1. Biochemistry and Chemical Biology
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An explanation for origin unwinding in eukaryotes

  1. Lance D Langston
  2. Michael E O'Donnell  Is a corresponding author
  1. The Rockefeller University, United States
  2. Howard Hughes Medical Institute, The Rockefeller University, United States
Research Article
  • Cited 8
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Cite this article as: eLife 2019;8:e46515 doi: 10.7554/eLife.46515


Twin CMG complexes are assembled head-to-head around duplex DNA at eukaryotic origins of replication. Mcm10 activates CMGs to form helicases that encircle single-strand (ss) DNA and initiate bidirectional forks. How the CMGs melt duplex DNA while encircling it is unknown. Here we show that S. cerevisiae CMG tracks with force while encircling double-stranded (ds) DNA and that in the presence of Mcm10 the CMG melts long blocks of dsDNA while it encircles dsDNA. We demonstrate that CMG tracks mainly on the 3'-5' strand during duplex translocation, predicting that head-to-head CMGs at an origin exert force on opposite strands. Accordingly, we show that CMGs that encircle double strand DNA in a head-to-head orientation melt the duplex in an Mcm10-dependent reaction.

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All data generated or analysed during this study are included in the manuscript and supporting files.

Article and author information

Author details

  1. Lance D Langston

    The Rockefeller University, New York City, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2736-9284
  2. Michael E O'Donnell

    Laboratory of DNA Replication, Howard Hughes Medical Institute, The Rockefeller University, New York City, United States
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9002-4214


Howard Hughes Medical Institute

  • Michael E O'Donnell

National Institutes of Health (GM115809)

  • Michael E O'Donnell

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

Reviewing Editor

  1. James M Berger, Johns Hopkins University School of Medicine, United States

Publication history

  1. Received: March 1, 2019
  2. Accepted: July 6, 2019
  3. Accepted Manuscript published: July 8, 2019 (version 1)
  4. Version of Record published: July 16, 2019 (version 2)


© 2019, Langston & O'Donnell

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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