Fission yeast Ku protein is required for recovery from DNA replication stress
Fission yeast Ku protein is required for recovery from DNA replication stress
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DOI：
10.1111/j.1365-2443.2009.01337.x
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发表时间：
2009-09
期刊：
影响因子：
2.1
通讯作者：
Tomoichiro Miyoshi;J. Kanoh;F. Ishikawa
中科院分区：
文献类型：
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作者：
Tomoichiro Miyoshi;J. Kanoh;F. Ishikawa
保守的Ku70-Ku80异源二聚体的基本功能是促进双链断裂修复中的非同源末端连接（NHEJ）途径。尽管人们认为Ku在维持染色体完整性包括端粒保护方面除了NHEJ外还发挥着其他作用，但这些确切的功能尚不清楚。在这项研究中，我们描述了由pku70+和pku80+基因编码的裂变酵母Ku蛋白在处理DNA复制胁迫中的新作用。在缺少Rqh1，即裂变酵母req解旋酶的情况下，细胞对诱导复制应激的试剂敏感。PkuΔrqh1Δ双突变体对这些试剂表现出协同敏感性。然而，当rqh1Δ突变体与编码NHEJ必需连接酶的lig4+缺失偶联时，没有观察到这种合成表型，这表明Ku在复制胁迫中的作用与NHEJ无关。pkuΔrqh1Δ双突变体即使在非胁迫条件下也表现出高度可变的rDNA重复拷贝数。此外，双突变体在短暂复制停滞后表现出低效率的复制恢复。这些结果表明，Ku蛋白可能在基因组完整性恢复复制胁迫中发挥重要作用。
The fundamental function of the conserved Ku70–Ku80 heterodimer is to promote the non‐homologous end‐joining (NHEJ) pathway in double‐strand break repair. Although it is thought that Ku plays several roles other than NHEJ in maintaining chromosomal integrity including telomere protection, these precise functions remain unclear. In this study, we describe a novel role of fission yeast Ku proteins encoded by pku70+ and pku80+ genes in dealing with DNA replication stress. In the absence of Rqh1, the fission yeast RecQ helicase, the cells are sensitive to reagents inducing replication stress. pkuΔrqh1Δ double mutant showed synergistic sensitivities to these reagents. However, this synthetic phenotype was not observed when rqh1Δ mutant was coupled with the deletion of lig4+ that encodes a ligase essential for NHEJ, indicating that the role of Ku in replication stress is NHEJ independent. pkuΔrqh1Δ double mutant also showed highly variable copy numbers of rDNA repeats even under unstressed condition. Furthermore, the double mutant exhibited inefficient replication resumption after transient replication stalling. These results suggest the possibility that Ku proteins play an important role in genome integrity recovering replication stress.