Sequence and Nuclease Requirements for Breakage and Healing of a Structure-Forming (AT)n Sequence within Fragile Site FRA16D
Sequence and Nuclease Requirements for Breakage and Healing of a Structure-Forming (AT)n Sequence within Fragile Site FRA16D
复制标题
DOI：
10.1016/j.celrep.2019.03.103
复制
发表时间：
2019-04-23
期刊：
影响因子：
8.8
通讯作者：
Freudenreich, Catherine H.
中科院分区：
文献类型：
--
作者：
Kaushal, Simran;Wollmuth, Charles E.;Freudenreich, Catherine H.
常见的脆性部位(CFS)是人类中期染色体在复制压力下出现缺口和断裂的基因组区域，在癌细胞中经常被删除。我们研究了酵母中人CFS FRA16D的一个类似300bp的亚区(Flex1)，发现它概括了人类细胞中CFS脆性的特征。Flex1的脆性取决于可变长度的AT重复序列形成阻止复制的十字形结构的能力。Flex1的脆性是由结构特异性内切酶MUS81-MMS4与slx1-4/Rad1-10复合体共同作用启动的，而Yen1保护Flex1免受破坏。骨折后Flex1的愈合需要SAE2。我们的研究表明，CFS内的断裂可以由DNA结构上停滞的叉子上的核酸酶裂解开始。此外，我们的结果表明，CFS不仅容易破裂，而且其愈合能力也受到损害，这种有害的组合是它们脆弱的原因。
Common fragile sites (CFSs) are genomic regions that display gaps and breaks in human metaphase chromosomes under replication stress and are often deleted in cancer cells. We studied an similar to 300-bp subregion (Flex1) of human CFS FRA16D in yeast and found that it recapitulates characteristics of CFS fragility in human cells. Flex1 fragility is dependent on the ability of a variable-length AT repeat to form a cruciform structure that stalls replication. Fragility at Flex1 is initiated by structure-specific endonuclease Mus81-Mms4 acting together with the Slx1-4/Rad1-10 complex, whereas Yen1 protects Flex1 against breakage. Sae2 is required for healing of Flex1 after breakage. Our study shows that breakage within a CFS can be initiated by nuclease cleavage at forks stalled at DNA structures. Furthermore, our results suggest that CFSs are not just prone to breakage but also are impaired in their ability to heal, and this deleterious combination accounts for their fragility.