To determine whether double-strand break (DSB) mobility enhances the physical search for an ectopic template during homology-directed repair (HDR), we tested the effects of factors that control chromatin dynamics, including cohesin loading and kinetochore anchoring. The former but not the latter is altered in response to DSBs. Loss of the nonhistone high-mobility group protein Nhp6 reduces histone occupancy and increases chromatin movement, decompaction, and ectopic HDR. The loss of nucleosome remodeler INO80-C did the opposite. To see whether enhanced HDR depends on DSB mobility or the global chromatin response, we tested the ubiquitin ligase mutant uls1Δ, which selectively impairs local but not global movement in response to a DSB. Strand invasion occurs in uls1Δ cells with wild-type kinetics, arguing that global histone depletion rather than DSB movement is rate limiting for HDR. Impaired break movement in uls1Δ correlates with elevated MRX and cohesin loading, despite normal resection and checkpoint activation.

为了确定双链断裂（DSB）流动性是否在同源性定向修复（HDR）期间增强了对异位模板的物理搜索，我们测试了控制染色质动力学的因素的影响，包括黏着素加载和动粒锚定。前者（而不是后者）会根据DSB进行更改。非组蛋白高迁移率族蛋白Nhp6的丢失会降低组蛋白的占有率，并增加染色质的移动，分解和异位HDR。核小体重塑剂INO80-C的丧失则相反。为了查看增强的HDR是否依赖于DSB流动性或全局染色质响应，我们测试了泛素连接酶突变体uls1Δ，该突变体选择性地损害了响应DSB的局部而不是全局运动。链入侵发生在uls1Δ中具有野生型动力学的细胞，认为整体组蛋白耗竭而不是DSB运动是HDR的速率限制。尽管正常切除和检查点激活，但uls1Δ的断裂运动受损与MRX和黏附素负荷增加有关。