Life Science College, Beijing Normal University, Beijing 100875, China.
EMBO Rep. 2011 Mar;12(3):244-51. doi: 10.1038/embor.2011.6. Epub 2011 Feb 18.
Two copies of each core histone exist in every nucleosome; however, it is not known whether both histones within a nucleosome are required to be symmetrically methylated at the same lysine residues. We report that for most lysine methylation states, wild-type histones paired with mutant, unmethylatable histones in mononucleosomes have comparable methylation levels to bulk histones. Our results indicate that symmetrical histone methylation is not required on a global scale. However, wild-type H4 histones paired with unmethylatable H4K20R histones showed reduced levels of H4K20me2 and H4K20me3, suggesting that some fractions of these modifications might exist symmetrically, and enzymes mediating these modifications might, to some extent, favour nucleosome substrates with premethylated H4K20.
每个核小体中存在两份每种核心组蛋白；然而，尚不清楚核小体中的两个组蛋白是否都需要在相同的赖氨酸残基上对称地甲基化。我们报告说，对于大多数赖氨酸甲基化状态，在单核小体中，野生型组蛋白与突变的、不可甲基化的组蛋白配对具有与整体组蛋白相当的甲基化水平。我们的结果表明，全局范围内不需要对称的组蛋白甲基化。然而，野生型 H4 组蛋白与不可甲基化的 H4K20R 组蛋白配对显示出 H4K20me2 和 H4K20me3 的水平降低，这表明这些修饰的某些部分可能是对称存在的，并且介导这些修饰的酶可能在某种程度上偏爱具有预甲基化 H4K20 的核小体底物。
