Dang Weiwei, Kagalwala Mohamedi N, Bartholomew Blaine
Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901-4413, USA.
J Biol Chem. 2007 Jul 6;282(27):19418-25. doi: 10.1074/jbc.M700640200. Epub 2007 May 9.
Histone fold proteins Dpb4 and Dls1 are components of the yeast ISW2 chromatin remodeling complex that resemble the smaller subunits of the CHRAC (Chromatin Accessibility Complex) complex found in Drosophila and humans. DNA photoaffinity labeling found that the Dpb4 subunit contacts extranucleosomal DNA 37-53 bp away from the entry/exit site of the nucleosome. Binding of Dpb4 to Isw2 and Itc2, the two largest subunits of ISW2, was found to require Dls1. Even after remodeling and nucleosome movement, Dpb4 tends to remain bound to its original binding site and likely serves as an anchor point for ISW2 on DNA. In vitro, only minor differences can be detected in the nucleosome binding and mobilization properties of ISW2 with or without Dpb4 and Dls1. Changes in the contacts of the largest subunit Itc1 with extranucleosomal DNA have, however, been found upon deletion of the Dpb4 and Dls1 dimer that may affect the nucleosome spacing properties of ISW2.
组蛋白折叠蛋白Dpb4和Dls1是酵母ISW2染色质重塑复合物的组成部分，它们类似于在果蝇和人类中发现的染色质可及性复合物（CHRAC）复合物的较小亚基。DNA光亲和标记发现，Dpb4亚基与核小体进入/退出位点37 - 53 bp处的核小体外DNA接触。发现Dpb4与ISW2的两个最大亚基Isw2和Itc2结合需要Dls1。即使在重塑和核小体移动后，Dpb4仍倾向于保持与其原始结合位点结合，并且可能作为ISW2在DNA上的锚定点。在体外，有或没有Dpb4和Dls1的ISW2在核小体结合和移动特性方面仅能检测到微小差异。然而，在缺失Dpb4和Dls1二聚体后，发现最大亚基Itc1与核小体外DNA的接触发生了变化，这可能会影响ISW2的核小体间距特性。
