The nature of the nucleosomal barrier to transcription: Direct observation of paused intermediates by electron cryomicroscopy
The nature of the nucleosomal barrier to transcription: Direct observation of paused intermediates by electron cryomicroscopy
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DOI：
10.1016/s1097-2765(00)80339-1
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发表时间：
1999-09-01
期刊：
影响因子：
16
通讯作者：
Woodcock, CL
中科院分区：
文献类型：
--
作者：
Bednar, J;Studitsky, VM;Woodcock, CL
转录SP 6 RNA聚合酶被逮捕在核小体核心的独特位置，并使用生化方法和电子冷冻显微镜的复合物进行分析。当聚合酶进入核小体时，它会破坏延伸复合物后面和前面约20 bp的DNA-组蛋白相互作用。聚合酶进入核小体30-40个碱基对后，观察到两个中间体。在一种情况下，只有聚合酶前面的DNA与八聚体重新结合。在另一种情况下，酶前后的DNA都重新结合。这些中间体对延伸形成障碍。当聚合酶接近核小体二联体时，它取代八聚体，八聚体被转移到启动子近端DNA。
Transcribing SP6 RNA polymerase was arrested at unique positions in the nucleosome core, and the complexes were analyzed using biochemical methods and electron cryomicroscopy. As the polymerase enters the nucleosome, it disrupts DNA-histone interactions behind and up to similar to 20 bp ahead of the elongation complex. After the polymerase proceeds 30-40 bp into the nucleosome, two intermediates are observed. In one, only the DNA ahead of the polymerase; reassociates with the octamer. In the other, DNA both ahead of and behind the enzyme reassociates. These intermediates present a barrier to elongation. When the polymerase approaches the nucleosome dyad, it displaces the octamer, which is transferred to promoter-proximal DNA.