Structure of a T7 RNA polymerase elongation complex at 2.9Å resolution
Structure of a T7 RNA polymerase elongation complex at 2.9Å resolution
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DOI：
10.1038/nature01129
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发表时间：
2002-11-07
期刊：
影响因子：
64.8
通讯作者：
Yokoyama, S
中科院分区：
文献类型：
--
作者：
Tahirov, TH;Temiakov, D;Yokoyama, S
单亚基噬菌体T7 RNA聚合酶以与细菌和真核多亚基酶相同的方式进行转录循环。在这里，我们报告的晶体结构的T7 RNA聚合酶延伸复合物，这表明，纳入一个8碱基对RNA-DNA杂交到活性位点的酶诱导显着重排的氨基末端结构域。这种重排涉及约130个残基的交替折叠和稳定核心亚结构域的显著重定向（约130度旋转），导致提供稳定转录延伸所需元件的结构。在酶表面形成一个很大的开口，可能是RNA的出口通路，RNA-DNA杂交体完全被埋在新形成的深蛋白质空腔中。下游DNA的10个碱基对的结合主要通过长距离静电相互作用来稳定。该结构暗示了转录周期各个阶段的合理机制，并揭示了与多亚基RNA聚合酶的重要结构相似性。
The single-subunit bacteriophage T7 RNA polymerase carries out the transcription cycle in an identical manner to that of bacterial and eukaryotic multisubunit enzymes. Here we report the crystal structure of a T7 RNA polymerase elongation complex, which shows that incorporation of an 8-base-pair RNA-DNA hybrid into the active site of the enzyme induces a marked rearrangement of the amino-terminal domain. This rearrangement involves alternative folding of about 130 residues and a marked reorientation (about 130degrees rotation) of a stable core subdomain, resulting in a structure that provides elements required for stable transcription elongation. A wide opening on the enzyme surface that is probably an RNA exit pathway is formed, and the RNA-DNA hybrid is completely buried in a newly formed, deep protein cavity. Binding of 10 base pairs of downstream DNA is stabilized mostly by long-distance electrostatic interactions. The structure implies plausible mechanisms for the various phases of the transcription cycle, and reveals important structural similarities with the multisubunit RNA polymerases.