Structure of a Transcribing T7 RNA Polymerase Initiation Complex
Structure of a Transcribing T7 RNA Polymerase Initiation Complex
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DOI：
10.1142/9789811215865_0035
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
G. Cheetham;T. Steitz
中科院分区：
文献类型：
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作者：
G. Cheetham;T. Steitz
T7 RNA聚合酶（T7 RNAP）起始复合物的结构被捕获转录RNA的三核苷酸从一个17碱基对的启动子DNA含有一个5-核苷酸的单链模板延伸，确定在2.4埃的分辨率。启动子的上游双链体部分的结合以与开放启动子复合物中相同的方式发生，但是单链模板被重新定位以将+4碱基置于催化活性位点。因此，在起始阶段RNA的合成导致模板在T7 RNAP的封闭活性位点口袋中的积累或“挤压”。在RNA从模板上剥离之前，只有三个碱基对的异源双链体形成。
The structure of a T7 RNA polymerase (T7 RNAP) initiation complex captured transcribing a trinucleotide of RNA from a 17–base pair promoter DNA containing a 5-nucleotide single-strand template extension was determined at a resolution of 2.4 angstroms. Binding of the upstream duplex portion of the promoter occurs in the same manner as that in the open promoter complex, but the single-stranded template is repositioned to place the +4 base at the catalytic active site. Thus, synthesis of RNA in the initiation phase leads to accumulation or “scrunching” of the template in the enclosed active site pocket of T7 RNAP. Only three base pairs of heteroduplex are formed before the RNA peels off the template.