Drosophila ELL is associated with actively elongating RNA polymerase II on transcriptionally active sites in vivo
Drosophila ELL is associated with actively elongating RNA polymerase II on transcriptionally active sites in vivo
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DOI：
10.1093/emboj/20.21.6104
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发表时间：
2001-11-01
期刊：
影响因子：
11.4
通讯作者：
Shilatifard, A
中科院分区：
文献类型：
--
作者：
Gerber, M;Ma, JY;Shilatifard, A
一些因子已经被生化表征，其基础是它们能够提高由多蛋白复杂RNA聚合酶II(POL II)催化的总转录延伸速度。其中，ELL家族的延伸因子已被证明通过抑制暂时性停顿来提高体外转录延伸的催化速率。这类伸长因子的几个基本生物学方面尚不清楚。我们克隆了果蝇同源基因(DELL)，以测试ELL家族蛋白在体内是否与延长的POL II相关。在此，我们报道了DELL是一种核蛋白，和它的哺乳动物同源物一样，在体外可以提高Pol II的转录延伸催化速率。有趣的是，我们发现戴尔广泛地与Pol II的磷酸化、活性伸长形式共同定位在果蝇多线染色体上转录活跃的位置。此外，戴尔已从正常情况下广泛分布在多烯上的分布模式重新定位到热冲击时转录活性极低的泡芙部位。这一观察结果表明，戴尔在细胞中的局部化是一种动态模式，这是Pol II一般延伸率的预测特征。我们还证明了戴尔与POL II在物理上相互作用。我们的结果有力地表明，戴尔在体内与延长的RNA聚合酶II起作用。
Several factors have been biochemically characterized based on their ability to increase the overall rate of transcription elongation catalyzed by the multiprotein complex RNA polymerase II (Pol II). Among these, the ELL family of elongation factors has been shown to increase the catalytic rate of transcription elongation in vitro by suppressing transient pausing. Several fundamental biological aspects of this class of elongation factors are not known. We have cloned the Drosophila homolog (dELL) in order to test whether ELL family proteins are actually associated with the elongating Pol II in vivo. Here we report that dELL is a nuclear protein, which, like its mammalian homologs, can increase the catalytic rate of transcription elongation by Pol II in vitro. Interestingly, we find that dELL co-localizes extensively with the phosphorylated, actively elongating form of Pol II at transcriptionally active sites on Drosophila polytene chromosomes. Furthermore, dELL is relocalized from a widespread distribution pattern on polytenes under normal conditions to very few transcriptionally active puff sites upon heat shock. This observation indicates a dynamic pattern of localization of dELL in cells, which is a predicted characteristic of a Pol II general elongation factor. We also demonstrate that dELL physically interacts with Pol II. Our results strongly suggest that dELL functions with elongating RNA polymerase II in vivo.