Strand exchange activity of human recombination protein Rad52
Strand exchange activity of human recombination protein Rad52
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DOI：
10.1073/pnas.0403416101
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发表时间：
2004-06-29
影响因子：
11.1
通讯作者：
Gupta, RC
中科院分区：
文献类型：
--
作者：
Kumar, JK;Gupta, RC
双链断裂的修复对于维持基因组完整性和细胞存活至关重要。在真核生物中，通过同源重组进行的双链断裂修复需要Rad52组蛋白。人Rad52蛋白（HsRad52）介导的互补链退火已被详细研究，但很少有关于HsRad52的重组酶活性的报道。在这项研究中，我们纯化HsRad52从大肠杆菌。DNA酶I保护实验表明HsRad52优先结合单链DNA并保护其免受DNA酶I的消化。HsRad52催化超螺旋DNA中D环的形成，以及寡核苷酸底物之间的链交换。HsRad52和单链DNA之间的化学计量复合物的形成被认为是链交换活性的关键，并且单链和双链寡核苷酸的涂层抑制了交换反应。
Repair of double-strand breaks is essential for the maintenance of genome integrity and cell survival. In eukaryotes, double-strand-break repair by homologous recombination requires the Rad52 group of proteins. Human Rad52 protein (HsRad52)-mediated annealing of complementary strands has been studied in detail, but little has been reported on the recombinase activities of HsRad52. For this study, we purified HsRad52 from Escherichia coli. DNase I protection experiments indicated that HsRad52 binds preferentially to single-stranded DNA and protects it against digestion by DNase I. HsRad52 catalyzed D-loop formation in superhelical DNA, as well as strand exchange among oligonucleotide substrates. The formation of a stoichiometric complex between HsRad52 and single-stranded DNA was found to be critical for strand exchange activity, and the coating of both the single- and double-stranded oligonucleotides inhibited the exchange reaction.