Homologous Recombination-dependent Rescue of Deficiency in the Structural Maintenance of Chromosomes (Smc) 5/6 Complex
Homologous Recombination-dependent Rescue of Deficiency in the Structural Maintenance of Chromosomes (Smc) 5/6 Complex
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DOI：
10.1074/jbc.m110.201608
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发表时间：
2011-02-18
影响因子：
4.8
通讯作者：
Johnson, F. Brad
中科院分区：
文献类型：
--
作者：
Chavez, Alejandro;Agrawal, Vishesh;Johnson, F. Brad
Smc 5-Smc 6复合体（Smc 5/6）是维持基因组稳定性的关键。Smc 5/6功能的部分丧失在DNA修复中产生几种缺陷，这些缺陷通过同源重组（HR）机制的失活而被挽救。因此，HR被认为对具有缺陷Smc 5/6的细胞具有毒性。最近的工作强调了Smc 5/6和Sgs 1 DNA解旋酶在防止未解决的HR中间体积累中的作用。在这里，我们调查如何删除MPH 1，编码人类FANCM DNA解旋酶的直向同源物，拯救smc 5/6，但不是sgs 1三角洲突变体的DNA损伤敏感性。我们发现，MPH 1缺失减少了smc 5/6和sgs 1 Delta细胞内HR中间体的积累，这表明MPH 1缺失足以减少模板转换重组（TSR）绕过DNA损伤的使用。我们进一步解释如何避免TSR仍然不足以拯救缺陷的sgs 1三角洲突变体，通过展示一个需要sgs 1，沿着的复制后修复（PRR）和HR机制，在一个途径，在mph 1三角洲突变体的运作。此外，我们映射的Mph 1的区域，结合Smc 5，并描述了一种新的等位基因的MPH 1编码的蛋白质不能结合Smc 5（mph 1-Delta 60）。值得注意的是，mph 1-Delta 60支持正常生长和对DNA损伤剂的反应，表明Smc 5/6并不简单地通过直接结合抑制Mph 1的重组活性。这些数据作为一个整体突出了Smc 5/6的作用，
The essential and evolutionarily conserved Smc5-Smc6 complex (Smc5/6) is critical for the maintenance of genome stability. Partial loss of Smc5/6 function yields several defects in DNA repair, which are rescued by inactivation of the homologous recombination (HR) machinery. Thus HR is thought to be toxic to cells with defective Smc5/6. Recent work has highlighted a role for Smc5/6 and the Sgs1 DNA helicase in preventing the accumulation of unresolved HR intermediates. Here we investigate how deletion of MPH1, encoding the orthologue of the human FANCM DNA helicase, rescues the DNA damage sensitivity of smc5/6 but not sgs1 Delta mutants. We find that MPH1 deletion diminishes accumulation of HR intermediates within both smc5/6 and sgs1 Delta cells, suggesting that MPH1 deletion is sufficient to decrease the use of template switch recombination (TSR) to bypass DNA lesions. We further explain how avoidance of TSR is nonetheless insufficient to rescue defects in sgs1 Delta mutants, by demonstrating a requirement for Sgs1, along with the post-replicative repair (PRR) and HR machinery, in a pathway that operates in mph1 Delta mutants. In addition, we map the region of Mph1 that binds Smc5, and describe a novel allele of MPH1 encoding a protein unable to bind Smc5 (mph1-Delta 60). Remarkably, mph1-Delta 60 supports normal growth and responses to DNA damaging agents, indicating that Smc5/6 does not simply restrain the recombinogenic activity of Mph1 via direct binding. These data as a whole highlight a role for Smc5/6 and