RNA TEMPLATE-DIRECTED RNA-SYNTHESIS BY T7 RNA-POLYMERASE
RNA TEMPLATE-DIRECTED RNA-SYNTHESIS BY T7 RNA-POLYMERASE
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DOI：
10.1073/pnas.91.15.6972
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发表时间：
1994-07-19
影响因子：
11.1
通讯作者：
UHLENBECK, OC
中科院分区：
文献类型：
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作者：
CAZENAVE, C;UHLENBECK, OC
为了通过噬菌体T7 RNA聚合酶的转录终止法合成寡核糖核苷酸，产生了一种主要的转录产物，其长度比预期的要长得多。对该反应的分析表明，该产物是由最初的DNA指导的转录终止反应，随后是RNA模板指导的RNA合成所产生的。发生这种反应是因为由DNA模板合成的RNA在其3'端表现出自我互补性，因此能够形成分子内或分子间有引物的模板。在仅含有RNA模板的反应中，NTP（核苷三磷酸）的掺入速率与依赖DNA的转录相当。已经发现许多寡核糖核苷酸都会发生RNA模板指导的RNA合成，即使是那些稳定性很差的有引物的模板也是如此。在一个实例中，我们观察到一个多步延伸反应，它将寡核苷酸转化为最终产物，其长度是原始长度的两倍多。据推测，这样一个过程可能产生了一些被发现可被T7 RNA聚合酶高效复制的RNA。
In an attempt to synthesize an oligoribonucleotide by run-off transcription by bacteriophage T7 RNA polymerase, a major transcript was produced that was much longer than expected. Analysis of the reaction indicated that the product resulted from initial DNA-directed run-off transcription followed by RNA template-directed RNA synthesis. This reaction occurred because the RNA made from the DNA template displayed self-complementarity at its 3' end and therefore could form an intra- or intermolecular primed template. In reactions containing only an RNA template, the rate of incorporation of NTPs was quite comparable to DNA-dependent transcription. RNA template-directed RNA synthesis has been found to occur with a great number of oligoribonucleotides, even with primed templates that are only marginally stable. In one instance, we observed a multistep extension reaction converting the oligonucleotide into a final product longer than twice its original length. Presumably, such a process could have generated some of the RNAs found to be efficiently replicated by T7 RNA polymerase.