RecA Protein Recruits Structural Maintenance of Chromosomes (SMC)-like RecN Protein to DNA Double-strand Breaks |
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| Authors: | Kenji Keyamura Chikako Sakaguchi Yoshino Kubota Hironori Niki Takashi Hishida |
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| Institution: | From the ‡Department of Life Science, Graduate School of Science, Gakushuin University, Tokyo 171-8588.;the §Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, and ;the ¶Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan |
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| Abstract: | Escherichia coli RecN is an SMC (structural maintenance of chromosomes) family protein that is required for DNA double-strand break (DSB) repair. Previous studies show that GFP-RecN forms nucleoid-associated foci in response to DNA damage, but the mechanism by which RecN is recruited to the nucleoid is unknown. Here, we show that the assembly of GFP-RecN foci on the nucleoid in response to DNA damage involves a functional interaction between RecN and RecA. A novel RecA allele identified in this work, recAQ300R, is proficient in SOS induction and repair of UV-induced DNA damage, but is deficient in repair of mitomycin C (MMC)-induced DNA damage. Cells carrying recAQ300R fail to recruit RecN to DSBs and accumulate fragmented chromosomes after exposure to MMC. The ATPase-deficient RecNK35A binds and forms foci at MMC-induced DSBs, but is not released from the MMC-induced DNA lesions, resulting in a defect in homologous recombination-dependent DSB repair. These data suggest that RecN plays a crucial role in homologous recombination-dependent DSB repair and that it is required upstream of RecA-mediated strand exchange. |
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| Keywords: | ATPases DNA Damage DNA Damage Response DNA Recombination DNA Repair DNA-Protein Interaction DNA Double-strand Breaks |
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