1. Structural Biology and Molecular Biophysics
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Nucleophosmin integrates within the nucleolus via multi-modal interactions with proteins displaying R-rich linear motifs and rRNA

  1. Diana M Mitrea
  2. Jaclyn A Cika
  3. Clifford S Guy
  4. David Ban
  5. Priya R Banerjee
  6. Christopher B Stanley
  7. Amanda Nourse
  8. Ashok A Deniz
  9. Richard W Kriwacki  Is a corresponding author
  1. St. Jude Children's Research Hospital, United States
  2. University of Louisville, United States
  3. The Scripps Research Institute, United States
  4. Oak Ridge National Laboratory, United States
Research Article
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Cite this article as: eLife 2016;5:e13571 doi: 10.7554/eLife.13571

Abstract

The nucleolus is a membrane-less organelle formed through liquid-liquid phase separation of its components from the surrounding nucleoplasm. Here, we show that nucleophosmin (NPM1) integrates within the nucleolus via a multi-modal mechanism involving multivalent interactions with proteins containing arginine-rich linear motifs (R-motifs) and rRNA. Importantly, these R-motifs are found in canonical nucleolar localization signals. Based on a novel combination of approaches, including smFRET, NMR, and SANS, we propose a model for the molecular organization within liquid-like droplets formed by the N-terminal domain of NPM1 and R-motif peptides, thus providing insights into the structural organization of the nucleolus. We identify multivalency of acidic tracts and folded nucleic acid binding domains, mediated by N-terminal domain oligomerization, as structural features required for phase separation of NPM1 with other nucleolar components in vitro and for localization within mammalian nucleoli. We propose that one mechanism of nucleolar localization involves phase separation of proteins within the nucleolus.

Article and author information

Author details

  1. Diana M Mitrea

    Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Jaclyn A Cika

    Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Clifford S Guy

    Department of Immunology, St. Jude Children's Research Hospital, Memphis, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. David Ban

    Cancer Center, University of Louisville, Louisville, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Priya R Banerjee

    Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Christopher B Stanley

    Biology and Biomedical Sciences Group, Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Amanda Nourse

    Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Ashok A Deniz

    Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
    Competing interests
    The authors declare that no competing interests exist.
  9. Richard W Kriwacki

    Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
    For correspondence
    richard.kriwacki@stjude.org
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Michael K Rosen, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, United States

Publication history

  1. Received: December 6, 2015
  2. Accepted: January 21, 2016
  3. Accepted Manuscript published: February 2, 2016 (version 1)
  4. Accepted Manuscript updated: February 4, 2016 (version 2)
  5. Version of Record published: February 29, 2016 (version 3)

Copyright

© 2016, Mitrea 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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