Histone H3 leads a double life as a copper reductase Histone proteins are the ubiquitous organizers of all eukaryotic genomes (1). Two each of the histones H2A, H2B, H3, and H4 form a disk-shaped assembly around which 147 base pairs (bp) of DNA are tightly coiled. Hundreds of thousands of these connected nucleosomes wrap up further to form chromosomes. The substantial sequence conservation between eukaryotic histones and the presence of simple histones in archaea (the presumed ancestors of all eukaryotes) suggest an ancient evolutionary origin of this type of genome organization (2). Certainly, there was no reason to believe that histones had any other function, let alone enzymatic activity. On page 59 of this issue, Attar et al. (3) describe the unexpected discovery that histone H3 has copper reductase activity in yeast (and likely in all) cells, suggesting that histones may have evolved to adapt to oxygenated life rather than for DNA compaction.

中文翻译：

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组蛋白的秘密生活

组蛋白 H3 作为铜还原酶具有双重生命 组蛋白是所有真核生物基因组中无处不在的组织者 (1)。组蛋白 H2A、H2B、H3 和 H4 中的每两个形成一个盘状组件，147 个 DNA 碱基对 (bp) 围绕该组件紧密盘绕。成千上万的这些相互连接的核小体进一步包裹起来形成染色体。真核生物组蛋白之间的大量序列保守性和古细菌（所有真核生物的假定祖先）中简单组蛋白的存在表明这种基因组组织的古老进化起源 (2)。当然，没有理由相信组蛋白有任何其他功能，更不用说酶活性了。在本期第 59 页上，Attar 等人。(3) 描述组蛋白 H3 在酵母（可能在所有）细胞中具有铜还原酶活性的意外发现，