组蛋白变体 H2A.Z 可刺激模拟开关(ISWI)类 ATP 依赖性重塑酶进行染色质重塑。

Chromatin remodeling by imitation switch (ISWI) class ATP-dependent remodelers is stimulated by histone variant H2A.Z.

机构信息

Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.

出版信息

J Biol Chem. 2010 Feb 12;285(7):4645-51. doi: 10.1074/jbc.M109.072348. Epub 2009 Nov 25.

Abstract

ATP-dependent chromatin remodeling complexes rearrange nucleosomes by altering the position of DNA around the histone octamer. Although chromatin remodelers and the histone variant H2A.Z colocalize on transcriptional control regions, whether H2A.Z directly affects remodeler association or activity is unclear. We determined the relative association of remodelers with H2A.Z chromatin and tested whether replacement of H2A.Z in a nucleosome altered the activity of remodeling enzymes. Many families of remodelers showed increased association with H2A.Z chromatin, but only the ISWI family of chromatin remodelers showed stimulated activity in vitro. An acidic patch on the nucleosome surface, extended by inclusion of H2A.Z in nucleosomes and essential for viability, is required for ISWI stimulation. We conclude that H2A.Z incorporation increases nucleosome remodeling activity of the largest class of mammalian remodelers (ISWI) and that it correlates with increased association of other remodelers to chromatin. This reveals two possible modes for regulation of a remodeler by a histone variant.

摘要

ATP 依赖的染色质重塑复合物通过改变组蛋白八聚体周围 DNA 的位置来重排核小体。尽管染色质重塑因子和组蛋白变体 H2A.Z 共同定位于转录调控区域,但 H2A.Z 是否直接影响重塑因子的结合或活性尚不清楚。我们确定了重塑因子与 H2A.Z 染色质的相对结合,并测试了在核小体中替换 H2A.Z 是否改变了重塑酶的活性。许多重塑因子家族与 H2A.Z 染色质的结合增加,但只有 ISWI 家族的染色质重塑因子在体外表现出活性增强。核小体表面的酸性斑块通过在核小体中包含 H2A.Z 而延伸,对生存至关重要,这是 ISWI 刺激所必需的。我们的结论是,H2A.Z 的掺入增加了最大类哺乳动物重塑因子(ISWI)的核小体重塑活性,并且与其他重塑因子与染色质的结合增加相关。这揭示了组蛋白变体调节重塑因子的两种可能模式。

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