Becht Dustin C, Biswas Soumi, Xu Chenxi, Xuan Hongwen, Khalil Moustafa, Cai Ling, Musselman Catherine A, Liu Xin, Affar El Bachir, Shi Xiaobing, Wang Gang Greg, Kutateladze Tatiana G
Department of Pharmacology, University of Colorado School of Medicine, Aurora CO 80045, U.S.A.
Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham NC 27710, U.S.A.
Biochem J. 2025 Jul 2;482(13):955-968. doi: 10.1042/BCJ20253037.
The H3K27me-specific methyltransferase enhancer of zeste homologue 2 (EZH2) is the catalytic subunit of the repressive complex Polycomb repressive complex 2. EZH2 is typically implicated in transcriptional silencing, but it can also activate gene expression. Here, we show that EZH2 contains three adjacent transactivation domains (EZH2TAD) that are recognized by the TAZ2 domain of the transcriptional coactivator and acetyltransferase p300 (p300TAZ2). Binding interfaces identified by chemical shift perturbations in NMR experiments, measurements of binding affinities, and analysis of the complex formation by mass photometry demonstrate that each EZH2TAD can be concomitantly bound by a separate p300TAZ2. Interaction of EZH2TADs with p300TAZ2 stimulates H3K18- and H3K27-specific acetyltransferase activity of p300. We show that in 22Rv1 prostate cancer cells, EZH2 occupies a large set of gene loci lacking H3K27me3, and these non-canonical genomic sites are instead co-occupied by p300, RNA Polymerase II and BRD4 and are rich in histone marks associated with transcriptional activation. Our findings shed light on the potential basis for such a high degree of genetic co-localization through the direct association of p300TAZ2 with EZH2TADs.
zeste 同源物 2（EZH2）的 H3K27me 特异性甲基转移酶增强子是抑制复合物多梳抑制复合物 2 的催化亚基。EZH2 通常与转录沉默有关，但它也可以激活基因表达。在这里，我们表明 EZH2 包含三个相邻的反式激活结构域（EZH2TAD），它们被转录共激活因子和乙酰转移酶 p300（p300TAZ2）的 TAZ2 结构域识别。通过核磁共振实验中的化学位移扰动、结合亲和力测量以及质量光度法对复合物形成的分析确定的结合界面表明，每个 EZH2TAD 都可以被一个单独的 p300TAZ2 同时结合。EZH2TAD 与 p300TAZ2 的相互作用刺激了 p300 的 H3K18 和 H3K27 特异性乙酰转移酶活性。我们表明，在 22Rv1 前列腺癌细胞中，EZH2 占据了大量缺乏 H3K27me3 的基因位点，这些非经典基因组位点反而被 p300、RNA 聚合酶 II 和 BRD4 共同占据，并且富含与转录激活相关的组蛋白标记。我们的研究结果通过 p300TAZ2 与 EZH2TAD 的直接关联揭示了这种高度基因共定位的潜在基础。
