INVIVO STUDIES ON THE DYNAMICS OF HISTONE DNA INTERACTION - EVIDENCE FOR NUCLEOSOME DISSOLUTION DURING REPLICATION AND TRANSCRIPTION AND A LOW-LEVEL OF DISSOLUTION INDEPENDENT OF BOTH
INVIVO STUDIES ON THE DYNAMICS OF HISTONE DNA INTERACTION - EVIDENCE FOR NUCLEOSOME DISSOLUTION DURING REPLICATION AND TRANSCRIPTION AND A LOW-LEVEL OF DISSOLUTION INDEPENDENT OF BOTH
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DOI：
10.1021/bi00455a019
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发表时间：
1990-01-23
期刊：
影响因子：
2.9
通讯作者：
JACKSON, V
中科院分区：
文献类型：
--
作者：
JACKSON, V
组蛋白在体内已用氨基酸进行放射性标记和密度标记，以确定在复制叉处以及在活性基因上组蛋白 - DNA和组蛋白 - 组蛋白相互作用的动态变化。蛋白质被均匀标记，随后追踪三个细胞世代。在追踪期间，H3、H4四聚体从H2A、H2B二聚体上解离，与追踪期间合成的相应非高密度组蛋白重新形成核小体。这些数据表明，在复制叉前进过程中，预复制核小体被溶解，相关组蛋白以H3、H4四聚体和H2A、H2B二聚体的形式释放。在放线菌素D存在的情况下对细胞进行密度标记的实验表明，先前描述的H2A、H2B的动态交换[Jackson, V. (1987) Biochemistry 26, 2315 - 2324]部分依赖于RNA聚合酶的移动。这些结果间接证明在转录过程中核小体溶解发生。当用阿糖胞苷和放线菌素D同时处理细胞抑制复制和转录过程中的沉积时，大多数新合成的组蛋白无法沉积到核小体结构中。观察到的低水平沉积具有与uH2A和uH2B沉积相似的特征，并且有人提出当这些蛋白质在细胞核内的游离池中时，H2A和H2B会被泛素结合。当新的H3、H4四聚体和新的H2A、H2B二聚体被阻止沉积时是不稳定的。新的和旧的H3和H4相互混合形成杂合四聚体，并且在H2A、H2B二聚体中也观察到类似的混合。提出了一个模型来描述在复制和转录过程中组蛋白 - DNA相互作用的动态变化。
Histones have been both radiolabeled and density-labeled with amino acids in vivo to determine the dynamics of histone-DNA and histone-histone interactions at the replication fork and on active genes. Proteins were uniformly labeled and subsequently chased for three cell generations. During the chase period, H3,H4 tetramers dissociated from the H2A,H2B dimers to re-form nucleosomes with the corresponding nondense histones synthesized during the chase period. These data suggest that the prereplicative nucleosomes are dissolved during advancement of the replication fork with release of associated histones in the form of the H3,H4 tetramers and H2A,H2B dimers. Experiments that involve density labeling of cells in the presence of actinomycin D indicate that the dynamic exchange of H2A,H2B that has been previously described [Jackson, V. (1987) Biochemistry 26, 2315-2324] is partially dependent on RNA polymerase movement. These results provide indirect evidence that nucleosome dissolution occurs during transcription. When deposition during replication and transcription is inhibited by simultaneous treatment of cells with cytosine arabinoside and actinomycin D, the majority of the newly synthesized histones are unable to deposit into nucleosome structure. The low level of deposition that is observed has characteristics similar to the deposition of uH2A and uH2B, and it is proposed that conjugation of H2A and H2B by ubiquitin occurs when these proteins are in a free pool within the nucleus. The new H3,H4 tetramers and new H2A,H2B dimers when prevented from depositing are not stable. New and old H3 and H4 intermix to form hybrid tetramers, and a similar intermixing is observed for the H2A,H2B dimers. A model is presented to describe the dynamics of histone-DNA interactions during replication and transcription.