DEPOSITION-RELATED HISTONE ACETYLATION IN MICRONUCLEI OF CONJUGATING TETRAHYMENA
DEPOSITION-RELATED HISTONE ACETYLATION IN MICRONUCLEI OF CONJUGATING TETRAHYMENA
复制标题
DOI：
10.1073/pnas.82.23.8048
复制
发表时间：
1985-01-01
影响因子：
11.1
通讯作者：
SCHULMAN, IG
中科院分区：
文献类型：
--
作者：
ALLIS, CD;CHICOINE, LG;SCHULMAN, IG
纤毛原生动物，嗜热四膜虫的宏核和微核为研究组蛋白乙酰化提供了一个独特的机会，在这种条件下，乙酰化与组蛋白在DNA上的沉积是可分离的。在这项研究中，我们证明了在年轻的（5小时）偶联四膜虫中合成的组蛋白H3和组蛋白H4以乙酰化形式沉积到微核中。大多数新合成的组蛋白H3以单乙酰化形式迁移，而基本上所有新合成的组蛋白H4都以双乙酰化形式沉积。由于微核在生命周期的这一阶段复制迅速，但转录不活跃，这些数据表明组蛋白乙酰化在功能上与组蛋白沉积和染色质组装有关。脉冲追踪实验表明，微核还具有丁酸盐敏感脱乙酰酶活性（ies），该活性可以去除新合成和沉积的H3和H4中与沉积相关的乙酸基团。这种酶活性可能有助于微核组蛋白乙酰化的稳定水平低或不存在。因此，证据正在出现至少两个独立的系统组蛋白乙酰化在四膜虫。第一个系统是大核特异性的，可能与基因表达有关。第二种系统是宏观或微核组蛋白（H3和H4）所共有的，可能与DNA复制过程中的组蛋白沉积有关。
Macro- and micronuclei of the ciliated protozoan, Tetrahymena thermophila, afford a unique opportunity to study histone acetylation under conditions where acetylation associated with the deposition of histones on the DNA are separable. In this study we demonstrate that histone H3 and histone H4 synthesized in young (5 hr) conjugating Tetrahymena are deposited into micronuclei in acetylated forms. Most of the newly synthesized histone H3 migrates as a monoacetylated form while essentially all of the new histone H4 is deposited as a diacetylated species. Since micronuclei replicate rapidly during this stage of the life cycle, but are transcriptionally inactive, these data suggest that histone acetylation is related functionally to histone deposition and chromatin assembly. Pulse-chase experiments show that micronuclei also contain a butyrate-sensitive deacetylase activity(ies) which operates to remove the deposition-related acetate groups from newly synthesized and deposited H3 and H4. This enzymatic activity probably contributes to the steady state level of micronuclear histone acetylation that is low or nonexistent. Thus, evidence is emerging for at least two independent systems of histone acetylation in Tetrahymena. The first system is specific to macronuclei and may be related to gene expression. The second system is common to macro- or micronuclear histones (H3 and H4) and may be related to histone deposition during DNA replication.