Britton Robert A, Wen Tingyi, Schaefer Laura, Pellegrini Olivier, Uicker William C, Mathy Nathalie, Tobin Crystal, Daou Roula, Szyk Jacek, Condon Ciarán
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
Mol Microbiol. 2007 Jan;63(1):127-38. doi: 10.1111/j.1365-2958.2006.05499.x.
Functional ribosomal RNAs are generated from longer precursor species in every organism known. Maturation of the 5' side of 16S rRNA in Escherichia coli is catalysed in a two-step process by the cooperative action of RNase E and RNase G. However, many bacteria lack RNase E and RNase G orthologues, raising the question as to how 16S rRNA processing occurs in these organisms. Here we show that the maturation of Bacillus subtilis 16S rRNA is also a two-step process and that the enzyme responsible for the generation of the mature 5' end is the widely distributed essential ribonuclease YkqC/RNase J1. Depletion of B. subtilis of RNase J1 results in an accumulation of 16S rRNA precursors in vivo. The precursor species are found in polysomes suggesting that they can function in translation. Mutation of the predicted catalytic site of RNase J1 abolishes both 16S rRNA processing and cell viability. Finally, purified RNase J1 can correctly mature precursor 16S rRNA assembled in 70S ribosomes, showing that its role is direct.
在已知的每一种生物中，功能性核糖体RNA都是由更长的前体产生的。大肠杆菌中16S rRNA 5'端的成熟是由核糖核酸酶E（RNase E）和核糖核酸酶G（RNase G）协同作用分两步催化完成的。然而，许多细菌缺乏RNase E和RNase G的直系同源物，这就引发了一个问题，即这些生物中的16S rRNA加工过程是如何发生的。在这里，我们表明枯草芽孢杆菌16S rRNA的成熟也是一个两步过程，并且负责产生成熟5'端的酶是广泛分布的必需核糖核酸酶YkqC/RNase J1。在体内，枯草芽孢杆菌中RNase J1的缺失会导致16S rRNA前体的积累。这些前体存在于多聚核糖体中，这表明它们可以在翻译中发挥作用。RNase J1预测催化位点的突变会消除16S rRNA的加工过程以及细胞活力。最后，纯化的RNase J1能够正确地使组装在70S核糖体中的16S rRNA前体成熟，这表明它的作用是直接的。
