Perry C A, Annunziato A T
Department of Biology, Boston College, Chestnut Hill, MA 02167.
Nucleic Acids Res. 1989 Jun 12;17(11):4275-91. doi: 10.1093/nar/17.11.4275.
In a previous report [Annunziato, A.T. and Seale, R.L. (1983) J. Biol. Chem. 258:12675] a novel intermediate in chromatin assembly was described (detected by labeling new DNA in the presence of the deacetylase inhibitor sodium butyrate), which retained approximately 50% of the heightened sensitivity of newly replicated chromatin to DNaseI. It is now reported that nucleosomes replicated in butyrate are considerably more soluble in the presence of magnesium, relative to chromatin replicated under control conditions, and that this heightened magnesium-solubility is reflected in a concomitant increase in the preferential solubility of nucleosomes containing newly synthesized core histones. This differential solubility was accompanied by a 5- to 6-fold depletion of histone H1, and was completely abolished by the selective removal of H1 from isolated nuclei. The removal of H1 also markedly reduced the preferential DNaseI sensitivity of chromatin replicated in butyrate. Further, when mononucleosomes of control and (acetylated) nascent chromatin were compared, no differences in DNaseI sensitivity were detected. These results provide evidence that the interactions between newly assembled nucleosomes and histone H1 are altered when histone deacetylation is inhibited during chromatin replication, and suggest a mechanism for the control of H1 deposition during nucleosome assembly in vivo.
在之前的一份报告中[安农齐亚托，A.T.和西尔，R.L.（1983年）《生物化学杂志》258:12675]，描述了一种染色质组装中的新型中间体（通过在脱乙酰酶抑制剂丁酸钠存在下标记新合成的DNA检测到），其保留了新复制染色质对DNaseI约50%的高敏感性。现在有报告称，相对于在对照条件下复制的染色质，在丁酸盐中复制的核小体在镁存在下的溶解性显著更高，并且这种增强的镁溶解性反映在含有新合成核心组蛋白的核小体优先溶解性的相应增加上。这种溶解性差异伴随着组蛋白H1减少5至6倍，并且通过从分离的细胞核中选择性去除H1而完全消除。去除H1也显著降低了在丁酸盐中复制的染色质对DNaseI的优先敏感性。此外，当比较对照染色质和（乙酰化的）新生染色质的单核小体时，未检测到DNaseI敏感性的差异。这些结果提供了证据，表明当染色质复制过程中组蛋白去乙酰化受到抑制时，新组装的核小体与组蛋白H1之间的相互作用会发生改变，并提示了一种体内核小体组装过程中H1沉积控制的机制。
