Targeting histone deacetylase complexes via KRAB-zinc finger proteins:: the PHD and bromodomains of KAP-1 form a cooperative unit that recruits a novel isoform of the Mi-2α subunit of NuRD
Targeting histone deacetylase complexes via KRAB-zinc finger proteins:: the PHD and bromodomains of KAP-1 form a cooperative unit that recruits a novel isoform of the Mi-2α subunit of NuRD
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DOI：
10.1101/gad.869501
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发表时间：
2001-02-15
影响因子：
10.5
通讯作者：
Rauscher, FJ
中科院分区：
文献类型：
--
作者：
Schultz, DC;Friedman, JR;Rauscher, FJ
含有组蛋白脱乙酰酶和ATPase活性的大分子复合体调节染色质的动力学，对真核生物中转录基因的沉默起着至关重要的作用。针对特定位点的这些组装的机制还没有被很好地理解。我们发现辅阻遏子KAP-1通过其PHD(植物同源结构域)和溴结构域将Kruppel相关盒(KRAB)锌指蛋白(ZFP)超家族连接到NuRD复合体。我们证明了KAP-1的串联PHD指和溴域，一种经常在辅因子蛋白中发现但功能不明确的排列，形成了转录抑制所需的合作单元。替换高度相关的PHD指或溴结构域不能恢复抑制活性，这表明它们的合作功能具有高度的特异性。此外，在溴域或PhD手指中的单一氨基酸替换，包括那些模仿hATRX PhD手指致病突变的替换，取消了抑制。对这种抑制功能的效应物的搜索发现了Mi-2α蛋白的肚脐异构体，它是NuRD复合体的一个组成部分。内源性KAP-1与Mi-2α和NuRD的其他成分相关，KAP-1介导的沉默需要与NuRD和HDAC活性相关。这些数据表明，KRAB-ZFP抑制物超家族的功能是针对体内特定基因启动子的NuRD复合体的组蛋白去乙酰化酶和染色质重塑活性。
Macromolecular complexes containing histone deacetylase and ATPase activities regulate chromatin dynamics and are vitally responsible for transcriptional gene silencing in eukaryotes. The mechanisms that target these assemblies to specific loci are not as well understood. We show that the corepressor KAP-1, via its PHD (plant homeodomain) and bromodomain, links the superfamily of Kruppel associated box (KRAB) zinc finger proteins (ZFP) to the NuRD complex. We demonstrate that the tandem PHD finger and bromodomain of KAP-1, an arrangement often found in cofactor proteins but functionally ill-defined, form a cooperative unit that is required for transcriptional repression. Substitution of highly related PHD fingers or bromodomains failed to restore repression activity, suggesting high specificity in their cooperative function. Moreover, single amino acid substitutions in either the bromodomain or PHD finger, including ones that mimic disease-causing mutations in the hATRX PHD finger, abolish repression. A search for effecters of this repression function yielded a navel isoform of the Mi-2 alpha protein, an integral component of the NuRD complex. Endogenous KAP-1 is associated with Mi-2 alpha and other components of NuRD, and KAP-1-mediated silencing requires association with NuRD and HDAC activity. These data suggest the KRAB-ZFP superfamily of repressors functions to target the histone deacetylase and chromatin remodeling activities of the NuRD complex to specific gene promoters in vivo.