The mechanism of intrinsic transcription termination
The mechanism of intrinsic transcription termination
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DOI：
10.1016/s1097-2765(00)80477-3
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发表时间：
1999-04-01
期刊：
影响因子：
16
通讯作者：
Nudler, E
中科院分区：
文献类型：
--
作者：
Gusarov, I;Nudler, E
在细菌中，一种内在的转录终止信号在RNA中表现为一个发夹结构，其后在3'末端大约有八个尿苷（U串）。这种信号导致三元延伸复合物（TEC）迅速解离为RNA、DNA和一种RNA聚合酶。我们证明发夹结构通过削弱将TEC维系在一起的RNA - DNA杂合结合位点以及RNA结合位点中的相互作用，使TEC失活，进而使其不稳定。发夹结构的形成仅限于TEC到达终止点的时刻，并且依赖于发夹茎部之后4到5个杂合碱基对的解链。U串在终止点诱导的暂停至关重要，为发夹结构的形成提供了额外的时间。这些结果解释了终止的机制，并有助于理解细胞因子如何调节这一过程。
In bacteria, an intrinsic transcription termination signal appears in RNA as a hairpin followed by approximately eight uridines (U stretch) at the 3' terminus. This signal leads to rapid dissociation of the ternary elongation complex (TEC) into RNA, DNA, and an RNA polymerase. We demonstrate that the hairpin inactivates and then destabilizes TEC by weakening interactions in the RNA-DNA hybrid-binding site and the RNA-binding site that hold TEC together. Formation of the hairpin is restricted to the moment when TEC reaches the point of termination and depends upon melting of four to five hybrid base pairs that follow the hairpin's stem. The U stretch-induced pausing at the point of termination is crucial, providing additional time for hairpin formation. These results explain the mechanism of termination and aid in understanding of how cellular factors modulate this process.