Initial transcription by RNA polymerase proceeds through a DNA-scrunching mechanism
Initial transcription by RNA polymerase proceeds through a DNA-scrunching mechanism
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DOI：
10.1126/science.1131399
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发表时间：
2006-11-17
期刊：
影响因子：
56.9
通讯作者：
Ebright, Richard H.
中科院分区：
文献类型：
--
作者：
Kapanidis, Achillefs N.;Margeat, Emmanuel;Ebright, Richard H.
利用荧光共振能量转移来监测失败启动的转录起始复合体的单分子内的距离，我们发现起始转录是通过一种“挤压”机制进行的，在该机制中，RNA聚合酶(RNAP)保持固定在启动子DNA上，并将下游DNA拉入自身并越过其活性中心。我们进一步表明，在初始转录中RNAP活性中心移位的假设替代机制，包括RNAP相对于DNA的“瞬时偏移”或RNAP相对于DNA的“蠕动”，没有发生。结果支持一个模型，即在初始转录过程中形成一个具有DNA解卷应力和DNA紧致应力的应激中间产物，并在启动子逃逸过程中利用累积应力来驱动RNAP与启动子DNA之间以及RNAP与起始因子之间相互作用的破坏。
Using fluorescence resonance energy transfer to monitor distances within single molecules of abortively initiating transcription initiation complexes, we show that initial transcription proceeds through a "scrunching'' mechanism, in which RNA polymerase ( RNAP) remains fixed on promoter DNA and pulls downstream DNA into itself and past its active center. We show further that putative alternative mechanisms for RNAP active-center translocation in initial transcription, involving "transient excursions" of RNAP relative to DNA or "inchworming" of RNAP relative to DNA, do not occur. The results support a model in which a stressed intermediate, with DNA-unwinding stress and DNA-compaction stress, is formed during initial transcription, and in which accumulated stress is used to drive breakage of interactions between RNAP and promoter DNA and between RNAP and initiation factors during promoter escape.