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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Architecture of initiation-competent 12-subunit RNA polymerase II
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Architecture of initiation-competent 12-subunit RNA polymerase II

机译：具有启动能力的12亚基RNA聚合酶II的体系结构

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摘要

RNA polymerase (Pol) II consists of a 10-polypeptide catalytic core and the two-subunit Rpb4/7 complex that is required for transcription initiation. Previous structures of the Pol II core revealed a "clamp," which binds the DNA template strand via three "switch regions," and a flexible "linker" to the C-terminal repeat domain (CTD). Here we derived a model of the complete Pol II by fitting structures of the core and Rpb4/7 to a 4.2-Angstrom crystallographic electron density map. Rpb4/7 protrudes from the polymerase "upstream face," on which initiation factors assemble for promoter DNA loading. Rpb7 forms a wedge between the clamp and the linker, restricting the clamp to a closed position. The wedge allosterically prevents entry of the promoter DNA duplex into the active center cleft and induces in two switch regions a conformation poised for template-strand binding. Interaction of Rpb4/7 with the linker explains Rpb4-mediated recruitment of the CTD phosphatase to the CTD during Pol II recycling. The core-Rpb7 interaction and some functions of Rpb4/7 are apparently conserved in all eukaryotic and archaeal RNA polymerases but not in the bacterial enzyme. [References: 54]
机译：RNA聚合酶（Pol）II由10个多肽催化核心和转录起始所需的两个亚基Rpb4 / 7复合体组成。 Pol II核心的先前结构显示了一个“钳位”，该钳位通过三个“开关区”与DNA模板链结合，并在C末端重复域（CTD）上连接了一个灵活的“接头”。在这里，我们通过将核和Rpb4 / 7的结构拟合到4.2埃晶体电子密度图上，得出了完整Pol II的模型。 Rpb4 / 7从聚合酶“上游面”突出，在其上聚集启动因子以装载启动子DNA。 Rpb7在夹具和连接器之间形成楔形，从而将夹具限制在关闭位置。楔形变构地防止启动子DNA双链体进入活性中心裂口，并在两个开关区域中诱导蓄势模板链结合的构象。 Rpb4 / 7与接头的相互作用说明了Pol II回收过程中Rpb4介导的CTD磷酸酶募集到CTD。 Rpb4 / 7的核心-Rpb7相互作用和某些功能显然在所有真核和古细菌RNA聚合酶中都保守，但在细菌酶中却不保守。 [参考：54]

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