Misincorporation by RNA polymerase is a major source of transcription pausing in vivo.
Misincorporation by RNA polymerase is a major source of transcription pausing in vivo.
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DOI：
10.1093/nar/gkw969
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发表时间：
2017-02-17
影响因子：
14.9
通讯作者：
Zenkin N
中科院分区：
文献类型：
--
作者：
James K;Gamba P;Cockell SJ;Zenkin N
根据最终产物RNA中的错误估计转录错误率为10−3-10−5。我们分析了来自大肠杆菌和酿酒酵母中所有活跃转录延伸复合物（EC）的新生RNA的保真度，发现野生型细胞中所有EC的1-3%和缺乏校对因子的细胞中所有EC的5-7%实际上是错误掺入的复合物。除了一些序列依赖性热点，大多数错配相对随机地分布。在热点处的错误并入似乎不会受到暂停的刺激。由于错误掺入导致转录由于回溯而强烈暂停，我们的研究结果表明，错误掺入可能是转录暂停的主要来源，并导致与其他RNA聚合酶和细菌和真核生物中的复制发生冲突。这一观察结果意味着，物理分辨率的错误合并的复合物可能是主要功能的校对因素GRE和TFIIS。虽然细菌和真核生物之间的错误掺入机制似乎是保守的，但结果表明存在细菌特异性机制以减少蛋白质编码区的错误掺入。转录保真度，人类疾病和遗传相同细胞中的表型变异性之间的联系可以通过错误掺入复合物的积累来解释，而不是成熟RNA中的错误。
The transcription error rate estimated from mistakes in end product RNAs is 10−3–10−5. We analyzed the fidelity of nascent RNAs from all actively transcribing elongation complexes (ECs) in Escherichia coli and Saccharomyces cerevisiae and found that 1–3% of all ECs in wild-type cells, and 5–7% of all ECs in cells lacking proofreading factors are, in fact, misincorporated complexes. With the exception of a number of sequence-dependent hotspots, most misincorporations are distributed relatively randomly. Misincorporation at hotspots does not appear to be stimulated by pausing. Since misincorporation leads to a strong pause of transcription due to backtracking, our findings indicate that misincorporation could be a major source of transcriptional pausing and lead to conflicts with other RNA polymerases and replication in bacteria and eukaryotes. This observation implies that physical resolution of misincorporated complexes may be the main function of the proofreading factors Gre and TFIIS. Although misincorporation mechanisms between bacteria and eukaryotes appear to be conserved, the results suggest the existence of a bacteria-specific mechanism(s) for reducing misincorporation in protein-coding regions. The links between transcription fidelity, human disease, and phenotypic variability in genetically-identical cells can be explained by the accumulation of misincorporated complexes, rather than mistakes in mature RNA.