Endonucleolytic processing of covalent protein-linked DNA double-strand breaks
Endonucleolytic processing of covalent protein-linked DNA double-strand breaks
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DOI：
10.1038/nature03872
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发表时间：
2005-08-18
期刊：
影响因子：
64.8
通讯作者：
Keeney, S
中科院分区：
文献类型：
--
作者：
Neale, MJ;Pan, J;Keeney, S
Spo11通过DNA双链断裂(DSB)启动减数分裂重组(1，2)。必须去除Spo11蛋白才能修复DSB，但去除机制尚不清楚(3)。在这里，我们展示了芽期酵母中减数分裂的DSB是通过内切切割来处理的，它释放连接到带有游离3‘-OH的寡核苷酸上的Spo11。发现两个离散的Spo11-寡核苷酸复合体，数量相等，但结合DNA的长度不同。我们认为，这些形式是由DSB两侧不同间距的链切割引起的，每个DSB都是不对称处理的。因此，单个DSB的末端在初始处理步骤或之前可能在生化上是不同的--比之前认为的要早得多。在小鼠睾丸提取液中发现了SPO11-寡核苷酸复合体，这表明这种机制在进化上是保守的。营养酵母的提取物中也存在寡核苷酸-拓扑异构酶II复合体，尽管不受产生Spo11-寡核苷酸复合体的相同遗传控制。我们的发现提示了蛋白质相关双链断裂修复的一般机制。
DNA double-strand breaks (DSBs) with protein covalently attached to 50 strand termini are formed by Spo11 to initiate meiotic recombination(1,2). The Spo11 protein must be removed for the DSB to be repaired, but the mechanism for removal is unclear(3). Here we show that meiotic DSBs in budding yeast are processed by endonucleolytic cleavage that releases Spo11 attached to an oligonucleotide with a free 3'-OH. Two discrete Spo11-oligonucleotide complexes were found in equal amounts, differing with respect to the length of the bound DNA. We propose that these forms arise from different spacings of strand cleavages flanking the DSB, with every DSB processed asymmetrically. Thus, the ends of a single DSB may be biochemically distinct at or before the initial processing step - much earlier than previously thought. SPO11- oligonucleotide complexes were identified in extracts of mouse testis, indicating that this mechanism is evolutionarily conserved. Oligonucleotide - topoisomerase II complexes were also present in extracts of vegetative yeast, although not subject to the same genetic control as for generating Spo11 - oligonucleotide complexes. Our findings suggest a general mechanism for repair of protein-linked DSBs.