the activity of RNase J, although required in vivo for 23S rRNA maturation, is not essential in M. smegmatis. We show that the pathways for ribosomal RNA maturation in M. smegmatis are quite different from those observed in E. coli and in B. subtilis. Studying organisms containing different combinations of key ribonucleases can thus significantly broaden our view of the possible strategies that exist to direct RNA metabolism.
存在非常不同的酶组，特别是存在 RNase E 和 RNase J，这被用来解释两种模式生物大肠杆菌和枯草芽孢杆菌之间的 RNA 代谢的显著差异。然而，这些研究可能在一定程度上使我们对 RNA 代谢的看法有些片面。在这里，我们在耻垢分枝杆菌中鉴定出一种具有 5'-3' 外切和内切核酸酶活性的 RNase J。这种酶与该生物体内的 RNase E 共存，这种结构使我们能够研究这两种关键核酸酶如何协作。我们证明，RNase E 负责处理耻垢分枝杆菌中的 furA-katG 转录物，并且 RNase E 和 RNase J 都参与所有核糖体 RNA 的 5' 端加工。与枯草芽孢杆菌不同，RNase J 的活性虽然在体内对 23S rRNA 成熟是必需的，但在耻垢分枝杆菌中并非必不可少。我们表明，耻垢分枝杆菌中核糖体 RNA 成熟的途径与在大肠杆菌和枯草芽孢杆菌中观察到的途径有很大的不同。因此，研究含有不同关键核糖核酸酶组合的生物体可以极大地拓宽我们对存在的指导 RNA 代谢的可能策略的认识。
