Institute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou, China.
DNA Repair (Amst). 2010 Jul 1;9(7):805-12. doi: 10.1016/j.dnarep.2010.04.006. Epub 2010 May 6.
The bacterium Deinococcus radiodurans can survive extremely high exposure to ionizing radiation. The repair mechanisms involved in this extraordinary ability are still being investigated. ddrB is one gene that is highly up-regulated after irradiation, and it has been proposed to be involved in RecA-independent repair in D. radiodurans. Here we cloned, expressed and characterized ddrB in order to define its roles in the radioresistance of D. radiodurans. DdrB preferentially binds to single-stranded DNA. Moreover, it interacts directly with single-stranded binding protein of D. radiodurans DrSSB, and stimulates single-stranded DNA annealing even in the presence of DrSSB. The post-irradiation DNA repair kinetics of a ddrB/recA double mutant were compared to ddrB and recA single mutants by pulsed-field gel electrophoresis (PFGE). DNA fragment rejoining in the ddrB/recA double mutant is severely compromised, suggesting that DdrB-mediated single-stranded annealing plays a critical role in the RecA-independent DNA repair of D. radiodurans.
耐辐射球菌可以在极高剂量的电离辐射下存活。目前仍在研究其具有这种非凡能力所涉及的修复机制。ddrB 是一种在照射后高度上调的基因，它被提议参与耐辐射球菌的 RecA 非依赖性修复。在这里，我们克隆、表达和表征了 ddrB，以确定其在耐辐射球菌的辐射抗性中的作用。DdrB 优先与单链 DNA 结合。此外，它与耐辐射球菌 DrSSB 的单链结合蛋白直接相互作用，并在存在 DrSSB 的情况下刺激单链 DNA 退火。通过脉冲场凝胶电泳（PFGE）比较了 ddrB/recA 双突变体与 ddrB 和 recA 单突变体的辐射后 DNA 修复动力学。ddrB/recA 双突变体中的 DNA 片段重新连接严重受损，表明 DdrB 介导的单链退火在耐辐射球菌的 RecA 非依赖性 DNA 修复中起着关键作用。
