Evidence that Spt4, Spt5, and Spt6, control transcription elongation by RNA polymerase II in Saccharomyces cerevisiae
Evidence that Spt4, Spt5, and Spt6, control transcription elongation by RNA polymerase II in Saccharomyces cerevisiae
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DOI：
10.1101/gad.12.3.357
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发表时间：
1998-02-01
影响因子：
10.5
通讯作者：
Winston, F
中科院分区：
文献类型：
--
作者：
Hartzog, GA;Wada, T;Winston, F
先前对酿酒酵母Spt4， Spt5和Spt6蛋白的表征表明，这些蛋白作为修饰染色质结构的转录因子。在这项工作中，我们报告了新的Spt4， Spt5和Spt6的遗传和生化研究，揭示了这些因子在转录伸长中的作用。我们已经分离出SPT5的条件突变，这些突变可以通过RNA聚合酶II （Pol II）的两个最大亚基的突变以等位基因特异性的方式被抑制。引人注目的是，其中一个RNA Pol II突变体在转录延伸方面存在缺陷，而其他突变体的表型与延伸缺陷一致。此外，我们发现spt4、spt5和spt6突变体本身的表型表明体内转录延伸存在缺陷。与这些发现一致，我们发现Spt5在体内与RNA Pol II物理相关，并且已经确定了Spt5和NusG（一种直接结合RNA聚合酶的大肠杆菌转录延伸因子）之间的序列相似性区域。最后，我们发现Spt4和Spt5在一个不含Spt6的复合物中紧密结合。这些结果，连同人类Spt4-Spt5复合体作为转录延伸因子的生化鉴定（Wada et al. 1998），提供了强有力的证据，证明这些因素对体内转录延伸很重要。
Previous characterization of the Saccharomyces cerevisiae Spt4, Spt5, and Spt6 proteins suggested that these proteins act as transcription factors that modify chromatin structure. In this work, we report new genetic and biochemical studies of Spt4, Spt5, and Spt6 that reveal a role for these factors in transcription elongation. We have isolated conditional mutations in SPT5 that can be suppressed in an allele-specific manner by mutations in the two largest subunits of RNA polymerase II (Pol II). Strikingly, one of these RNA Pol II mutants is defective for transcription elongation and the others cause phenotypes consistent with an elongation defect. In addition, we show that spt4, spt5, and spt6 mutants themselves have phenotypes suggesting defects in transcription elongation in vivo. Consistent with these findings, we show that Spt5 is physically associated with RNA Pol II in vivo, and have identified a region of sequence similarity between Spt5 and NusG, an Escherichia coli transcription elongation factor that binds directly to RNA polymerase. finally, we show that Spt4 and Spt5 are tightly associated in a complex that does not contain Spt6. These results, taken together with the biochemical identification of a human Spt4-Spt5 complex as a transcription elongation factor (Wada et al. 1998), provide strong evidence that these factors are important for transcription elongation in vivo.