School of Biological Sciences, Chung-Ang University, Seoul, 156-756, Republic of Korea.
J Microbiol. 2011 Jun;49(3):508-11. doi: 10.1007/s12275-011-1198-7. Epub 2011 Jun 30.
In Escherichia coli, primary rRNA transcripts must be processed by a complex process in which several ribonucleases are involved in order to generate mature 16S, 23S, and 5S rRNA molecules. While it is known that RNase G, a single-stranded RNA-specific endoribonuclease encoded by the rng gene, plays an active role in the maturation of the 5'-end of 16S rRNA, its involvement in the maturation of the 5'-end of 23S rRNA remains unclear. Here we show that E. coli cells deleted for the rng gene accumulate the 23S rRNA precursor containing an extra 77 nucleotides at its mature 5'-end. In vitro cleavage assays show that RNase G cleaves synthetic RNA containing a sequence encompassing the 5'-end to 77 nucleotides upstream of mature 23S rRNA at two sites present in single-stranded regions. Our results suggest the involvement of RNase G in the processing of the 5'-region of 23S rRNA precursors.
在大肠杆菌中，初级 rRNA 转录本必须经过一个复杂的过程进行加工，在此过程中涉及几种核酶，才能生成成熟的 16S、23S 和 5S rRNA 分子。虽然已知由 rng 基因编码的单链 RNA 特异性内切核酸酶 RNase G 在 16S rRNA 5'端成熟过程中发挥积极作用，但它在 23S rRNA 5'端成熟过程中的参与仍不清楚。在这里，我们表明缺失 rng 基因的大肠杆菌细胞积累了在其成熟 5'端含有额外 77 个核苷酸的 23S rRNA 前体。体外切割实验表明，RNase G 在两个存在于单链区域的位点切割含有成熟 23S rRNA 上游 5'端至 77 个核苷酸序列的合成 RNA。我们的结果表明 RNase G 参与了 23S rRNA 前体 5'区域的加工。
