Knezetic J A, Jacob G A, Luse D S
Department of Biochemistry and Molecular Biology, University of Cincinnati College of Medicine, Ohio 45267-0522.
Mol Cell Biol. 1988 Aug;8(8):3114-21. doi: 10.1128/mcb.8.8.3114-3121.1988.
We have previously shown that assembly of nucleosomes on the DNA template blocks transcription initiation by RNA polymerase II in vitro. In the studies reported here, we demonstrate that assembly of a complete RNA polymerase II preinitiation complex before nucleosome assembly results in nucleosomal templates which support initiation in vitro as efficiently as naked DNA. Control experiments prove that our observations are not the result of slow displacement of nucleosomes by the transcription machinery during chromatin assembly, nor are they an artifact of inefficient nucleosome deposition on templates already bearing an RNA polymerase. Thus, the RNA polymerase II preinitiation complex appears to be resistant to disruption by subsequent nucleosome assembly.
我们之前已经表明，在体外，核小体在DNA模板上的组装会阻碍RNA聚合酶II的转录起始。在本文报道的研究中，我们证明在核小体组装之前组装完整的RNA聚合酶II起始前复合物会产生核小体模板，其在体外支持起始的效率与裸DNA一样高。对照实验证明，我们的观察结果不是染色质组装过程中转录机制缓慢取代核小体的结果，也不是核小体在已经带有RNA聚合酶的模板上低效沉积的假象。因此，RNA聚合酶II起始前复合物似乎对随后的核小体组装具有抗性。
