Purification and functional characterization of SET8, a nucleosomal histone H4-lysine 20-specific methyltransferase
Purification and functional characterization of SET8, a nucleosomal histone H4-lysine 20-specific methyltransferase
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DOI：
10.1016/s0960-9822(02)00924-7
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发表时间：
2002-07-09
期刊：
影响因子：
9.2
通讯作者：
Zhang, Y
中科院分区：
文献类型：
--
作者：
Fang, J;Feng, Q;Zhang, Y
背景：组蛋白n端尾部共价修饰在调节染色质结构和功能中起着重要作用。大量研究表明，组蛋白尾部特定赖氨酸残基的乙酰化在转录调控中起着重要作用。除了乙酰化，最近的研究表明组蛋白甲基化对异染色质的形成和转录调控也有重要影响。组蛋白甲基化发生在组蛋白H3和H4的特定精氨酸和赖氨酸残基上。到目前为止，组蛋白H4上只有2个残基被甲基化。虽然h4 -精氨酸3 （H4-R3）甲基化是由PRMT1介导的，但负责h4 -赖氨酸20 （H4-K20）甲基化的酶是未知的。结果：为了深入了解H4-K20甲基化的功能，我们开始确定负责这种修饰的酶。我们纯化并克隆了一种新的人类SET结构域蛋白，命名为SET8，它特异性地甲基化了K20处的H4。SET8是一种单亚基酶，倾向于核小体底物。我们发现H4-K20甲基化发生在广泛的高等真核生物中，SET8同源物存在于秀丽隐杆线虫和果蝇中。我们证明果蝇SET8同源物与人类同源物具有相同的底物特异性。重要的是，果蝇体内SET8的破坏会降低体内H4-K20甲基化水平并导致死亡。虽然H4-K20甲基化与基因活性无关，但它似乎在细胞周期中受到调节。结论：我们鉴定并鉴定了一种进化上保守的核小体h4 - k20特异性甲基转移酶，并证明了其在果蝇发育中的重要作用。
Background: Covalent modifications of histone N-terminal tails play fundamental roles in regulating chromatin structure and function. Extensive studies have established that acetylation of specific lysine residues in the histone tails plays an important role in transcriptional regulation. Besides acetylation, recent studies have revealed that histone methylation also has significant effects on heterochromatin formation and transcriptional regulation. Histone methylation occurs on specific arginine and lysine residues of histones H3 and H4. Thus far, only 2 residues on histone H4 are known to be methylated. While H4-arginine 3 (H4-R3) methylation is mediated by PRMT1, the enzyme(s) responsible for H4-lysine 20 (H4-K20) methylation is not known.Results: To gain insight into the function of H4-K20 methylation, we set out to identify the enzyme responsible for this modification. We purified and cloned a novel human SET domain-containing protein, named SET8, which specifically methylates H4 at K20. SET8 is a single subunit enzyme and prefers nucleosomal substrates. We find that H4-K20 methylation occurs in a wide range of higher eukaryotic organisms and that SET8 homologs exist in C. elegans and Drosophila. We demonstrate that the Drosophila SET8 homolog has the same substrate specificity as its human counterpart. Importantly, disruption of SET8 in Drosophila reduces levels of H4-K20 methylation in vivo and results in lethality. Although H4-K20 methylation does not correlate with gene activity, it appears to be regulated during the cell cycle.Conclusions: We identified and characterized an evolutionarily conserved nucleosomal H4-K20-specific methyltransferase and demonstrated its essential role in Drosophila development.