Nonrandom assembly of chromatin during hydroxyurea inhibition of DNA synthesis.
Nonrandom assembly of chromatin during hydroxyurea inhibition of DNA synthesis.
复制标题
羟基脲抑制 DNA 合成过程中染色质的非随机组装。
DOI：
10.1021/bi00402a029
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Leffak,M
中科院分区：
文献类型：
--
作者：
Leffak,M
赖特州立大学生物化学系，俄亥俄州代顿45435摘要：用羟基脲孵育MSB-1鸡淋巴母细胞样细胞，导致[3H]胸腺嘧啶进入DNA的数量迅速减少25倍，[3H]赖氨酸进入核小体核心组蛋白的数量减少5倍。我已经研究了组蛋白dna合成正常比例的扭曲是否会导致核小体组装过程的改变，并发现在羟基脲孵育期间，新组蛋白合成的化学计量学和沉积都没有明显改变。蛋白质交联和微球菌核酸酶切表明，羟基脲处理过程中合成的组蛋白形成八聚体结构，并组装成典型的核小体颗粒。发现小核小体亚群对核酸酶消化的敏感性改变，并且在新的组蛋白H3和H4中被耗尽。当在羟基脲中培养的MSB-1细胞被密度标记的氨基酸和[3H]赖氨酸短暂脉冲时，形成的放射性标记的核心组蛋白八聚体与单个单体组蛋白一样致密。这些结果表明，新合成的组蛋白八聚体密度均匀，不含有新旧组蛋白的混合物。因此，在羟基脲孵育过程中合成的组蛋白是非随机沉积的，不与先前存在的组蛋白交换。染色质在体内的组装反映了几个调控过程的相互作用，包括组蛋白和DNA在S期的协调合成和DNA的合成
Department of Biochemistry, Wright State University, Dayton, Ohio 45435 Received August 19, 1987; Revised Manuscript Received October 8, 1987 abstract: Incubation of MSB-1 chicken lymphoblastoid cells with hydroxyurea leads to a rapid 25-fold decrease in the incorporation of [3H] thymidine into DNA and a 5-fold decrease of [3H] lysine into the nucleosome core histones. I have investigatedwhether the distortion in the normal proportion of histone-DNA synthesis results in alterations in the nucleosome assembly process and find that neither the stoichiometry of new histone synthesis nor the deposition is appreciably changed during hydroxyurea incubation. Protein cross-linking and micrococcal nuclease digestion show that the histones synthesized during hydroxyurea treatment form octamer structures and are assembled into typical nucleosome particles. Minor nucleosome subpopulations are found which exhibit altered sensitivity to nuclease digestion and which are depleted in new histones H3 and H4. When MSB-1 cells incubated in hydroxyurea are pulsed briefly with density-labeled amino acids and [3H] lysine, the radiolabeled core histone octamers formed are as dense as individual monomer histones. These results suggest that the newly synthesized histone octamers are uniformly dense and do not contain mixtures of new and old histones. Thus, histones synthesized during hydroxyurea incubation are deposited nonrandomly and do not exchange with preexistinghistones. e assembly of chromatinin vivo reflects the interplay of several regulated processes, including the coordinated synthesis of histones and DNA during S phase and the synthesis of