Human RAD52 Captures and Holds DNA Strands, Increases DNA Flexibility, and Prevents Melting of Duplex DNA: Implications for DNA Recombination
Human RAD52 Captures and Holds DNA Strands, Increases DNA Flexibility, and Prevents Melting of Duplex DNA: Implications for DNA Recombination
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DOI：
10.1016/j.celrep.2017.02.068
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发表时间：
2017-03-21
期刊：
影响因子：
8.8
通讯作者：
Modesti, Mauro
中科院分区：
文献类型：
--
作者：
Brouwer, Ineke;Zhang, Hongshan;Modesti, Mauro
人类 RAD52 促进互补单链 DNA (ssDNA) 的退火。需要深入了解 RAD52-DNA 相互作用才能了解其活性如何整合到 DNA 修复过程中。在这里，我们可视化了与单个 DNA 分子相互作用的单个荧光 RAD52 复合物。与 ssDNA 的相互作用是快速、静态和紧密的，其中 ssDNA 似乎包裹着促进分子内桥接的 RAD52 复合物。对于双链 DNA (dsDNA)，相互作用更慢、更弱，并且通常是扩散的。有趣的是，力谱实验表明，RAD52 通过增强 DNA 柔韧性和增加 DNA 轮廓长度来改变双链 DNA 的力学结构，这表明存在嵌入现象。 RAD52 结合改变了 dsDNA 过度拉伸转变的性质并防止 DNA 熔化，这有利于退火期间或退火后的链夹紧。 DNA 结合的 RAD52 能够有效捕获反式 ssDNA。总之，这些效应可能有助于 DNA 修复的关键步骤，例如同源重组期间的第二端捕获或不依赖于 RAD51 的重组反应期间的链退火。
Human RAD52 promotes annealing of complementary single-stranded DNA (ssDNA). In-depth knowledge of RAD52-DNA interaction is required to understand how its activity is integrated in DNA repair processes. Here, we visualize individual fluorescent RAD52 complexes interacting with single DNA molecules. The interaction with ssDNA is rapid, static, and tight, where ssDNA appears to wrap around RAD52 complexes that promote intra-molecular bridging. With double-stranded DNA (dsDNA), interaction is slower, weaker, and often diffusive. Interestingly, force spectroscopy experiments show that RAD52 alters the mechanics dsDNA by enhancing DNA flexibility and increasing DNA contour length, suggesting intercalation. RAD52 binding changes the nature of the overstretching transition of dsDNA and prevents DNA melting, which is advantageous for strand clamping during or after annealing. DNA-bound RAD52 is efficient at capturing ssDNA in trans. Together, these effects may help key steps in DNA repair, such as second-end capture during homologous recombination or strand annealing during RAD51-independent recombination reactions.