A targeted histone acetyltransferase can create a sizable region of hyperacetylated chromatin and counteract the propagation of transcriptionally silent chromatin.
A targeted histone acetyltransferase can create a sizable region of hyperacetylated chromatin and counteract the propagation of transcriptionally silent chromatin.
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发表时间：
2003-09
期刊：
影响因子：
3.3
通讯作者：
Y. Chiu;Qun Yu;J. Sandmeier;X. Bi
中科院分区：
文献类型：
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作者：
Y. Chiu;Qun Yu;J. Sandmeier;X. Bi
转录沉默的染色质与组蛋白乙酰化减少有关，其增殖依赖于组蛋白去乙酰化酶促进的组蛋白低乙酰化。我们表明，拴系组蛋白乙酰转移酶（HAT）Esa1p或Gcn5p创建一个片段的超乙酰化染色质，是至少2.6 kb的大小和抵消转录沉默，从酵母中的沉默者发出。Esa1p和Gcn5p甚至在它们靶向启动子下游1.7 kb和距离沉默子>2.0 kb时也会抵消URA3沉默。靶向HAT的抗沉默作用通过增加靶向位点的数量而加强，但被增强沉默的事件削弱。系留的HAT也可以抵消端粒沉默。通过消除其HAT活性的突变或通过缺失编码含Gcn5p的HAT复合物的结构组分的ADA 2基因来消除Gcn5p的抗沉默作用。这些结果表明，拴系的HAT复合物可以产生相当大的组蛋白超乙酰化区域，并作为侵入抑制性染色质的屏障。
Transcriptionally silent chromatin is associated with reduced histone acetylation and its propagation depends on histone hypoacetylation promoted by histone deacetylases. We show that tethered histone acetyltransferase (HAT) Esa1p or Gcn5p creates a segment of hyperacetylated chromatin that is at least 2.6 kb in size and counteracts transcriptional silencing that emanates from a silencer in yeast. Esa1p and Gcn5p counteract URA3 silencing even when they are targeted 1.7 kb downstream of the promoter and >2.0 kb from the silencer. The anti-silencing effect of a targeted HAT is strengthened by increasing the number of targeting sites, but impaired by events that enhance silencing. A tethered HAT can also counteract telomeric silencing. The anti-silencing effect of Gcn5p is abolished by a mutation that eliminated its HAT activity or by deleting the ADA2 gene encoding a structural component of Gcn5p-containing HAT complexes. These results demonstrate that a tethered HAT complex can create a sizable region of histone hyperacetylation and serve as a barrier to encroaching repressive chromatin.