New model for the yeast RNA polymerase I transcription cycle
New model for the yeast RNA polymerase I transcription cycle
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DOI：
10.1128/mcb.21.15.4847-4855.2001
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发表时间：
2001-08-01
影响因子：
5.3
通讯作者：
Reeder, RH
中科院分区：
文献类型：
--
作者：
Aprikian, P;Moorefield, B;Reeder, RH
使用固定化模板分析，我们观察到两个步骤在装配的酵母RNA聚合酶I（Pol I）preinitiation复合物：稳定结合的上游激活因子（UAF），然后招募的POLI-RRN 3 P和核心因子（CF）。Pol I是CF与启动子稳定结合所必需的，并且可以在Rrn 3 p不存在的情况下被募集。在转录起始时，Pol I-Rrn 3 p和CF从启动子解离，而UAF保留在后面。这些发现支持了一种新的模型，其中Pol I基础机制在每一轮转录中启动子的开启和关闭循环。该模型解释了先前的观察结果，即rRNA合成可能通过调节启动子可及性和聚合酶活性来控制。
Using an immobilized template assay, we observed two steps in assembly of the yeast RNA polymerase I (Pol I) preinitiation complex: stable binding of upstream activating factor (UAF) followed by recruitment of pol I-Rrn3p and core factor (CF). Pol I is required for stable association of CF with the promoter and can be recruited in the absence of Rrn3p. Upon transcription initiation, Pol I-Rrn3p and CF dissociate from the promoter while UAF remains behind. These findings support a novel model in which the Pol I basal machinery cycles on and off the promoter with each round of transcription. This model accounts for previous observations that rRNA synthesis may be controlled by regulating both promoter accessibility and polymerase activity.