Ferreira Helder, Flaus Andrew, Owen-Hughes Tom
Division of Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
J Mol Biol. 2007 Nov 30;374(3):563-79. doi: 10.1016/j.jmb.2007.09.059. Epub 2007 Sep 26.
Alteration of chromatin structure by chromatin modifying and remodelling activities is a key stage in the regulation of many nuclear processes. These activities are frequently interlinked, and many chromatin remodelling enzymes contain motifs that recognise modified histones. Here we adopt a peptide ligation strategy to generate specifically modified chromatin templates and used these to study the interaction of the Chd1, Isw2 and RSC remodelling complexes with differentially acetylated nucleosomes. Specific patterns of histone acetylation are found to alter the rate of chromatin remodelling in different ways. For example, histone H3 lysine 14 acetylation acts to increase recruitment of the RSC complex to nucleosomes. However, histone H4 tetra-acetylation alters the spectrum of remodelled products generated by increasing octamer transfer in trans. In contrast, histone H4 tetra-acetylation was also found to reduce the activity of the Chd1 and Isw2 remodelling enzymes by reducing catalytic turnover without affecting recruitment. These observations illustrate a range of different means by which modifications to histones can influence the action of remodelling enzymes.
染色质修饰和重塑活动对染色质结构的改变是许多核过程调控中的关键阶段。这些活动常常相互关联,许多染色质重塑酶含有识别修饰组蛋白的基序。在这里,我们采用肽连接策略来生成特异性修饰的染色质模板,并利用这些模板研究Chd1、Isw2和RSC重塑复合物与不同乙酰化核小体的相互作用。发现组蛋白乙酰化的特定模式以不同方式改变染色质重塑的速率。例如,组蛋白H3赖氨酸14乙酰化作用是增加RSC复合物向核小体的募集。然而,组蛋白H4四乙酰化通过增加反式八聚体转移来改变重塑产物的谱。相反,还发现组蛋白H4四乙酰化通过降低催化周转率而不影响募集来降低Chd1和Isw2重塑酶的活性。这些观察结果说明了组蛋白修饰影响重塑酶作用的一系列不同方式。