1. Structural Biology and Molecular Biophysics
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Human RPA activates BLM's bidirectional DNA unwinding from a nick

  1. Zhenheng Qin
  2. Lulu Bi
  3. Xi-Miao Hou
  4. Siqi Zhang
  5. Xia Zhang
  6. Ying Lu
  7. Ming Li
  8. Mauro Modesti
  9. Xu-Guang Xi  Is a corresponding author
  10. Bo Sun  Is a corresponding author
  1. ShanghaiTech University, China
  2. Northwest A&F University, China
  3. Chinese Academy of Sciences, China
  4. Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, France
  5. Ecole Normale Supérieure de Cachan, France
Research Article
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Cite this article as: eLife 2020;9:e54098 doi: 10.7554/eLife.54098

Abstract

BLM is a multifunctional helicase that plays critical roles in maintaining genome stability. It processes distinct DNA substrates, but not nicked DNA, during many steps in DNA replication and repair. However, how BLM prepares itself for diverse functions remains elusive. Here, using a combined single-molecule approach, we find that a high abundance of BLMs can indeed unidirectionally unwind dsDNA from a nick when an external destabilizing force is applied. Strikingly, human replication protein A (hRPA) not only ensures that limited quantities of BLMs processively unwind nicked dsDNA under a reduced force but also permits the translocation of BLMs on both intact and nicked ssDNAs, resulting in a bidirectional unwinding mode. This activation necessitates BLM targeting on the nick and the presence of free hRPAs in solution whereas direct interactions between them are dispensable. Our findings present novel DNA unwinding activities of BLM that potentially facilitate its function switching in DNA repair.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1, 3, 4 and 5.

Article and author information

Author details

  1. Zhenheng Qin

    School of Life Science and Technology, ShanghaiTech University, Shanghai, China
    Competing interests
    The authors declare that no competing interests exist.
  2. Lulu Bi

    School of Life Science and Tehnology, ShanghaiTech University, Shanghai, China
    Competing interests
    The authors declare that no competing interests exist.
  3. Xi-Miao Hou

    College of Life Sciences, Northwest A&F University, Yangling, China
    Competing interests
    The authors declare that no competing interests exist.
  4. Siqi Zhang

    School of Life Science and Tehnology, ShanghaiTech University, Shanghai, China
    Competing interests
    The authors declare that no competing interests exist.
  5. Xia Zhang

    School of Life Science and Tehnology, ShanghaiTech University, Shanghai, China
    Competing interests
    The authors declare that no competing interests exist.
  6. Ying Lu

    Institute of Physics, Chinese Academy of Sciences, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  7. Ming Li

    Institute of Physics, Chinese Academy of Sciences, Beijing, China
    Competing interests
    The authors declare that no competing interests exist.
  8. Mauro Modesti

    Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Marseille, France
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4964-331X
  9. Xu-Guang Xi

    Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, Cachan, France
    For correspondence
    xxi01@ens-cachan.fr
    Competing interests
    The authors declare that no competing interests exist.
  10. Bo Sun

    School of Life Science and Tehnology, ShanghaiTech University, Shanghai, China
    For correspondence
    sunbo@shanghaitech.edu.cn
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4590-7795

Funding

Ministry of Science and Technology of the People's Republic of China (2016YFA0500902)

  • Bo Sun

Ministry of Science and Technology of the People's Republic of China (2017YFA0106700)

  • Bo Sun

The Natural Science Foundation of Shanghai (19ZR1434100)

  • Bo Sun

The French National Cancer Institute (PLBIO2017-167)

  • Mauro Modesti

The French National League Against Cancer (EL2028.LNCC/MaM)

  • Mauro Modesti

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Maria Spies, University of Iowa, United States

Publication history

  1. Received: December 2, 2019
  2. Accepted: February 25, 2020
  3. Accepted Manuscript published: February 26, 2020 (version 1)
  4. Version of Record published: March 11, 2020 (version 2)

Copyright

© 2020, Qin et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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