Nap1通过RAD51和RAD54在含有组蛋白H1的高阶染色质中刺激同源重组。
Nap1 stimulates homologous recombination by RAD51 and RAD54 in higher-ordered chromatin containing histone H1.
作者信息
Machida Shinichi, Takaku Motoki, Ikura Masae, Sun Jiying, Suzuki Hidekazu, Kobayashi Wataru, Kinomura Aiko, Osakabe Akihisa, Tachiwana Hiroaki, Horikoshi Yasunori, Fukuto Atsuhiko, Matsuda Ryo, Ura Kiyoe, Tashiro Satoshi, Ikura Tsuyoshi, Kurumizaka Hitoshi
机构信息
1] Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan [2].
Department of Mutagenesis, Division of Chromatin Regulatory Network, Radiation Biology Center, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan.
出版信息
Sci Rep. 2014 May 6;4:4863. doi: 10.1038/srep04863.
Homologous recombination plays essential roles in mitotic DNA double strand break (DSB) repair and meiotic genetic recombination. In eukaryotes, RAD51 promotes the central homologous-pairing step during homologous recombination, but is not sufficient to overcome the reaction barrier imposed by nucleosomes. RAD54, a member of the ATP-dependent nucleosome remodeling factor family, is required to promote the RAD51-mediated homologous pairing in nucleosomal DNA. In higher eukaryotes, most nucleosomes form higher-ordered chromatin containing the linker histone H1. However, the mechanism by which RAD51/RAD54-mediated homologous pairing occurs in higher-ordered chromatin has not been elucidated. In this study, we found that a histone chaperone, Nap1, accumulates on DSB sites in human cells, and DSB repair is substantially decreased in Nap1-knockdown cells. We determined that Nap1 binds to RAD54, enhances the RAD54-mediated nucleosome remodeling by evicting histone H1, and eventually stimulates the RAD51-mediated homologous pairing in higher-ordered chromatin containing histone H1.
同源重组在有丝分裂DNA双链断裂（DSB）修复和减数分裂基因重组中起着至关重要的作用。在真核生物中，RAD51在同源重组过程中促进核心同源配对步骤，但不足以克服核小体所施加的反应障碍。RAD54是ATP依赖性核小体重塑因子家族的成员，是促进核小体DNA中RAD51介导的同源配对所必需的。在高等真核生物中，大多数核小体形成包含连接组蛋白H1的高阶染色质。然而，RAD51/RAD54介导的同源配对在高阶染色质中发生的机制尚未阐明。在本研究中，我们发现一种组蛋白伴侣Nap1在人类细胞的DSB位点上积累，并且在Nap1敲低的细胞中DSB修复显著降低。我们确定Nap1与RAD54结合，通过驱逐组蛋白H1增强RAD54介导的核小体重塑，并最终刺激在含有组蛋白H1的高阶染色质中RAD51介导的同源配对。
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