Mathy Nathalie, Bénard Lionel, Pellegrini Olivier, Daou Roula, Wen Tingyi, Condon Ciarán
CNRS UPR 9073 (affiliated with Université de Paris 7 - Denis Diderot), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris.
Cell. 2007 May 18;129(4):681-92. doi: 10.1016/j.cell.2007.02.051.
Although the primary mechanism of eukaryotic messenger RNA decay is exoribonucleolytic degradation in the 5'-to-3' orientation, it has been widely accepted that Bacteria can only degrade RNAs with the opposite polarity, i.e. 3' to 5'. Here we show that maturation of the 5' side of Bacillus subtilis 16S ribosomal RNA occurs via a 5'-to-3' exonucleolytic pathway, catalyzed by the widely distributed essential ribonuclease RNase J1. The presence of a 5'-to-3' exoribonuclease activity in B. subtilis suggested an explanation for the phenomenon whereby mRNAs in this organism are stabilized for great distances downstream of "roadblocks" such as stalled ribosomes or stable secondary structures, whereas upstream sequences are never detected. We show that a 30S ribosomal subunit bound to a Shine Dalgarno-like element (Stab-SD) in the cryIIIA mRNA blocks exonucleolytic progression of RNase J1, accounting for the stabilizing effect of this element in vivo.
虽然真核生物信使核糖核酸（mRNA）降解的主要机制是5′至3′方向的外切核糖核酸酶降解，但人们普遍认为细菌只能降解相反极性的RNA，即3′至5′。在此我们表明，枯草芽孢杆菌16S核糖体RNA 5′端的成熟是通过一种5′至3′的外切核酸酶途径发生的，该途径由广泛分布的必需核糖核酸酶RNase J1催化。枯草芽孢杆菌中存在5′至3′的外切核糖核酸酶活性，这为该生物体中的mRNA在诸如停滞核糖体或稳定二级结构等“路障”下游很长距离内稳定，而上游序列从未被检测到这一现象提供了解释。我们表明，与cryIIIA mRNA中类似Shine Dalgarno元件（Stab-SD）结合的30S核糖体亚基会阻断RNase J1的外切核酸酶作用进程，这解释了该元件在体内的稳定作用。
