Identification of a Saccharomyces cerevisiae Ku80 homologue: Roles in DNA double strand break rejoining and in telomeric maintenance
Identification of a Saccharomyces cerevisiae Ku80 homologue: Roles in DNA double strand break rejoining and in telomeric maintenance
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DOI：
10.1093/nar/24.23.4639
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发表时间：
1996-12-01
影响因子：
14.9
通讯作者：
Jackson, SP
中科院分区：
文献类型：
--
作者：
Boulton, SJ;Jackson, SP
Ku是一种结合在DNA末端的约70和80 kDa的多肽异二聚体（分别为Ku70和Ku80），缺乏Ku的哺乳动物细胞在DNA双链断裂（DSB）修复和位点特异性V(D)J重组中存在缺陷。在这里，我们描述了YKU80的鉴定和特征，这是酵母Ku80同源基因，值得注意的是，我们发现YKU80的破坏增强了rad52突变菌株的辐射敏感性。这表明YKU80在DNA DSB修复途径中起作用，而不依赖于同源重组。事实上，通过使用体内质粒重新连接实验，我们发现YKU80在非法重组事件中起重要作用，导致限制性内切酶产生的DSB的准确修复。有趣的是，在没有YKU80功能的情况下，残留修复通过容易出错的途径进行，导致短直接重复元件之间的重组。总之，我们的数据表明，真核生物中存在多种进化上保守的DSB修复机制，此外，它们表明Ku在体内与DSB结合，并通过增强准确的DNA末端连接和抑制其他容易出错的修复途径来促进修复。最后，我们报道yku80突变酵母显示出显着的端粒缩短，这表明，除了识别DNA损伤外，Ku还结合到自然发生的染色体末端，这些发现提出了Ku保护染色体末端免受ii核溶解攻击的可能性，并作为端粒长度传感系统的一部分发挥作用。
Ku is a heterodimer of polypeptides of approximately 70 and 80 kDa (Ku70 and Ku80, respectively) that binds to DNA ends, Mammalian cells lacking Ku are defective in DNA double-strand break (DSB) repair and in site-specific V(D)J recombination, Here, we describe the identification and characterisation of YKU80,the gene for the Saccharomyces cerevisiae Ku80 homologue, Significantly, we find that YKU80 disruption enhances the radiosensitivity of rad52 mutant strains, suggesting that YKU80 functions in a DNA DSB repair pathway that does not rely on homologous recombination, Indeed, through using an in vivo plasmid rejoining assay, we find that YKU80 plays an essential role in illegitimate recombination events that result in the accurate repair of restriction enzyme generated DSBs, Interestingly, in the absence of YKU80 function, residual repair operates through an error-prone pathway that results in recombination between short direct repeat elements. This resembles closely a predominant DSB repair pathway in vertebrates, Together, our data suggest that multiple, evolutionarily conserved mechanisms for DSB repair exist in eukaryotes, Furthermore, they imply that Ku binds to DSBs in vivo and promotes repair both by enhancing accurate DNA end joining and by suppressing alternative error-prone repair pathways, Finally, we report that yku80 mutant yeasts display dramatic telomeric shortening, suggesting that, in addition to recognising DNA damage, Ku also binds to naturally occurring chromosomal ends, These findings raise the possibility that Ku protects chromosomal termini from ii nucleolytic attack and functions as part of a telomeric length sensing system.