Jourdan Stefanie S, McDowall Kenneth J
Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, England, UK.
Mol Microbiol. 2008 Jan;67(1):102-15. doi: 10.1111/j.1365-2958.2007.06028.x.
The RNase E/G family of endoribonucleases has a central role in RNA degradation and processing. Previous work has shown that their cleavage of substrates in vitro can be stimulated by the presence of a 5' monophosphate group. It has not however, established the importance of this activation for any natural RNA processing or decay pathway in vivo. Here we provide for Escherichia coli RNase G the first evidence that the sensing of a 5' monophosphate is required in vivo for the normal rapid decay of functional mRNAs; moreover, we show in vitro that, in contrast to a previous study, the presence of a 5' monophosphate can enhance the affinity of RNase G binding to RNA. The implications of these results along with our finding that the maturation of 16S rRNA is unaffected in cells containing an RNase G mutant impaired in 5' end sensing are discussed with regard to current models of RNA processing and decay and the molecular mechanism that underlies RNA cleavage by the RNase E/G family.
核糖核酸内切酶RNase E/G家族在RNA降解和加工过程中发挥着核心作用。此前的研究表明，体外存在5'单磷酸基团可刺激它们对底物的切割。然而，尚未确定这种激活对于体内任何天然RNA加工或降解途径的重要性。在此，我们首次为大肠杆菌RNase G提供证据，证明体内功能性mRNA的正常快速降解需要感知5'单磷酸；此外，我们在体外表明，与之前的一项研究相反，5'单磷酸的存在可增强RNase G与RNA结合的亲和力。结合当前的RNA加工和降解模型以及RNase E/G家族切割RNA的分子机制，讨论了这些结果的意义，以及我们发现5'末端感知受损的RNase G突变体的细胞中16S rRNA的成熟不受影响这一情况。
