Hassan Yousef I, Zempleni Janos
Department of Nutrition and Health Sciences, University of Nebraska at Lincoln, Lincoln, NE, USA.
J Nutr. 2006 Jul;136(7):1763-5. doi: 10.1093/jn/136.7.1763.
Covalent modifications of histones are a crucial component of epigenetic events that regulate chromatin structures and gene function. Evidence exists that distinct lysine residues in histones are modified by covalent attachment of the vitamin biotin, catalyzed by biotinidase and holocarboxylase synthetase. Biotinylation of histones appears to be conserved across species. The following biotinylation sites were identified using both MS and enzymatic biotinylation of synthetic peptides: K9, K13, K125, K127, and K129 in histone H2A; K4, K9, and K18 in histone H3; and K8 and K12 in histone H4. Evidence was provided that biotinylated histone H4 is enriched in pericentromeric heterochromatin, and that biotinylation of histone H4 participates in gene silencing, mitotic condensation of chromatin, and the cellular response to DNA damage. Biotinylation of histones is a reversible process and depends on the exogenous biotin supply, but the identities of histone debiotinylases remain uncertain. We propose that some effects of biotin deficiency can be attributed to abnormal chromatin structures.
组蛋白的共价修饰是调控染色质结构和基因功能的表观遗传事件的关键组成部分。有证据表明，组蛋白中不同的赖氨酸残基会被维生素生物素的共价连接修饰，该过程由生物素酶和全羧化酶合成酶催化。组蛋白的生物素化似乎在物种间保守。使用质谱法和合成肽的酶促生物素化鉴定出了以下生物素化位点：组蛋白H2A中的K9、K13、K125、K127和K129；组蛋白H3中的K4、K9和K18；以及组蛋白H4中的K8和K12。有证据表明，生物素化的组蛋白H4在着丝粒周围异染色质中富集，并且组蛋白H4的生物素化参与基因沉默、染色质的有丝分裂凝聚以及细胞对DNA损伤的反应。组蛋白的生物素化是一个可逆过程，取决于外源性生物素的供应，但组蛋白去生物素化酶的身份仍不确定。我们提出，生物素缺乏的一些影响可归因于异常的染色质结构。
