Ribonuclease E is a 5′-end-dependent endonuclease
Ribonuclease E is a 5′-end-dependent endonuclease
复制标题
DOI：
10.1038/27246
复制
发表时间：
1998-10-15
期刊：
影响因子：
64.8
通讯作者：
Mackie, GA
中科院分区：
文献类型：
--
作者：
Mackie, GA
信使RNA的选择性降解使细胞能够调节特定mRNAs的水平，以应对环境的变化。核糖核酸酶(RNase)E(ref，1)是一种单链特异性内切酶(2-4)，存在于被称为降解体(5-7)的多酶复合体中，启动了许多在大肠杆菌(3，8，9)中的mRNAs的降解。其相对缺乏序列特异性和在信使核糖核酸底物(2，3)中存在许多潜在的切割父系，不能解释为什么信使核糖核酸经常以5‘到3’方向进行(9-11)。我已经制备了天然底物的共价剂量环状衍生物，编码核糖体蛋白S20的rpsT mRNA(参考文献)。2)和5S核糖体RNA的9S前体(1，12)，发现这些衍生物比线性分子更能抵抗RNase E的体外切割。此外，与线性底物5‘端互补的反义寡核苷酸显著降低了后者被RNase E攻击的敏感性。最后，RNase E体外切割末端为5’-h三磷酸基团的天然底物很难被RNase E切割，而5‘端单磷酸化底物则强烈被RNase E切割(与参考文献13相比)。这些结果表明，RNaseE具有固有的：载体性质，其活性取决于其底物的5‘端；这可以解释E，Coli中mRNA衰退的方向，’全有‘或’全无‘的mRNA衰退现象，以及5’茎环结构(14-17)提供的稳定性。
The selective degradation of messenger RNAs enables cells to regulate the levels of particular mRNAs in response to changes in the environment. Ribonuclease (RNase) E (ref, 1), a single-strand-specific endonuclease(2-4) that is found in a multi-enzyme complex known as the 'degradosome'(5-7), initiates the degradation of many mRNAs in Escherichia coli(3,8,9). Its relative lack of sequence specificity and the presence of many potential cleavage sires in mRNA substrate(2,3) cannot explain why mRNA decay frequently proceeds in a net 5'-to-3' directian(9-11). I have prepared covalently dosed circular derivatives of natural substrates, the rpsT mRNA encoding ribosomal protein S20 (ref. 2) and the 9S precursor to 5S ribosomal RNA(1,12), and find that these derivatives are considerably more resistant to cleavage in vitro by RNase E than are linear molecules. Moreover, antisense oligo-deoxynucleotides complementary to the 5' end of linear substrates significantly reduce the latter's susceptibility to attack by RNase E. Finally, natural substrates with terminal 5'-h triphosphate groups are poorly cleaved by RNase E in vitro, whereas 5' monophosphorylated substrates are strongly preferred (compare with ref, 13). These results show that RNase E has inherent: vectorial properties, with its activity depending on the 5' end of its substrates; this can account for the direction of mRNA decay in E, coli, the phenomenon of 'all or none' mRNA decay, and the stabilization provided by 5' stem-loop structures(14-17).