Phosphorylation of the RNA polymerase II C-terminal domain by TFIIH kinase is not essential for transcription of Saccharomyces cerevisiae genome
Phosphorylation of the RNA polymerase II C-terminal domain by TFIIH kinase is not essential for transcription of Saccharomyces cerevisiae genome
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DOI：
10.1073/pnas.0903642106
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发表时间：
2009-08-25
影响因子：
11.1
通讯作者：
Lee, Dong-ki
中科院分区：
文献类型：
--
作者：
Hong, Sun Woo;Hong, Seong Min;Lee, Dong-ki
TFIIH激酶对RNA聚合酶II (Pol II) c端结构域的Ser-5磷酸化与mRNA合成的关键步骤有关，如Pol II启动子逃逸和mRNA 5'-capping。然而，TFIIH激酶在Pol II转录中的一般要求和确切作用仍不清楚。在这里，我们使用化学遗传学方法来表明，对于大多数发酵菌基因，酵母TFIIH激酶的特异性抑制导致mRNA水平和Ser-5 c -末端结构域磷酸化的显著降低。令人惊讶的是，抑制TFIIH激酶活性仅部分影响Pol II密度和Ser-2磷酸化水平。mRNA水平和Pol II密度之间的差异归因于缺陷的5'-capping，这导致mRNA的不稳定。因此，与目前的看法相反，我们的研究强烈指出TFIIH激酶在Pol II转录中的作用较小，而在出芽酵母的mRNA capping中起着更重要的作用。
Ser-5 phosphorylation of the RNA polymerase II (Pol II) C-terminal domain by TFIIH kinase has been implicated in critical steps in mRNA synthesis, such as Pol II promoter escape and mRNA 5'-capping. However, the general requirement and precise role of TFIIH kinase in Pol II transcription still remain elusive. Here we use a chemical genetics approach to show that, for a majority of budding-yeast genes, specific inhibition of the yeast TFIIH kinase results in a dramatic reduction in both mRNA level and Ser-5 C-terminal domain phosphorylation. Surprisingly, inhibition of TFIIH kinase activity only partially affected both Pol II density and Ser-2 phosphorylation level. The discrepancy between mRNA level and Pol II density is attributed to the defective 5'-capping, which results in the destabilization of mRNAs. Therefore, contrary to the current belief, our study points strongly toward a minor role of TFIIH kinase in Pol II transcription, and a more significant role in mRNA capping in budding yeast.