ABSTRACT Constitutive heterochromatin is considered as a functionally inert genome compartment, important for its architecture and stability. How such stable structure is maintained is not well understood. Here, we apply four different visualization schemes to label it and investigate its dynamics during DNA replication and repair. We show that replisomes assemble over the heterochromatin in a temporally ordered manner. Furthermore, heterochromatin undergoes transient decompaction locally at the active sites of DNA synthesis. Using selective laser microirradiation conditions that lead to damage repaired via processive DNA synthesis, we measured similarly local decompaction of heterochromatin. In both cases, we could not observe large-scale movement of heterochromatin to the domain surface. Instead, the processive DNA synthesis machinery assembled at the replication/repair sites. Altogether, our data are compatible with a progression of DNA replication/repair along the chromatin in a dynamic mode with localized and transient decompaction that does not globally remodels the whole heterochromatin compartment.

中文翻译：

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持续性 DNA 合成与 DNA 复制和修复位点的组成型异染色质局部解压缩有关


摘要 组成型异染色质被认为是功能惰性的基因组区室，对其结构和稳定性很重要。如何维持这种稳定的结构尚不清楚。在这里，我们应用四种不同的可视化方案来标记它并研究它在 DNA 复制和修复过程中的动态。我们证明复制体以时间顺序的方式在异染色质上组装。此外，异染色质在 DNA 合成的活性位点局部经历短暂的解压缩。使用选择性激光微照射条件，通过持续 DNA 合成修复损伤，我们测量了类似的异染色质局部解压。在这两种情况下，我们都无法观察到异染色质向结构域表面的大规模移动。相反，持续的 DNA 合成机器在复制/修复位点组装。总而言之，我们的数据与动态模式下沿染色质的 DNA 复制/修复进展相一致，具有局部和瞬时解压，不会全局重塑整个异染色质区室。