Siegel R W, Bellon L, Beigelman L, Kao C C
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11613-8. doi: 10.1073/pnas.95.20.11613.
RNAs 33 nucleotides in length can direct accurate initiation of subgenomic RNA synthesis by the brome mosaic virus RNA-dependent RNA polymerase (RdRp), provided that the native sequences are maintained at five positions: -17, -14, -13, -11, and the +1 initiation site. The functional groups in the bases of these essential nucleotides required to interact with RdRp were examined by using chemically synthesized RNAs containing base analogs at each of the five positions. Analysis using a template competition assay revealed that the mode of recognition for the initiation nucleotide (+1) is distinct from that of the other essential nucleotides in the promoter. Competition experiments also determined that three template nucleotides are sufficient for stable interaction with RdRp. These results identify base moieties in the brome mosaic virus subgenomic promoter required for efficient RNA synthesis and support the hypothesis that the recognition of a RNA promoter by a viral RdRp is analogous to the recognition of DNA promoters by DNA-dependent RNA polymerases.
长度为33个核苷酸的RNA可以指导雀麦花叶病毒RNA依赖性RNA聚合酶（RdRp）准确启动亚基因组RNA合成，前提是天然序列在五个位置保持不变：-17、-14、-13、-11以及+1起始位点。通过使用在这五个位置的每一个都含有碱基类似物的化学合成RNA，研究了与RdRp相互作用所需的这些必需核苷酸的碱基中的官能团。使用模板竞争试验进行的分析表明，起始核苷酸（+1）的识别模式与启动子中其他必需核苷酸的识别模式不同。竞争实验还确定，三个模板核苷酸足以与RdRp进行稳定相互作用。这些结果确定了雀麦花叶病毒亚基因组启动子中有效RNA合成所需的碱基部分，并支持这样一种假设，即病毒RdRp对RNA启动子的识别类似于依赖DNA的RNA聚合酶对DNA启动子的识别。
