The ZZ domain of p300 mediates specificity of the adjacent HAT domain for histone H3

Human p300 is a transcriptional co-activator and a major acetyltransferase that acetylates histones and other proteins facilitating gene transcription. The activity of p300 relies on the fine-tuned interactome that involves a dozen p300 domains and hundreds of binding partners and links p300 to a wide range of vital signaling events. Here, we report on a novel function of the ZZ-type zinc finger (ZZ) of p300 as a reader of histone H3. We show that the ZZ domain and acetyllysine recognizing bromodomain (BD) of p300 play critical roles in modulating p300 enzymatic activity and its association with chromatin. Acetyllysine binding of BD is essential for acetylation of histones H3 and H4, whereas interaction of the ZZ domain with H3 promotes selective acetylation of histone H3K27 and H3K18. Overall design: ChIP-seq of Flag-p300, H3K27ac, H3K18ac were applied in human H1299 cells stably expressing WT or mutant (N1671A/D1690A) p300-BRPHZT fragment and control vector (V).

人源p300是一种转录共激活因子（transcriptional co-activator），同时亦是一类主要的乙酰转移酶（acetyltransferase），可催化组蛋白（histones）及其他蛋白的乙酰化修饰，进而促进基因转录（gene transcription）。p300的活性依赖于一套精细调控的相互作用组（interactome）：该相互作用组包含十余种p300结构域与数百个结合伴侣，将p300与一系列关键信号事件相连接。本研究首次报道了p300的ZZ型锌指结构域（ZZ-type zinc finger, ZZ）作为组蛋白H3识别结构域的全新功能。研究表明，p300的ZZ结构域与识别乙酰赖氨酸（acetyllysine）的溴结构域（bromodomain, BD）在调控p300酶活性及其与染色质（chromatin）的结合过程中发挥关键作用。其中，溴结构域的乙酰赖氨酸结合活性对组蛋白H3与H4的乙酰化修饰至关重要，而ZZ结构域与H3的相互作用则可促进组蛋白H3K27与H3K18位点的选择性乙酰化。实验整体设计：在稳定表达野生型（wild type, WT）或突变型（N1671A/D1690A）p300-BRPHZT片段的人H1299细胞及空载对照载体（V）中，分别对Flag-p300、乙酰化组蛋白H3K27（H3K27ac）、乙酰化组蛋白H3K18（H3K18ac）进行染色质免疫共沉淀测序（ChIP-seq）。