核小体外DNA的功能作用以及核小体在ISW2介导的染色质重塑中的进入位点
Functional role of extranucleosomal DNA and the entry site of the nucleosome in chromatin remodeling by ISW2.
作者信息
Zofall Martin, Persinger Jim, Bartholomew Blaine
机构信息
Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901-4413, USA.
出版信息
Mol Cell Biol. 2004 Nov;24(22):10047-57. doi: 10.1128/MCB.24.22.10047-10057.2004.
A minimal amount of extranucleosomal DNA was required for nucleosome mobilization by ISW2 as shown by using a photochemical histone mapping approach to analyze nucleosome movement on a set of nucleosomes with varied lengths of extranucleosomal DNA. ISW2 was ineffective in repositioning or mobilizing nucleosomes with <or=20 bp of extranucleosomal DNA. In addition, ISW2 was able to slide nucleosomes to within only 10 to 13 bp of the edge of DNA fragments. The nucleosome mobilization was promoted by extranucleosomal single-stranded DNA with modest strand preference. Gaps (10 bp) just inside the nucleosome and in the extranucleosomal DNA showed that the transfer of torsional strain (twist) into the nucleosomal DNA region was not required for mobilizing nucleosomes. However, indications are that the extranucleosomal DNA immediately adjacent to the nucleosome has an important role in the initial stage of nucleosome movement by ISW2.
通过使用光化学组蛋白定位方法分析一组具有不同长度核小体外DNA的核小体上的核小体运动，结果表明，ISW2介导的核小体移动仅需要极少量的核小体外DNA。对于核小体外DNA长度小于或等于20 bp的核小体，ISW2在重新定位或移动核小体方面无效。此外，ISW2只能将核小体滑动到距DNA片段边缘仅10至13 bp的位置。适度的链偏好表明，核小体外单链DNA可促进核小体移动。核小体内部和核小体外DNA内的缺口（10 bp）表明，核小体移动不需要将扭转应变（扭曲）转移到核小体DNA区域。然而，有迹象表明，紧邻核小体的核小体外DNA在ISW2介导的核小体运动初始阶段具有重要作用。
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