Marseille Cancer Research Centre (CRCM), U1068 INSERM, UMR7258 CNRS, UM105 Aix-Marseille University, Institute Paoli-Calmettes, Ligue Nationale Contre le Cancer (Equipe Labellisée), Marseille, France.
IFOM ETS - the AIRC Institute of Molecular Oncology, Milan, Italy.
Nat Commun. 2023 Sep 5;14(1):5430. doi: 10.1038/s41467-023-41100-4.
Homologous recombination factors play a crucial role in protecting nascent DNA during DNA replication, but the role of chromatin in this process is largely unknown. Here, we used the bacterial Tus/Ter barrier known to induce a site-specific replication fork stalling in S. cerevisiae. We report that the Set1C subunit Spp1 is recruited behind the stalled replication fork independently of its interaction with Set1. Spp1 chromatin recruitment depends on the interaction of its PHD domain with H3K4me3 parental histones deposited behind the stalled fork. Its recruitment prevents the accumulation of ssDNA at the stalled fork by restricting the access of Exo1. We further show that deleting SPP1 increases the mutation rate upstream of the barrier favoring the accumulation of microdeletions. Finally, we report that Spp1 protects nascent DNA at the Tus/Ter stalled replication fork. We propose that Spp1 limits the remodeling of the fork, which ultimately limits nascent DNA availability to nucleases.
同源重组因子在保护 DNA 复制过程中的新生 DNA 方面发挥着至关重要的作用，但染色质在这个过程中的作用在很大程度上是未知的。在这里，我们使用了已知能够在酿酒酵母中诱导特定复制叉停滞的细菌 Tus/Ter 屏障。我们报告说，Set1C 亚基 Spp1 被招募到停滞的复制叉后面，而不依赖于它与 Set1 的相互作用。Spp1 染色质的募集依赖于其 PHD 结构域与停滞叉后面沉积的 H3K4me3 亲本组蛋白的相互作用。它的募集通过限制 Exo1 的进入来防止在停滞叉处积累单链 DNA。我们进一步表明，删除 SPP1 会增加屏障上游的突变率，有利于微缺失的积累。最后，我们报告说 Spp1 可以保护 Tus/Ter 停滞复制叉处的新生 DNA。我们提出，Spp1 限制了叉的重塑，这最终限制了新生 DNA 对核酸酶的可利用性。
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