Identification and characterization of human MUS81-MMS4 structure-specific endonuclease
Identification and characterization of human MUS81-MMS4 structure-specific endonuclease
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DOI：
10.1074/jbc.m302484200
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发表时间：
2003-06-13
影响因子：
4.8
通讯作者：
Sancar, A
中科院分区：
文献类型：
--
作者：
Ögrünç, M;Sancar, A
当复制叉到达DNA模板上的一个块（例如DNA损伤）时，它们可能会停止，并且这种停止的复制叉的恢复在维持基因组稳定性方面起着至关重要的作用。霍利迪连接是X形DNA结构，在停滞的复制叉处形成，并且如果它们不被结构特异性核酸内切酶切割，则可以积累。最近，在酵母和人类中报道了一种新的参与解析霍利迪连接样结构的核酸酶Mus81。MUS81与另一种DNA核酸酶XPF具有序列同源性，XPF与其伴侣ERCC1在核苷酸切除修复期间进行5 '切口。MUS81在酿酒酵母中也有一个名为Mms4的结合伴侣，在粟酒裂殖酵母中也有一个名为Eme1的结合伴侣，但在人类细胞中没有发现这样的伴侣。在这里，我们报告了人MUS81的结合伴侣的鉴定，我们将其命名为hMMS 4。使用免疫亲和纯化，我们表明，hMUS81或hMMS 4单独没有可检测的核酸酶活性，但hMUS81。hMMS4复合物是一种结构特异性核酸酶，能够解析叉结构。
Replication forks may stall when they reach a block on the DNA template such as DNA damage, and the recovery of such stalled replication forks plays a crucial role in the maintenance of genomic stability. Holliday junctions, which are X- shaped DNA structures, are formed at the stalled replication forks and can accumulate if they are not cleaved by structure- specific endonucleases. Recently, a novel nuclease involved in resolving Holliday junction- like structures, Mus81, has been reported in yeast and humans. MUS81 has sequence homology to another DNA nuclease, XPF, which, with its partner ERCC1, makes the 5 ' incision during nucleotide excision repair. MUS81 also has a binding partner named Mms4 in Saccharomyces cerevisiae and Eme1 in Schizosaccharomyces pombe, but no such partner was identified in human cells. Here, we report identification of the binding partner of human MUS81, which we designate hMMS4. Using immunoaffinity purification we show that hMUS81 or hMMS4 alone have no detectable nuclease activity, but that the hMUS81 . hMMS4 complex is a structure- specific nuclease that is capable of resolving fork structures.