The lysine histone demethylase KDM4B is overexpressed in several types of cancers and plays dual roles in genome stability maintenance. Although KDM4B is able to recognize several histone methylations, the underlying molecular mechanism is still unknown. In this study, we purified the KDM4B chromatin-associated hybrid tudor domains (HTDs) and plant home domains (PHDs) and performed the pull-down assay to screen the tri-methyl modified histone peptides that could be efficiently recognized by KDM4B. Our results showed that both HTD alone and the combination of HTD and PHD were able to specifically bind to H3K4me3 and H4K20me3. Because H4K20me3 is essential for KDM4B’s rapid recruitment to DNA damage site, we further aligned the multiple tudor peptide sequence and identified two conserved residues Y993 and W987 that are critical for KDM4B-H4K20me3 interaction. The surface plasmon resonance analysis revealed that HTD displayed a rapid H4K20me3 bind-dissociate pattern. These findings therefore provided mechanistic insights into the binding of tudor domain of KDM4B protein with H4K20me3.

中文翻译：

---

组蛋白脱甲基酶KDM4B的Tudor结构域是H4K20me3的阅读器。

赖氨酸组蛋白脱甲基酶KDM4B在几种类型的癌症中过表达，并且在基因组稳定性维持中起双重作用。尽管KDM4B能够识别几种组蛋白甲基化，但是其潜在的分子机制仍然未知。在这项研究中，我们纯化了KDM4B染色质相关的杂交都铎结构域（HTD）和植物家乡域（PHD），并进行了拉下试验以筛选可以被KDM4B有效识别的三甲基修饰的组蛋白肽。我们的结果表明，单独的HTD以及HTD和PHD的组合都能够特异性结合H3K4me3和H4K20me3。由于H4K20me3对于KDM4B迅速募集到DNA损伤位点至关重要，我们进一步比对了多个都铎肽序列，并鉴定了两个保守残基Y993和W987，它们对于KDM4B-H4K20me3相互作用至关重要。表面等离子体共振分析表明，HTD显示出快速的H4K20me3结合-解离模式。因此，这些发现为了解KDM4B蛋白的Tudor结构域与H4K20me3的结合提供了机械原理。