Rtt105 functions as a chaperone for replication protein A to preserve genome stability |
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| Authors: | Linyu Zuo Chuanhe Yu Pu Zheng Haiyun Gan Xuezheng Wang Longtu Li Sushma Sharma Andrei Chabes Di Li Sheng Wang Sihao Zheng Jinbao Li Xuefeng Chen Yujie Sun Dongyi Xu Junhong Han Kuiming Chan Zhi Qi Jianxun Feng Qing Li |
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| Institution: | 1. Peking‐Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China;2. Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China;3. Department of Pediatrics and Department of Genetics and Development, Institute for Cancer Genetics, Columbia University, College of Physicians and Surgeons, New York, NY, USA;4. State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China;5. Medical Biochemistry and Biophysics, Ume? University, Ume?, Sweden;6. State Key Laboratory of Membrane Biology, Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China;7. Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, China;8. Division of Abdominal Cancer, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, and National Collaborative Center for Biotherapy, Chengdu, China;9. Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China |
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| Abstract: | Generation of single‐stranded DNA (ssDNA) is required for the template strand formation during DNA replication. Replication Protein A (RPA) is an ssDNA‐binding protein essential for protecting ssDNA at replication forks in eukaryotic cells. While significant progress has been made in characterizing the role of the RPA–ssDNA complex, how RPA is loaded at replication forks remains poorly explored. Here, we show that the Saccharomyces cerevisiae protein regulator of Ty1 transposition 105 (Rtt105) binds RPA and helps load it at replication forks. Cells lacking Rtt105 exhibit a dramatic reduction in RPA loading at replication forks, compromised DNA synthesis under replication stress, and increased genome instability. Mechanistically, we show that Rtt105 mediates the RPA–importin interaction and also promotes RPA binding to ssDNA directly in vitro, but is not present in the final RPA–ssDNA complex. Single‐molecule studies reveal that Rtt105 affects the binding mode of RPA to ssDNA. These results support a model in which Rtt105 functions as an RPA chaperone that escorts RPA to the nucleus and facilitates its loading onto ssDNA at replication forks. |
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| Keywords: | replication fork replication stress RPA chaperone Rtt105 |
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